The Journal of Bone and Joint Surgery-American Volume, 2002
Acetabular osteolysis is a major problem affecting long-term survival of total hip prostheses. Si... more Acetabular osteolysis is a major problem affecting long-term survival of total hip prostheses. Since lytic lesions may be asymptomatic until extensive bone loss has occurred, early detection of lytic lesions is important. The purposes of this study were to determine the efficacy and potential role of high-resolution helical (or spiral) computed tomography with metal-artifact minimization in the early detection of osteolysis of the pelvis and to use the method to determine if there was a relationship between the extent of osteolysis and the amount of polyethylene wear. Forty patients (fifty hips) who had undergone primary cementless total hip arthroplasty between 1988 and 1994 were evaluated as part of an ongoing prospective study. These patients had a history of high-level activity that was believed to place them at increased risk for accelerated polyethylene wear. The most recent follow-up radiographs were compared with the three-month postoperative radiographs. Helical computed tomography scans with metal-artifact minimization were made, and evidence of osteolytic lesions on these scans was compared with that on the radiographs. Two-dimensional wear analysis was performed with use of digitized radiographs, and the results were compared with loss of bone volume as calculated from the computed tomography scans. Acetabular lysis was identified on the radiographs of sixteen hips and on the computed tomography scans of twenty-six hips. Radiographs underestimated the extent of the lysis in thirteen of the sixteen hips. There was no correlation (r = 0.036) between linear wear and the measured volume of bone loss, with the numbers available. On the basis of the amount of lysis seen on the computed tomography scans, one patient underwent a revision procedure. Helical computed tomography with metal-artifact minimization is more sensitive for identifying and quantifying osteolysis after total hip arthroplasty than is plain radiography. Since computed tomography scans show both the extent and the location of lytic lesions, they are useful to guide treatment decisions as well as to assist in planning for surgical intervention, when needed, in patients with suspected osteolysis.
When compared with traditional techniques, computer-assisted total knee arthroplasty (TKA) has be... more When compared with traditional techniques, computer-assisted total knee arthroplasty (TKA) has been shown to allow more accurate coronal alignment of the implants with fewer “outliers.” Most navigation systems in computer-assisted TKA utilize rigidly-fixed trackers placed on both the femur and tibia, a computer workstation, and navigation software to determine the mechanical axis of the extremity intraoperatively, in real time. The purpose of this study was to report the initial experience of a single surgeon with a novel navigation system. This system utilizes a “pinless” technique using trackers that are mounted at the articular surface of the knee instead of being fixed to the femur and tibia. Sixty-Six consecutive TKAs were performed using a novel “pinless” navigation system by a single surgeon. At 4 weeks post-operatively, coronal alignment was assessed with long-standing AP radiographs. The alignment measurements were then compared to historical controls. The average alignment in the coronal plane was 1.73° +/−1.50° deviation from neutral alignment. Variance was 2.26°. The c onfidence interval constructed with an alpha value of.05 was (1.50°, 2.40°). Five knees had a coronal alignment greater than 3° from neutral. Of these five, three had an ipsilateral total hip replacement, and 2 were morbidly obese. There were no pin site infections nor pin site fractures. There was 1 late hematogenous infection. This study reports an initial single-surgeon experience of a novel “pinless” navigation technique for TKA. The technique in this study is a novel and safe method to reconstruct a neutral mechanical axis, as it avoids the morbidity of the application of navigation tracking pins and therefore enhances patient safety.
Computer-assisted total knee arthroplasty has been demonstrated to provide reproducible limb mech... more Computer-assisted total knee arthroplasty has been demonstrated to provide reproducible limb mechanical alignment within 3°from the neutral mechanical axis. However, restoring proper implant and extremity alignment remains a significant challenge with proximal tibial deficiencies. In this prospective study, we describe the use of computer navigation to quantify the amount of bone loss on the medial or lateral tibial plateau and the use of these data to assess the need for augmentation with metallic tibial wedges. In this study, we demonstrate that computer-assisted total knee arthroplasty in patients with significant tibial deformities can accurately measure severe tibial deformities, predict tibial augment thickness, and provide excellent mechanical alignment and restore the joint line without excessive bony resection, repeated osteotomies, and repeated augment trialing.
Patients with a thrombotic history are thought to be at greater risk for developing blood clots f... more Patients with a thrombotic history are thought to be at greater risk for developing blood clots following total hip arthroplasty (THA) or total knee arthroplasty (TKA). The incidence of venous thromboembolism and risk factors associated with clot development in this population of patients, however, are not well defined. From the years 2002 to 2008, 547 patients undergoing elective joint arthroplasty with a history of thrombotic disease, defined by prior history of deep venous thrombosis (DVT) or pulmonary embolism (PE), were followed prospectively for a minimum of one month after TKA or THA. Patients received prophylactic anticoagulation with coumadin starting on POD 1 with or without bridge therapy with low molecular weight heparin (LMWH). Patients were compared for the following risk factors: advanced age (>70 years old), inherited or acquired thrombophilia, time elapsed since prior episode, association of prior episode with surgery, and method of anticoagulation. Of the 547 pa...
Background/Introduction As a new generation of robotic systems is introduced into the world of ar... more Background/Introduction As a new generation of robotic systems is introduced into the world of arthroplasty, Robotic-Assisted Total Knee Arthroplasty (TKA) represents a growing proportion of a reco...
Computer Assisted Total Knee Arthroplasty (CAS TKR) has been shown to provide excellent and repro... more Computer Assisted Total Knee Arthroplasty (CAS TKR) has been shown to provide excellent and reproducible limb mechanical alignment. CAS TKR has also been demonstrated to reduce limb alignment variance and outliers. Previous studies have shown improved mechanical alignment both radiographically and clinically. Specifically, CAS TKR has been shown to result in alignment deviations less than 3 degrees from neutral mechanical femoral and tibial axes. Furthermore, CAS TKR also permits any significant pre-operative tibial deformity to be quantified prior to performing tibial osteotomies. In this study, we describe the use of computer navigation to quantify the amount of bone loss on the medial or lateral tibial plateau and the subsequent use of this data to assess the need for augmentation with tibial wedges. Two hundred and thirty consecutive primary computer assisted total knee arthroplasties were performed by one senior surgeon (L.P.) at Northwestern Memorial Hospital. In all cases, the tibial deformity was quantified and recorded intraoperatively using computer navigation software. The deformity was recorded in the navigation software by inputting the lowest point on the deformed tibial plateau and the mid point on the non-deformed tibial plateau using navigation markers. After Institutional Review Board approval was obtained, a retrospective review of the patient operative reports and patient charts was performed. Operative reports were reviewed to identify cases with the difference between the values of medial and lateral tibial plateaus exceeded thirteen millimeters and cases when tibial augmentation was performed. In cases utilising medial or lateral tibial augmentation, pre operative and post operative anterior posterior and lateral knee radiographs and long leg standing anterior posterior radiographs were reviewed to measure the joint line restoration and final mechanical limb alignment. All two hundred and thirty operative dictations and patient charts were reviewed. In seven cases, the difference between the values of the medial and lateral tibial plateaus was greater than thirteen millimeters. In all seven cases, tibial augmentation was utilized in order to prevent resection of tibial bone in excess of fourteen millimeters. In cases with a difference of medial and lateral tibial plateau values of less than thirteen millimeters, no tibial augmentation was utilised. For the seven cases using tibial augmentation, preoperative and post-operative knee and long standing radiographs were reviewed to examine joint line restoration and final limb alignment. In all seven patients, joint line restoration was successful within 4 millimeters and long standing radiographs revealed excellent limb alignment. Computer Assisted Total Knee Arthroplasty has already been shown to provide excellent limb alignment and reduce variance and outliers. We demonstrate that Computer Assisted Total Knee Arthroplasty in patients with significant tibial deformities can help assess and the amount of bone loss on the medial or lateral tibial plateaus. Excessive tibial resection to restore the mechanical axis and joint line can be avoided by quantifying the amount of tibial bone loss prior to osteotomy. Thus, Computer Assisted Total Knee Arthroplasty can successfully restore the joint line and overall limb alignment with conservative bone resection in patients with significant pre-operative tibial deformities.
European Journal of Orthopaedic Surgery & Traumatology
Background Despite continued advances in techniques and implant designs, a population of patients... more Background Despite continued advances in techniques and implant designs, a population of patients who are dissatisfied after total knee arthroplasty (TKA) remains. During robotic-assisted arthroplasty, real-time intraoperative assessment of patient knee alignment is performed. Here, we assess the prevalence of an under-appreciated deformity, reverse coronal deformity (RCD), and the benefits of utilizing robotic-assisted knee arthroplasty to help correct this dynamic deformity. Methods A retrospective study evaluating patients undergoing robotic-assisted cruciate-retaining TKA was performed. Intraoperative measurements were obtained using tibial and femoral arrays to assess coronal plane deformity at full extension and at 90° flexion. RCD was defined as ≥ 2° varus in knee extension that reversed to ≥ 2° valgus in flexion, or vice-versa. Coronal plane deformity was then reassessed after robotic-assisted bony resection and implant placement. Results Of 204 patients that underwent TKA, 16 patients (7.8%) were found to have RCD, with 14 patients (87.5%) transitioning from varus in extension to valgus in flexion. The average coronal deformity was 7.75°, with a maximum of 12°. These improved to an average coronal change of 0.93° post-TKA. Final medial and lateral gaps were all balanced to within 1° in extension and flexion. Another 34 patients (16.7%) had ≥ 5° change in coronal plane deformity from extension to flexion (average 6.39°), however, did not experience a reversal of their coronal deformity. Outcomes were assessed with KOOS Jr. scores postoperatively. Conclusion Computer and robotic assistance were utilized to demonstrate the prevalence of RCD. We also demonstrated accurate identification and successfully balancing of RCD utilizing robotic-assisted TKA. An increased awareness of these dynamic deformities could aid surgeons in proper gap balancing even in the absence of navigation and robotic-assisted surgery.
Polyethylene wear and subsequent osteolysis are major obstacles to the long-term success of total... more Polyethylene wear and subsequent osteolysis are major obstacles to the long-term success of total hip arthroplasty (THA). We conducted a study to determine the incidence of loose acetabular components that did not show frank signs of loosening on either plain radiography or computed tomography (CT), or radiographically silent loosening (RSL). In this retrospective study, we evaluated patients who underwent revision THA and were evaluated with plain radiography and CT between 2000 and 2012. Any patient with imaging that showed signs of component movement was excluded. Of the 104 patients who met the study inclusion criteria, 17 (16.3%) met the criteria for RSL of the acetabular shell. Patients with RSL presented at a similar age (P = .961) and with a similar sex profile (P = .185) compared with patients with stable acetabular components and were more likely to present with pain (P = .0487). Acetabular components may be loose even if there is no evidence of component migration on radiographic studies. Surgeons should be aware of the incidence of RSL and the potential of RSL to affect patient care and potential surgical options.
The current decade has seen a marked rise in popularity of minimally invasive hip replacement, do... more The current decade has seen a marked rise in popularity of minimally invasive hip replacement, done through a variety of surgical approaches. A specific downside to the direct anterior approach includes the significant difficulty getting a “straight shot” down the femoral canal for either straight, nonflexible reaming or broaching as with standard approaches. Improper alignment in the femoral canal can lead to sub-optimal load transfer and thus compromised fixation. The femoral broach and stem insertion path for this approach is best described as a curved one, rather than the typical straight path. Some femoral components appear to be more suitable to this technique due to their geometries. The purpose of the study was to describe the effects that the single geometric parameter, stem length, has on its insertion path into the femoral canal. Due to the potential introduction of human error associated with repetitively performing a specific motion, both a physical study and a computer...
Introduction The published results of the use of a dual mobility cup to prevent instability in pr... more Introduction The published results of the use of a dual mobility cup to prevent instability in primary and revision total hip arthroplasty (THA) have established its efficacy. However, the monoblock, porous cobalt chromium cup design makes secure fixation difficult to achieve, limiting its use in patients with significant acetabular deformity or bone loss. Recently, a modular version of the dual mobility cup was introduced, consisting of a conventional porous shell with holes to allow augmented screw fixation, a highly polished modular metal liner, and a standard bipolar femoral head. The purpose of this report is to present its various indications, the surgical technique, and report our initial results. Methods With IRB approval and FDA clearance, we implanted the modular dual mobility (MDM) cup in 15 patients undergoing primary and 5 patients undergoing revision THA deemed high risk for instability. Indications included septic and aseptic revision surgery, developmental hip dyspla...
Introduction Joint reconstruction remains a successful and popular surgery with advances in appro... more Introduction Joint reconstruction remains a successful and popular surgery with advances in approaches, implants and techniques continually forthcoming. Various methods of skin closure exist to address issues in efficiency, aesthetics, and barrier to infection. While subcuticular skin closure techniques offer an aesthetic advantage to conventional skin stapling, no measurable differences have been reported. Furthermore, newer barbed sutures, such as the V-loc absorbable suture, theoretically distribute tension evenly through the wound and help decrease knot-related complications. To our knowledge, no literature exists on the rate of wound complications in joint arthroplasty with the use of V-loc suture for skin closure. We hypothesize that despite theoretical gains, skin closure with a V-loc (Covidien, Mansfield, MA) absorbable suture should be performed with caution. Methods & Materials A retrospective chart review was conducted of 278 consecutive primary joint reconstruction cases...
Background This study sought to evaluate the patient experience and short-term clinical outcomes ... more Background This study sought to evaluate the patient experience and short-term clinical outcomes associated with the hospital stay of patients who underwent robotic arm-assisted total knee arthroplasty (TKA). These results were compared with a cohort of patients who underwent TKA without robotic assistance performed by the same surgeon prior to the introduction of this technology. Materials and Methods A cohort of consecutive patients undergoing primary TKA for the diagnosis of osteoarthritis by a single fellowship trained orthopaedic surgeon over a 39-month period was identified. Patients who underwent TKA during the year that this surgeon transitioned his entire knee arthroplasty practice to robotic assistance were excluded to eliminate selection bias and control for the learning curve. All patients received the same prosthesis and postoperative pain protocol. Patients that required intubation for failed spinal anesthetic were excluded. A final population of 492 TKAs was identifie...
BACKGROUND While there are many possible complications associated with total joint arthroplasty (... more BACKGROUND While there are many possible complications associated with total joint arthroplasty (TJA), venous thromboembolism (VTE) is both frequent and potentially severe. Despite this importance, there are inconsistent recommendations for prophylaxis based on patient risk factors. METHODS A predictive model was constructed to compare low-molecular-weight heparin(LMWH) and aspirin (ASA) for prevention of VTE-associated complications following TJA.The model used risks from prior prophylaxis studies to estimate the risk of developing a symptomatic deep vein thrombosis, pulmonary embolism, thrombocytopenia, and operative or nonoperative site bleeding. We also evaluated the progression to 4 possible final health states: postphlebitis syndrome, intracranial hemorrhage, death, or baseline health. Within published ranges, we selected assumptions that were favorable to LMWH such that these analyses represent a best case scenario for LMWH or an alternative more aggressive low-molecular-weight heparin alternative (LMWHA). Events and outcomes were assigned quality-adjusted life-year (QALY) losses according to prior studies to determine the effect on patients' outcomes for ASA and LMWHA prophylaxis. RESULTS Assessing VTE risk populations from 0.2% to 2% with life expectancies ranging from 5 to 40 years postoperatively, patients with a risk ratio less than 3.7 showed increased expected QALY with ASA compared to LMWHA. For patients with a baseline VTE risk of 1% and a 15 year life expectancy, a risk ratio of 13.4 was needed to identify patients that would benefit from LMWHA. With life expectancy increased to 30 years, the risk ratio needed to idetify these patients was 7.4. CONCLUSION Patients undergoing TJA should receive ASA chemoprophylaxis in nearly all situations, unless the patient has a significantly increased VTE risk compared to the baseline population and a long life expectancy.
The purpose of this prospective controlled trial was to determine whether decrease in contaminati... more The purpose of this prospective controlled trial was to determine whether decrease in contamination could be achieved in nonnavigated and navigated total knee arthroplasties by replacing traditional saws, cutting blocks, and trials with specialized saws and single-use cutting blocks and trials. Various tray wrapping metrics during total knee arthroplasty were measured in 400 procedures performed by 8 different surgeons at 6 institutions. Instrumentation contamination was determined by counting the number of tray sterility indicators, pans, and instruments that were compromised. The results show that a decrease in contamination was evident in 57% (nonnavigated) and 32% (navigated) fewer compromises of tray sterility indicators, pans, and instruments. Single-use instruments show promising benefits, but further study is needed to confirm safety and efficacy before they can be widely adopted. The authors believe that the use of single-use instruments, cutting guides, and trial implants for total knee arthroplasty will play an increasing role in decreasing operating room contamination and potential deep infections.
In the past, treatment of knee osteoarthritis has been limited to unicompartmental knee replaceme... more In the past, treatment of knee osteoarthritis has been limited to unicompartmental knee replacement or total knee arthroplasty (TKA). Neither option is well suited for the active patient with midstage osteoarthritis of the medial and patellofemoral compartments. Now an alternative treatment is available that targets the diseased area without sacrifice of normal bone or both the cruciate ligaments. Minimally invasive surgical techniques are easily used, which reduces tissue trauma and results in a quicker recovery than TKA. Bicompartmental replacement offers decreased pain, stability through normal ligament structure, and the retention of normal bone for patients with medial and patellofemoral osteoarthritis.
The purpose of this study was to evaluate the impact of a preoperative myocardial infarction (MI)... more The purpose of this study was to evaluate the impact of a preoperative myocardial infarction (MI) on outcomes of inpatient orthopaedic operations. The National Surgical Quality Improvement Program database was used to identify patients who underwent common orthopaedic operations from 2006 to 2010. Patient demographic data, comorbidities, complications, and lengths of stay were collected. Multivariate logistic regression and linear regression models were used to compare outcomes for patients with and without a history of MI in the six months prior to surgery. Of the 32,462 patients identified, 86 had sustained an MI in the six months prior to surgery. The MI cohort had no cardiac complications but had increased incidences of superficial surgical site infection, unplanned re-intubation, ventilator-assisted respiration for more than 48 hours, pneumonia, sepsis or septic shock, and postoperative mortality within 30 days of surgery, as well as prolonged lengths of stay. Following logistic regression to adjust for baseline differences, a history of MI showed no association with cardiac complications and was significantly associated with superficial surgical site infection (OR 3.6, 95% CI 1.1-11.8), ventilator dependence for over 48 hours (OR 4.0, 95% CI 1.1-14.0), and extended length of stay (median with interquartile range 4 [4-4] vs. 5 [5-5] days). A myocardial infarction within six months prior to orthopaedic surgery is not associated with a higher risk of 30-day perioperative cardiac complications; however, it is associated with increased rates of surgical site infection, prolonged ventilator dependence, and longer hospital stay.
Treatment methods for osteonecrosis (avascular necrosis) are wide and varied. When untreated, pro... more Treatment methods for osteonecrosis (avascular necrosis) are wide and varied. When untreated, progression of the disease is common and may dictate femoral head replacement. However, before femoral head collapse, some patients have mechanical joint symptoms (locking, buckling, clicking) that are unaddressed by femoral head drilling alone. Radiographic examinations in these patients usually are nondiagnostic. Patients with these clinical criteria were evaluated arthroscopically. Between 1993 and 2000, seven patients were identified with known documented or radiographic diagnosis of avascular necrosis who had hip arthroscopy. Each patient's preoperative history, physical examination, plain radiographs, magnetic resonance imaging scans, and operative notes were reviewed from a prospectively-derived database. The duration and onset of symptoms were identified carefully. Case histories are presented on five of these patients. Articular cartilage changes were recorded and correlated to the preoperative radiologic studies. Hip arthroscopy is a minimally invasive, highly effective, joint-preserving surgery in the young patient with mechanical symptoms (locking, catching, buckling) and early avascular necrosis. Treatable lesions include loose bodies, synovitis, chondral flaps, and labral tears. In addition, accurate staging can be accomplished through direct observation.
The Journal of Bone and Joint Surgery-American Volume, 2002
Acetabular osteolysis is a major problem affecting long-term survival of total hip prostheses. Si... more Acetabular osteolysis is a major problem affecting long-term survival of total hip prostheses. Since lytic lesions may be asymptomatic until extensive bone loss has occurred, early detection of lytic lesions is important. The purposes of this study were to determine the efficacy and potential role of high-resolution helical (or spiral) computed tomography with metal-artifact minimization in the early detection of osteolysis of the pelvis and to use the method to determine if there was a relationship between the extent of osteolysis and the amount of polyethylene wear. Forty patients (fifty hips) who had undergone primary cementless total hip arthroplasty between 1988 and 1994 were evaluated as part of an ongoing prospective study. These patients had a history of high-level activity that was believed to place them at increased risk for accelerated polyethylene wear. The most recent follow-up radiographs were compared with the three-month postoperative radiographs. Helical computed tomography scans with metal-artifact minimization were made, and evidence of osteolytic lesions on these scans was compared with that on the radiographs. Two-dimensional wear analysis was performed with use of digitized radiographs, and the results were compared with loss of bone volume as calculated from the computed tomography scans. Acetabular lysis was identified on the radiographs of sixteen hips and on the computed tomography scans of twenty-six hips. Radiographs underestimated the extent of the lysis in thirteen of the sixteen hips. There was no correlation (r = 0.036) between linear wear and the measured volume of bone loss, with the numbers available. On the basis of the amount of lysis seen on the computed tomography scans, one patient underwent a revision procedure. Helical computed tomography with metal-artifact minimization is more sensitive for identifying and quantifying osteolysis after total hip arthroplasty than is plain radiography. Since computed tomography scans show both the extent and the location of lytic lesions, they are useful to guide treatment decisions as well as to assist in planning for surgical intervention, when needed, in patients with suspected osteolysis.
When compared with traditional techniques, computer-assisted total knee arthroplasty (TKA) has be... more When compared with traditional techniques, computer-assisted total knee arthroplasty (TKA) has been shown to allow more accurate coronal alignment of the implants with fewer “outliers.” Most navigation systems in computer-assisted TKA utilize rigidly-fixed trackers placed on both the femur and tibia, a computer workstation, and navigation software to determine the mechanical axis of the extremity intraoperatively, in real time. The purpose of this study was to report the initial experience of a single surgeon with a novel navigation system. This system utilizes a “pinless” technique using trackers that are mounted at the articular surface of the knee instead of being fixed to the femur and tibia. Sixty-Six consecutive TKAs were performed using a novel “pinless” navigation system by a single surgeon. At 4 weeks post-operatively, coronal alignment was assessed with long-standing AP radiographs. The alignment measurements were then compared to historical controls. The average alignment in the coronal plane was 1.73° +/−1.50° deviation from neutral alignment. Variance was 2.26°. The c onfidence interval constructed with an alpha value of.05 was (1.50°, 2.40°). Five knees had a coronal alignment greater than 3° from neutral. Of these five, three had an ipsilateral total hip replacement, and 2 were morbidly obese. There were no pin site infections nor pin site fractures. There was 1 late hematogenous infection. This study reports an initial single-surgeon experience of a novel “pinless” navigation technique for TKA. The technique in this study is a novel and safe method to reconstruct a neutral mechanical axis, as it avoids the morbidity of the application of navigation tracking pins and therefore enhances patient safety.
Computer-assisted total knee arthroplasty has been demonstrated to provide reproducible limb mech... more Computer-assisted total knee arthroplasty has been demonstrated to provide reproducible limb mechanical alignment within 3°from the neutral mechanical axis. However, restoring proper implant and extremity alignment remains a significant challenge with proximal tibial deficiencies. In this prospective study, we describe the use of computer navigation to quantify the amount of bone loss on the medial or lateral tibial plateau and the use of these data to assess the need for augmentation with metallic tibial wedges. In this study, we demonstrate that computer-assisted total knee arthroplasty in patients with significant tibial deformities can accurately measure severe tibial deformities, predict tibial augment thickness, and provide excellent mechanical alignment and restore the joint line without excessive bony resection, repeated osteotomies, and repeated augment trialing.
Patients with a thrombotic history are thought to be at greater risk for developing blood clots f... more Patients with a thrombotic history are thought to be at greater risk for developing blood clots following total hip arthroplasty (THA) or total knee arthroplasty (TKA). The incidence of venous thromboembolism and risk factors associated with clot development in this population of patients, however, are not well defined. From the years 2002 to 2008, 547 patients undergoing elective joint arthroplasty with a history of thrombotic disease, defined by prior history of deep venous thrombosis (DVT) or pulmonary embolism (PE), were followed prospectively for a minimum of one month after TKA or THA. Patients received prophylactic anticoagulation with coumadin starting on POD 1 with or without bridge therapy with low molecular weight heparin (LMWH). Patients were compared for the following risk factors: advanced age (>70 years old), inherited or acquired thrombophilia, time elapsed since prior episode, association of prior episode with surgery, and method of anticoagulation. Of the 547 pa...
Background/Introduction As a new generation of robotic systems is introduced into the world of ar... more Background/Introduction As a new generation of robotic systems is introduced into the world of arthroplasty, Robotic-Assisted Total Knee Arthroplasty (TKA) represents a growing proportion of a reco...
Computer Assisted Total Knee Arthroplasty (CAS TKR) has been shown to provide excellent and repro... more Computer Assisted Total Knee Arthroplasty (CAS TKR) has been shown to provide excellent and reproducible limb mechanical alignment. CAS TKR has also been demonstrated to reduce limb alignment variance and outliers. Previous studies have shown improved mechanical alignment both radiographically and clinically. Specifically, CAS TKR has been shown to result in alignment deviations less than 3 degrees from neutral mechanical femoral and tibial axes. Furthermore, CAS TKR also permits any significant pre-operative tibial deformity to be quantified prior to performing tibial osteotomies. In this study, we describe the use of computer navigation to quantify the amount of bone loss on the medial or lateral tibial plateau and the subsequent use of this data to assess the need for augmentation with tibial wedges. Two hundred and thirty consecutive primary computer assisted total knee arthroplasties were performed by one senior surgeon (L.P.) at Northwestern Memorial Hospital. In all cases, the tibial deformity was quantified and recorded intraoperatively using computer navigation software. The deformity was recorded in the navigation software by inputting the lowest point on the deformed tibial plateau and the mid point on the non-deformed tibial plateau using navigation markers. After Institutional Review Board approval was obtained, a retrospective review of the patient operative reports and patient charts was performed. Operative reports were reviewed to identify cases with the difference between the values of medial and lateral tibial plateaus exceeded thirteen millimeters and cases when tibial augmentation was performed. In cases utilising medial or lateral tibial augmentation, pre operative and post operative anterior posterior and lateral knee radiographs and long leg standing anterior posterior radiographs were reviewed to measure the joint line restoration and final mechanical limb alignment. All two hundred and thirty operative dictations and patient charts were reviewed. In seven cases, the difference between the values of the medial and lateral tibial plateaus was greater than thirteen millimeters. In all seven cases, tibial augmentation was utilized in order to prevent resection of tibial bone in excess of fourteen millimeters. In cases with a difference of medial and lateral tibial plateau values of less than thirteen millimeters, no tibial augmentation was utilised. For the seven cases using tibial augmentation, preoperative and post-operative knee and long standing radiographs were reviewed to examine joint line restoration and final limb alignment. In all seven patients, joint line restoration was successful within 4 millimeters and long standing radiographs revealed excellent limb alignment. Computer Assisted Total Knee Arthroplasty has already been shown to provide excellent limb alignment and reduce variance and outliers. We demonstrate that Computer Assisted Total Knee Arthroplasty in patients with significant tibial deformities can help assess and the amount of bone loss on the medial or lateral tibial plateaus. Excessive tibial resection to restore the mechanical axis and joint line can be avoided by quantifying the amount of tibial bone loss prior to osteotomy. Thus, Computer Assisted Total Knee Arthroplasty can successfully restore the joint line and overall limb alignment with conservative bone resection in patients with significant pre-operative tibial deformities.
European Journal of Orthopaedic Surgery & Traumatology
Background Despite continued advances in techniques and implant designs, a population of patients... more Background Despite continued advances in techniques and implant designs, a population of patients who are dissatisfied after total knee arthroplasty (TKA) remains. During robotic-assisted arthroplasty, real-time intraoperative assessment of patient knee alignment is performed. Here, we assess the prevalence of an under-appreciated deformity, reverse coronal deformity (RCD), and the benefits of utilizing robotic-assisted knee arthroplasty to help correct this dynamic deformity. Methods A retrospective study evaluating patients undergoing robotic-assisted cruciate-retaining TKA was performed. Intraoperative measurements were obtained using tibial and femoral arrays to assess coronal plane deformity at full extension and at 90° flexion. RCD was defined as ≥ 2° varus in knee extension that reversed to ≥ 2° valgus in flexion, or vice-versa. Coronal plane deformity was then reassessed after robotic-assisted bony resection and implant placement. Results Of 204 patients that underwent TKA, 16 patients (7.8%) were found to have RCD, with 14 patients (87.5%) transitioning from varus in extension to valgus in flexion. The average coronal deformity was 7.75°, with a maximum of 12°. These improved to an average coronal change of 0.93° post-TKA. Final medial and lateral gaps were all balanced to within 1° in extension and flexion. Another 34 patients (16.7%) had ≥ 5° change in coronal plane deformity from extension to flexion (average 6.39°), however, did not experience a reversal of their coronal deformity. Outcomes were assessed with KOOS Jr. scores postoperatively. Conclusion Computer and robotic assistance were utilized to demonstrate the prevalence of RCD. We also demonstrated accurate identification and successfully balancing of RCD utilizing robotic-assisted TKA. An increased awareness of these dynamic deformities could aid surgeons in proper gap balancing even in the absence of navigation and robotic-assisted surgery.
Polyethylene wear and subsequent osteolysis are major obstacles to the long-term success of total... more Polyethylene wear and subsequent osteolysis are major obstacles to the long-term success of total hip arthroplasty (THA). We conducted a study to determine the incidence of loose acetabular components that did not show frank signs of loosening on either plain radiography or computed tomography (CT), or radiographically silent loosening (RSL). In this retrospective study, we evaluated patients who underwent revision THA and were evaluated with plain radiography and CT between 2000 and 2012. Any patient with imaging that showed signs of component movement was excluded. Of the 104 patients who met the study inclusion criteria, 17 (16.3%) met the criteria for RSL of the acetabular shell. Patients with RSL presented at a similar age (P = .961) and with a similar sex profile (P = .185) compared with patients with stable acetabular components and were more likely to present with pain (P = .0487). Acetabular components may be loose even if there is no evidence of component migration on radiographic studies. Surgeons should be aware of the incidence of RSL and the potential of RSL to affect patient care and potential surgical options.
The current decade has seen a marked rise in popularity of minimally invasive hip replacement, do... more The current decade has seen a marked rise in popularity of minimally invasive hip replacement, done through a variety of surgical approaches. A specific downside to the direct anterior approach includes the significant difficulty getting a “straight shot” down the femoral canal for either straight, nonflexible reaming or broaching as with standard approaches. Improper alignment in the femoral canal can lead to sub-optimal load transfer and thus compromised fixation. The femoral broach and stem insertion path for this approach is best described as a curved one, rather than the typical straight path. Some femoral components appear to be more suitable to this technique due to their geometries. The purpose of the study was to describe the effects that the single geometric parameter, stem length, has on its insertion path into the femoral canal. Due to the potential introduction of human error associated with repetitively performing a specific motion, both a physical study and a computer...
Introduction The published results of the use of a dual mobility cup to prevent instability in pr... more Introduction The published results of the use of a dual mobility cup to prevent instability in primary and revision total hip arthroplasty (THA) have established its efficacy. However, the monoblock, porous cobalt chromium cup design makes secure fixation difficult to achieve, limiting its use in patients with significant acetabular deformity or bone loss. Recently, a modular version of the dual mobility cup was introduced, consisting of a conventional porous shell with holes to allow augmented screw fixation, a highly polished modular metal liner, and a standard bipolar femoral head. The purpose of this report is to present its various indications, the surgical technique, and report our initial results. Methods With IRB approval and FDA clearance, we implanted the modular dual mobility (MDM) cup in 15 patients undergoing primary and 5 patients undergoing revision THA deemed high risk for instability. Indications included septic and aseptic revision surgery, developmental hip dyspla...
Introduction Joint reconstruction remains a successful and popular surgery with advances in appro... more Introduction Joint reconstruction remains a successful and popular surgery with advances in approaches, implants and techniques continually forthcoming. Various methods of skin closure exist to address issues in efficiency, aesthetics, and barrier to infection. While subcuticular skin closure techniques offer an aesthetic advantage to conventional skin stapling, no measurable differences have been reported. Furthermore, newer barbed sutures, such as the V-loc absorbable suture, theoretically distribute tension evenly through the wound and help decrease knot-related complications. To our knowledge, no literature exists on the rate of wound complications in joint arthroplasty with the use of V-loc suture for skin closure. We hypothesize that despite theoretical gains, skin closure with a V-loc (Covidien, Mansfield, MA) absorbable suture should be performed with caution. Methods & Materials A retrospective chart review was conducted of 278 consecutive primary joint reconstruction cases...
Background This study sought to evaluate the patient experience and short-term clinical outcomes ... more Background This study sought to evaluate the patient experience and short-term clinical outcomes associated with the hospital stay of patients who underwent robotic arm-assisted total knee arthroplasty (TKA). These results were compared with a cohort of patients who underwent TKA without robotic assistance performed by the same surgeon prior to the introduction of this technology. Materials and Methods A cohort of consecutive patients undergoing primary TKA for the diagnosis of osteoarthritis by a single fellowship trained orthopaedic surgeon over a 39-month period was identified. Patients who underwent TKA during the year that this surgeon transitioned his entire knee arthroplasty practice to robotic assistance were excluded to eliminate selection bias and control for the learning curve. All patients received the same prosthesis and postoperative pain protocol. Patients that required intubation for failed spinal anesthetic were excluded. A final population of 492 TKAs was identifie...
BACKGROUND While there are many possible complications associated with total joint arthroplasty (... more BACKGROUND While there are many possible complications associated with total joint arthroplasty (TJA), venous thromboembolism (VTE) is both frequent and potentially severe. Despite this importance, there are inconsistent recommendations for prophylaxis based on patient risk factors. METHODS A predictive model was constructed to compare low-molecular-weight heparin(LMWH) and aspirin (ASA) for prevention of VTE-associated complications following TJA.The model used risks from prior prophylaxis studies to estimate the risk of developing a symptomatic deep vein thrombosis, pulmonary embolism, thrombocytopenia, and operative or nonoperative site bleeding. We also evaluated the progression to 4 possible final health states: postphlebitis syndrome, intracranial hemorrhage, death, or baseline health. Within published ranges, we selected assumptions that were favorable to LMWH such that these analyses represent a best case scenario for LMWH or an alternative more aggressive low-molecular-weight heparin alternative (LMWHA). Events and outcomes were assigned quality-adjusted life-year (QALY) losses according to prior studies to determine the effect on patients' outcomes for ASA and LMWHA prophylaxis. RESULTS Assessing VTE risk populations from 0.2% to 2% with life expectancies ranging from 5 to 40 years postoperatively, patients with a risk ratio less than 3.7 showed increased expected QALY with ASA compared to LMWHA. For patients with a baseline VTE risk of 1% and a 15 year life expectancy, a risk ratio of 13.4 was needed to identify patients that would benefit from LMWHA. With life expectancy increased to 30 years, the risk ratio needed to idetify these patients was 7.4. CONCLUSION Patients undergoing TJA should receive ASA chemoprophylaxis in nearly all situations, unless the patient has a significantly increased VTE risk compared to the baseline population and a long life expectancy.
The purpose of this prospective controlled trial was to determine whether decrease in contaminati... more The purpose of this prospective controlled trial was to determine whether decrease in contamination could be achieved in nonnavigated and navigated total knee arthroplasties by replacing traditional saws, cutting blocks, and trials with specialized saws and single-use cutting blocks and trials. Various tray wrapping metrics during total knee arthroplasty were measured in 400 procedures performed by 8 different surgeons at 6 institutions. Instrumentation contamination was determined by counting the number of tray sterility indicators, pans, and instruments that were compromised. The results show that a decrease in contamination was evident in 57% (nonnavigated) and 32% (navigated) fewer compromises of tray sterility indicators, pans, and instruments. Single-use instruments show promising benefits, but further study is needed to confirm safety and efficacy before they can be widely adopted. The authors believe that the use of single-use instruments, cutting guides, and trial implants for total knee arthroplasty will play an increasing role in decreasing operating room contamination and potential deep infections.
In the past, treatment of knee osteoarthritis has been limited to unicompartmental knee replaceme... more In the past, treatment of knee osteoarthritis has been limited to unicompartmental knee replacement or total knee arthroplasty (TKA). Neither option is well suited for the active patient with midstage osteoarthritis of the medial and patellofemoral compartments. Now an alternative treatment is available that targets the diseased area without sacrifice of normal bone or both the cruciate ligaments. Minimally invasive surgical techniques are easily used, which reduces tissue trauma and results in a quicker recovery than TKA. Bicompartmental replacement offers decreased pain, stability through normal ligament structure, and the retention of normal bone for patients with medial and patellofemoral osteoarthritis.
The purpose of this study was to evaluate the impact of a preoperative myocardial infarction (MI)... more The purpose of this study was to evaluate the impact of a preoperative myocardial infarction (MI) on outcomes of inpatient orthopaedic operations. The National Surgical Quality Improvement Program database was used to identify patients who underwent common orthopaedic operations from 2006 to 2010. Patient demographic data, comorbidities, complications, and lengths of stay were collected. Multivariate logistic regression and linear regression models were used to compare outcomes for patients with and without a history of MI in the six months prior to surgery. Of the 32,462 patients identified, 86 had sustained an MI in the six months prior to surgery. The MI cohort had no cardiac complications but had increased incidences of superficial surgical site infection, unplanned re-intubation, ventilator-assisted respiration for more than 48 hours, pneumonia, sepsis or septic shock, and postoperative mortality within 30 days of surgery, as well as prolonged lengths of stay. Following logistic regression to adjust for baseline differences, a history of MI showed no association with cardiac complications and was significantly associated with superficial surgical site infection (OR 3.6, 95% CI 1.1-11.8), ventilator dependence for over 48 hours (OR 4.0, 95% CI 1.1-14.0), and extended length of stay (median with interquartile range 4 [4-4] vs. 5 [5-5] days). A myocardial infarction within six months prior to orthopaedic surgery is not associated with a higher risk of 30-day perioperative cardiac complications; however, it is associated with increased rates of surgical site infection, prolonged ventilator dependence, and longer hospital stay.
Treatment methods for osteonecrosis (avascular necrosis) are wide and varied. When untreated, pro... more Treatment methods for osteonecrosis (avascular necrosis) are wide and varied. When untreated, progression of the disease is common and may dictate femoral head replacement. However, before femoral head collapse, some patients have mechanical joint symptoms (locking, buckling, clicking) that are unaddressed by femoral head drilling alone. Radiographic examinations in these patients usually are nondiagnostic. Patients with these clinical criteria were evaluated arthroscopically. Between 1993 and 2000, seven patients were identified with known documented or radiographic diagnosis of avascular necrosis who had hip arthroscopy. Each patient's preoperative history, physical examination, plain radiographs, magnetic resonance imaging scans, and operative notes were reviewed from a prospectively-derived database. The duration and onset of symptoms were identified carefully. Case histories are presented on five of these patients. Articular cartilage changes were recorded and correlated to the preoperative radiologic studies. Hip arthroscopy is a minimally invasive, highly effective, joint-preserving surgery in the young patient with mechanical symptoms (locking, catching, buckling) and early avascular necrosis. Treatable lesions include loose bodies, synovitis, chondral flaps, and labral tears. In addition, accurate staging can be accomplished through direct observation.
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