Daniel L. Levy

Medial Tibial Stress Shielding: A Limitation of Cobalt Chromium Tibial Baseplates.

BACKGROUND Stress shielding is a well-recognized complication associated with total knee arthroplasty. However, this phenomenon has not been thoroughly described. Specifically, no study to our knowledge has evaluated the radiographic impact of utilizing various tibial component compositions on tibial stress shielding. METHODS We retrospectively reviewed 3 cohorts of 50 patients that had a preoperative varus deformity and were implanted with a titanium, cobalt chromium (CoCr), or an all polyethylene tibial implant. A radiographic comparative analysis was performed to evaluate the amount of medial tibial bone loss in each cohort. In addition, a clinical outcomes analysis was performed on the 3 cohorts. RESULTS The CoCr was noted to have a statistically significant increase in medial tibial bone loss compared with the other 2 cohorts. The all polyethylene cohort had a statistically significantly higher final Knee Society Score and was associated with the least amount of stress shielding. CONCLUSION The CoCr tray is the most rigid of 3 implants that were compared in this study. Interestingly, this cohort had the highest amount of medial tibial bone loss. In addition, 1 patient in the CoCr cohort had medial soft tissue irritation which was attributed to a prominent medial tibial tray which required revision surgery to mitigate the symptoms.

Femoral Implant Design Modification Decreases the Incidence of Patellar Crepitus in Total Knee Arthroplasty

BACKGROUND Patellar crepitus is a complication most commonly seen in patients implanted with a posterior-stabilized total knee arthroplasty (TKA). Recently, design changes in the patellofemoral geometry and the intercondylar box ratio have been optimized in newer TKA designs. A comparative study was performed to analyze the incidence of patellar crepitus between a historical vs modern TKA design. METHODS A retrospective review of all patients at our institution that underwent a primary TKA with either a PFC Sigma or Attune posterior-stabilized TKA (DePuy, Inc, Warsaw, IN), with a minimum of 1-year follow-up duration was performed. A total of 1165 participants implanted with the PFC Sigma and 728 with the Attune design were analyzed. Patellar crepitus incidence, functional scores, and range of motion were recorded at each follow-up appointment. Statistical analyses were performed between the 2 groups to determine if there were differences in clinical outcomes. RESULTS The incidence of crepitus in participants implanted with the Attune was 0.55% vs 6.26% in the PFC Sigma cohort (P < .001) at 1 year vs. 0.83% vs 9.4%, respectively at 2 years post operatively (P < .001). There were small differences in extension, flexion, and Knee Society Scores between the 2 groups that were not clinically meaningful. CONCLUSION The Attune posterior-stabilized TKA demonstrated substantially less patellofemoral crepitus incidence than the historical control. We hypothesize that these findings are related to femoral component changes including a thinner and narrower anterior flange and a reduced femoral intercondylar box ratio.

What Preoperative Radiographic Parameters Are Associated With Increased Medial Release in Total Knee Arthroplasty

BACKGROUND Preoperative varus deformity of the knee is a common malalignment in patients undergoing primary total knee arthroplasty (TKA). We are unaware of any studies that have correlated how various preoperative radiographic parameters can predict the amount of medial releases performed to achieve optimal coronal alignment and ligamentous balance. METHODS A retrospective review was performed on 67 patients who required at least a medial tibial reduction osteotomy (MTRO) during primary TKA to achieve coronal balance. This patient population was matched 1:1 to another cohort of TKA patients by age, gender, and body mass index who did not require an MTRO. A radiographic evaluation was used to compare the 2 cohorts. RESULTS Preoperatively, the MTRO cohort was noted to have significantly increased varus tibiofemoral (86.12° vs 93.43°), tibial articular surface (85.79° vs 87.54°), and medial tibial articular surface angles (75.22° vs 85.34°) compared to the control cohort. The MTRO cohort had 3.13 mm of medial tibial offset and 9.06 mm of lateral joint space opening and the control cohort had 0.09 mm and 4.07 mm, respectively. The medial tibial articular surface angle and lateral joint space widening were statistically associated with the MTRO cohort. The final tibiofemoral angle in the MTRO cohort was 92.43° and was 93.40° in the control cohort. CONCLUSION The MTRO cohort was noted to have several preoperative radiographic parameters that were significantly different than the control cohort. However, the medial tibial articular surface angle and lateral joint space widening were the only radiographic parameters that were statistically associated with requiring an MTRO.

Total Knee Arthroplasty After Anterior Cruciate Ligament Reconstruction: Not Just a Routine Primary Arthroplasty.

Background: Despite the success of restoring joint stability and improving early functional outcomes after anterior cruciate ligament (ACL) reconstruction, the long-term risk of developing symptomatic osteoarthritis requiring total knee arthroplasty is higher than that in the uninjured population. The purpose of this study was to compare operative characteristics and early outcomes of patients undergoing total knee arthroplasty after ACL reconstruction with those of a matched cohort of control subjects with primary osteoarthritis and no history of ligament reconstruction. Methods: All patients who had undergone total knee arthroplasty from 2005 to 2013 at our institution with a history of ACL reconstruction and a minimum 2-year follow-up were identified from a prospective research database. These patients were matched by demographic and surgeon variables to patients who had not undergone prior ACL reconstruction. Outcomes included Knee Society Scores (KSS), range of motion, operative variables, complications, and reoperations. Results: A cohort of 122 patients was identified as the ACL study group and was compared with the matched control cohort. The mean age at the time of the surgical procedure was 58 years, and 55% of the patients were male. The mean follow-up was 3.3 years in the ACL group and 3.0 years in the control group. There was no significant difference in the latest KSS outcomes between groups postoperatively (p > 0.05). Although preoperative flexion was significantly lower (p = 0.01) in the ACL group (119°) than in the control group (123°), there was no difference between groups postoperatively. Fifty percent (61 of 122) of patients in the ACL group required implant removal at the time of total knee arthroplasty. The operative time was significantly longer (p < 0.001) in the ACL group (88 minutes) compared with the control group (73 minutes). There were a total of 11 reoperations in the ACL group, including 4 for periprosthetic infection, whereas there were only 2 reoperations in the control group. The risk of reoperation in the ACL group was more than 5 times higher than in the control group (relative risk, 5.5 [95% confidence interval, 1.2 to 24.3]; p = 0.01). Conclusions: The results of this retrospective matched cohort study suggest that prior ACL reconstruction results in longer operative time and increased risk of early reoperation after total knee arthroplasty. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Porous-Coated Metaphyseal Sleeves for Severe Femoral and Tibial Bone Loss in Revision TKA

BACKGROUND Metaphyseal bone loss is commonly encountered in revision total knee arthroplasty (TKA). Anderson Orthopaedic Research Institute types 2 and 3 defects generally require some form of metaphyseal fixation or augmentation. This study evaluates the midterm results of stepped, porous-coated metaphyseal sleeves in revision TKA in the setting of severe bone loss. METHODS Patients who underwent revision TKA using metaphyseal sleeves from March 2006 to May 2014 at our institution were identified from a prospective research database. Preoperative patient characteristics and operative data were reviewed. Postoperative outcomes were compared with preoperative values. Primary study outcomes included complications, reoperations, radiographic assessment of sleeve osteointegration, and survivorship. RESULTS One hundred sixteen knees (108 patients) underwent revision TKA with 152 metaphyseal sleeves (111 tibial and 41 femoral). Anderson Orthopaedic Research Institute defect classification included 5 type 2A, 89 type 2B, and 17 type 3 tibial defects; and 3 type 2A, 34 type 2B, and 4 type 3 femoral defects. There were 3 intraoperative fractures (1.9%) associated with sleeve preparation and/or insertion. Six knees (5 patients) were lost to follow-up and 5 patients (6 knees) died before 2 years. Of the remaining 104 knees (98 patients, 134 sleeves), mean follow-up was 5.3 years (range 2-9.6 years). Nineteen knees (16.4%) required reoperation, most commonly for recurrent infection. Only one sleeve demonstrated radiographic evidence of failed osteointegration, but did not require revision. Two sleeves (1.5%) required removal and/or resection for recurrent infection. CONCLUSION This large retrospective series illustrates the utility of porous metaphyseal sleeves in revision TKA with a low rate of intraoperative complications, excellent osteointegration, and long-term fixation.

Removing a well-fixed femoral sleeve during revision total knee arthroplasty

The following surgical technique describes a case of a 51-year-old man with severe juvenile rheumatoid arthritis that required a 2-stage revision of an infected revision total knee implant. The patient had previously been implanted with a revision rotating platform, constrained condylar device which gained excellent fixation through the use of diaphyseal-engaging stems, and a well-ingrown, fully porous-coated femoral metaphyseal sleeve. To avoid intraoperative complications while removing the femoral sleeve, a novel technique for femoral sleeve extraction was used. Using this technique, the femoral sleeve was successfully removed without intraoperative fracture or substantial bone loss.

Revision Total Knee Arthroplasty for Arthrofibrosis

BACKGROUND Arthrofibrosis after TKA is a significant cause of patient dissatisfaction. There is little evidence regarding revision arthroplasty in this patient population. The purpose of this study is to evaluate outcomes after revision TKA for arthrofibrosis. METHODS We retrospectively reviewed 46 consecutive revision TKAs for arthrofibrosis between 2007 and 2015 with minimum 2-year follow-up. Range of motion (ROM), complication rates, and Knee Society Scores (KSS) were recorded. RESULTS Patients were followed for a mean of 59 months. ROM and KSS significantly improved: with flexion improving from 88° to 103° and extension improving from 11° to 3° (P < .001). There was not a relationship between patient or surgical factors and outcomes in this study. The rate of complications was 28.2% with a 17.4% reoperation rate. CONCLUSION While revision for arthrofibrosis after TKA can be associated with significant improvements in ROM and KSS, caution is advised given high rates of revisions, reoperations, and complications. Thirty percent of patients in this series had a decrease in one or more component of the KSS or a net decrease in arc of motion after revision surgery.

Coronal alignment predicts the use of semi-constrained implants in contemporary total knee arthroplasty

BACKGROUND Semi-constrained, or varus-valgus constrained, implants are occasionally necessary to achieve stability in primary total knee arthroplasty (TKA). However, outcomes with these implants are largely unknown. Therefore, the primary goals of this study were to determine 1) can we identify preoperatively which patients might require a semi-constrained implant and 2) are there any clinical and or radiographic differences for those that require a semi-constrained implant? METHODS A multicenter retrospective study was performed to retrospectively review patients that had a Stryker Triathlon (Kalamazoo, MI) TKA with a Total Stabilized (TS) tibial insert (n=75). This TS cohort was subsequently matched 1:1 based on age, gender, and BMI to a cohort of patients with the same primary TKA design with a PS insert (n=75). Preoperative and postoperative radiographic and clinical data were compared between the two groups. RESULTS Preoperatively, the TS cohort had significantly greater varus (9.72 vs. 3.48; p=0.0001) and valgus (14.1 vs. 7.57; p=0.0001) deformity. Post-operatively, there were no statistically significant differences in revisions (p=1), reoperations (p=1), or complications (p=1). Mean clinical and radiographic follow-ups were equivalent between groups (25.5 vs. 25.8months, p=0.8851). CONCLUSION As suspected, use of a semi-constrained insert to achieve intraoperative coronal stability was most predicted by preoperative coronal deformity (either varus or valgus). Longer follow-up and larger patient cohorts are necessary to determine.

Medial tibial “spackling” to lessen chronic medial tibial soft tissue irritation

We describe a unique, utilitarian reconstructive treatment option known as tibial “spackling” for chronic, localized medial joint line pain corresponding with progressive radiographic peripheral medial tibial bone loss beneath a well-fixed revision total knee arthroplasty tibial baseplate. It is believed that this localized pain is due to chronic irritation of the medial capsule and collateral ligament from the prominent medial edge of the tibial component. In the setting of failed nonoperative treatment, our experience with utilizing bone cement to reconstruct the medial tibial bone defect and create a smooth medial tibial surface has been successful in eliminating chronic medial soft tissue irritation.

Primary total knee arthroplasty in a patient with a chronic extensor mechanism deficiency

A 44-year-old female presented with a chief complaint of left knee pain and dysfunction. The patient had a complex surgical history including patellar fracture repair, subsequent patellar ligament repair, and ultimately allograft reconstruction which was complicated by septic arthritis requiring graft resection. On presentation to our clinic, she was noted to have significant degenerative disease in addition to chronic extensor mechanism deficiency. She underwent primary total knee arthroplasty with concomitant tibial tubercle osteotomy and advancement. The patient has had an excellent result postoperatively including return of full range of motion without residual extensor lag.