Friedrich Boettner

Background: Polyethylene wear-induced synovitis and osteolysis are well-recognized complications following total knee arthroplasty (TKA) and have been of particular concern in the setting of recalled Exactech implants. While knee arthroscopy (KA) has been proposed as a minimally invasive option to address intra-articular debris and synovitis, its effectiveness in preventing disease progression and implant failure remains unclear. Purposes: The purpose of this study was to evaluate the clinical and radiographic outcomes of KA in patients with recalled Exactech TKA presenting with polyethylene wear-induced synovitis. Specifically, we assessed rates of reoperation, revision arthroplasty, and progression of osteolysis following arthroscopic intervention. Methods: A retrospective chart review was conducted on 38 patients who underwent KA after primary TKA with recalled Exactech implants between January 2022 and January 2023. Patient demographics, clinical outcomes, and radiographic and magnetic resonance imaging (MRI) findings were analyzed by a high-volume, fellowship-trained arthroplasty surgeon. Results: Within 1 year of follow-up, 4/38 patients (10.5%) underwent revision TKA, 4/38 (10.5%) patients underwent repeat KA, and 6/38 patients (15.8%) demonstrated progressive osteolysis on follow-up radiographs, resulting in an overall failure rate of 14/38 patients (36.8%). Of the remaining 30 patients who had not undergone revision TKA or repeat KA, 29 of 30 patients (96.7%) had one of the following findings: possible component loosening (5/30), progressive radiolucent lines (25/30), and worsening osteolysis on follow-up radiographs (15/30). Additionally, upon review of patient post-arthroscopy MRIs, 28/30 patients (93.3%) had documentation of persistent/progressive polymeric-induced synovitis or persistent/progressive osteolysis. Conclusion: The high failure rate reported in the current study suggests that KA with debridement is not an appropriate treatment for patients with polyethylene wear-induced synovitis and osteolysis following the implantation of a recalled Exactech TKA. Delay of the surgery can result in more severe bone defects. In patients with wear-induced synovitis but without osteolysis or implant loosening, a polyethylene insert exchange is the preferred alternative treatment. Level of Evidence: Prognostic study level IV.

Introduction: Valgus deformity occurs in approximately 15% of patients undergoing total knee arthroplasty (TKA). Soft-tissue balancing is a challenge in TKA of the valgus knee. When the knee cannot be balanced, surgeons can utilize constrained implants. The type of surgical technique may reduce the need for implant constraint. This study compares the percentage utilization of insert types in manual, robotic, and computer navigated TKA for valgus osteoarthritis. Materials and Methods: A retrospective cohort study was conducted using patients who underwent primary TKA between September 2022 and December 2023 for valgus osteoarthritis at the author's institution. Patients who have a valgus deformity >2 degrees were included. The cohort included 552 patients (manual group: 164; computer navigated group: 269; robotic group: 119 knees). The average age in the cohort was 69.9 and 409 patients (74%) were women. Results: The percentage utilization of constrained inserts in the manual, computer navigated, and robotic group was 15.2, 47.2, and 24.3%, respectively. Statistically significant differences were found for utilization of constrained inserts when comparing manual vs computer navigation (p<0.001) and computer navigated vs robotic (p<0.001). For cases with a valgus deformity between 2 deg and ≤10 deg, the utilization of constrained inserts was significantly higher in the robotic group compared to the manual group (p=0.004). There were statistically significant differences in the percentage utilization of posterior stabilized inserts between all groups (p<0.001). Differences were also found for CR implants: manual (10.4%), computer navigation (14.5%), robotic (46.2%) and medial stabilized implants: manual (1.2%), computer navigation (1.1%), and robotic (11.8%). Conclusion: Despite the fact that robotic surgery facilitates balancing of soft tissues through adjusted bone resection, computer navigated and robotic surgeons at a specialty hospital seem to have an increased utilization of constraint inserts.

Aseptic loosening is one of the main causes of failure for both primary and revision total knee arthroplasty (rTKA). Bone loss and bone quality can vary significantly across anatomical regions, potentially challenging long-term fixation. In recent years, zonal fixation in rTKA has become increasingly popular; this approach divides areas of fixation based on anatomy into 3 zones: epiphysis, metaphysis, and diaphysis. This system emphasizes the importance of preoperative planning and encourages surgeons to carefully select the fixation method for each respective zone. To plan proper fixation, adequate imaging is required to document bone defects and areas of sclerosis. While anteroposterior and lateral radiographs remain the gold standard for defect classification, computed tomography imaging has facilitated 3-D defect evaluation and bone density assessment. For many years cemented and hybrid fixation have been the main modes of fixation in rTKA, but recently these modes of fixation have been augmented by the use of uncemented cones and sleeves. Through bone ingrowth this type of fixation provides lasting fixation in the metaphysis and seems to reduce the need for longer stem fixation in the diaphysis. This narrative review provides an overview of advanced imaging techniques, defect grading, and principles of implant fixation using the concept of zonal fixation.

Introduction Hip instability and dislocation post-THA is a prevalent complication leading to revision surgeries. Patients are considered “high-risk” if the sit-to-stand sacral slope change is less than 10 degrees. The current study analyses if lateral radiographs and EOS imaging result in similar measurements and identify the same at-risk patients. Materials and methods In a retrospective study consisting of 59 hips (58 patients), spinopelvic measurements were obtained from lateral sitting and standing pelvic radiographs and EOS sitting and standing (whole body) films taken during the same preoperative assessment. Measurements on each images set were performed to assess variation in measurements between the two modalities. Results The average measured sacral slope difference between the two imaging methods was 4.5° (standing) and 6.6° (sitting), with a sit-to-stand difference of 7.2°. Lateral radiographs identified 16 patients at high-risk for dislocation and EOS identified 15 high risk patients; however, only 9 patients overlapped between the two modalities. There was a significant postural difference between the two modalities: average spinal angle difference was 10.4°(p= 0.0026).and femoral angle off the horizonal was 7.4°(p= 0.16). Conclusion There are discrepancies between EOS and conventional lateral radiographs in measuring sacral slope and change in sacral slope from sitting to standing and both imaging modalities might identify different high-risk patients for dislocation. Efforts need to be made to standardize the patients’ position at the time of imaging.

Introduction Intra-articular steroid injections (IASI) and knee arthroscopies are occasionally performed after total knee arthroplasty (TKA) in patients with persistent pain, inflammation, or mechanical symptoms. Prior studies have raised concern regarding a potential increased risk of periprosthetic joint infection (PJI) following such procedures. Comparative data on infection rates across these post-TKA interventions remain limited. This study evaluates and compares the incidence of PJI in patients who underwent IASI, knee arthroscopy, or both following primary TKA. Materials and methods A retrospective cohort study was conducted using patients who received primary TKA between January 2017 and January 2023. PJI was defined according to the 2018 Musculoskeletal Infection Society (MSIS) criteria. Infection rates were compared using Fisher’s exact test. The control group was propensity score matched on a 5:1 ratio independently for IASI and knee arthroscopy based on age, sex, ASA score, Charlson comorbidity index, and surgical date. Results 362 patients (372 knees) met inclusion criteria for the treatment groups: 173 received steroid injection only (group 1), 142 underwent arthroscopy only (group 2), and 57 received both (group 3). When comparing all treatment groups (1.34%) to the matched control group of 1850 patients (0.97%), there was no significant difference between infection rates (p = 0.5708) at a minimum 2 year follow up. The infection rate in group 1 was 1.73%, in group 2 was 0.70%, and in group 3 was 1.75%. Two of the 3 infections in group 1 occurred within 30 days of IASI. The 6 month PJI rate in the 230 knees receiving IASI (group 1 and 3) was 0.87%. Conclusions The fact that two infections occurred within 30 days of IASI suggests a slightly increased risk of infection after IASI. However, reported PJI rates within 6 months of IASI and Arthroscopy are very low and both are considered reasonable treatment options in selected patients.

Background/Objectives: While most patients resume sports within one year after total knee arthroplasty (TKA), data on whether patients achieve their desired level of sports activity remain limited. This study aimed to evaluate the relationship between desired sports activity levels and postoperative outcomes after TKA and to identify factors associated with achieving the desired activity level. Methods: This retrospective cohort study included 280 patients (63.9% female; mean age, 65.7 years) who underwent primary TKA with a mean follow-up of 28.2 months. The University of California and Los Angeles (UCLA) activity score was used pre- and postoperatively to assess the desired and the achieved activity level. Results: The mean UCLA activity score improved significantly after surgery (from 4.6 to 5.6; p < 0.001). However, the mean preoperative desired UCLA score was significantly higher than the mean postoperative achieved UCLA score (7.1 vs. 5.6; p < 0.001). Overall, 34.6% of patients reached their desired activity level. These patients demonstrated a significantly lower preoperative desired UCLA score (6.1 vs. 7.6; p < 0.001) and a higher postoperative achieved UCLA score (6.7 vs. 5.0; p < 0.001) compared with patients who did not. Male sex, higher preoperative UCLA scores, and lower preoperative desired UCLA scores were identified as independent predictors of achieving the desired activity level. Conclusions: The present study demonstrated that despite excellent Knee Society function and WOMAC scores only 1/3 of patients reach their sport-related desired activity level. Surgeons must ensure that they communicate realistic expectations to patients prior to surgery, in order to avoid dissatisfaction that may arise from unmet expectations.

Surgical treatment for osteoarthritis of the hip includes hip resurfacing (HR) and total hip arthroplasty (THA) via various surgical approaches. The discus