Distal Femoral Replacement versus Operative Fixation for Periprosthetic Distal Femur Fractures: A Systematic Review and Meta-Analysis.

BACKGROUND: Open reduction and internal fixation (ORIF) and distal femoral replacement (DFR) have been utilized in the management of periprosthetic distal femur fractures. At present, much of the literature has been limited to small retrospective series. The purpose of the current investigation was to present the results of pooled data to determine the complication rates associated with ORIF and DFR. METHODS: Publications from 2010 to 2020 describing 10 or more periprosthetic distal femur fractures treated with ORIF (ie, single plate, intramedullary nail, and dual fixation) or DFR were included, resulting in 32 publications and 1,258 fractures (977 ORIF and 281 DFR). Occurrence of surgical complications, reoperations, and medical complications were evaluated and compared. RESULTS: The rate of surgical complications (ORIF versus DFR, 20.5 versus 14.9%, P = 1.0) and reoperations (12.9 versus 12.5%, P = 1.0) following DFR were similar. However, pooled analyses demonstrated that patients treated with DFR had a higher medical complication rate (ORIF versus DFR, 8.5 versus 23.1%, P = .0006). CONCLUSION: ORIF and DFR for the treatment of periprosthetic distal femur fractures have similar surgical complication and reoperation profiles. While this review found an increased rate of medical complication following DFR, there are limitations in quality reporting in the literature, which should be considered when interpreting the study's findings. Failed ORIF can be salvaged with DFR, but the difficulty of this reoperation is dependent on the ORIF technique that was used. With future prospective studies, this review can help guide management of these fractures.

Synovial Cell Count Poorly Predicts Septic Arthritis in the Presence of Crystalline Arthropathy.

Introduction: A synovial cell count greater than 50,000/mm3 is the threshold most commonly used to diagnose septic arthritis. This lab value may be nonspecific in the setting of crystalline arthropathy. The purpose of this study was to evaluate the accuracy of diagnosing septic arthritis using a synovial cell count cut-off of 50,000/mm3 in the setting of crystalline arthropathy. Methods: This was a retrospective review of joint aspirations performed between July 1st, 2013 and June 30th, 2016. Synovial fluid samples were evaluated for cell count, crystals, Gram stain, and culture. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the synovial markers were calculated. Results: During the study period, 738 joint aspirations were sent for testing, of which 358 aspirations in 348 patients met inclusion criteria. There were 49 (13.7%) cases of culture-positive septic arthritis, and 47 patients underwent surgical irrigation and debridement. Gout and pseudogout crystals were present in 163 aspirates (45.5%). Three joints (0.8% overall rate) had concomitant crystalline arthropathy and septic arthritis, each of which had a synovial WBC ≥85,000/mm3. Increasing the WBC count cutoff to 85,000/mm3 demonstrated a specificity of 100%, but a PPV of 12.0%. Conclusions: A cut-off of 85,000/mm3 may be more appropriate to diagnose concomitant septic arthritis and crystalline arthropathy. We recommend medical management and observation in patients with crystal-positive joint aspirations unless the synovial cell count is elevated above 85,000/mm3. Prospective studies using this treatment guideline are needed to evaluate its validity and accuracy.

The Assessment of Limb Length Discrepancy Before Total Hip Arthroplasty.

INTRODUCTION: The clinical relevance of limb length discrepancy (LLD) after total hip arthroplasty gains attention as the number of total hip arthroplasties increases. Although several techniques are commonly used to assess LLD using a pelvic radiograph, their accuracy is not well established. This study measures LLD using different techniques viewing the pelvis and compares the measurements with the true LLD. METHOD: Pelvic landmarks used included the femoral head, lesser trochanter, acetabular teardrop, ischial tuberosity, and tibial plafond. The true LLD was determined by finding the difference in distance between the lowest point of the ischial tuberosity and the tibial plafond as well as the top of the femoral head to the center of the tibial plafond for each lower limb. RESULTS: Using pelvic landmarks to assess LLD is significantly different (P < .001) from the true LLD. The difference in distance from the center of the tibial plafond to the ischial tuberosity was not significantly different from the measurement from the top of the femoral head to the center of the tibial plafond (P = .08). Also, using the acetabular teardrop as a landmark has less reliability when compared to the ischial tuberosity. DISCUSSION: Owing to the extensive variety of pathologies that are associated with LLD, preoperative planning should include an assessment of any preexisting LLD. Although it may be reasonable to compare pelvic measurements preoperatively and postoperatively to assess for changes, the data from this study do not support the estimation of the true LLD using a pelvic radiograph.

Using the Anatomical Axis as an Alternative to the Mechanical Axis to Assess Knee Alignment.

The treatment of knee osteoarthritis and the preparation for total knee arthroplasty require repetitive imaging to guide preoperative planning and operative technique. Full-length standing anteroposterior images are the gold standard in assessing the alignment of the limb via the measurement of the mechanical axis of the knee. The anatomical axis can be obtained from a more limited image of the knee, and as such is less expensive and exposes the patient to less ionizing radiation. The objective of this cross-sectional prospective study was to examine the extent to which the anatomical axis measured on a fixed-flexed posteroanterior (Rosenberg view) radiograph correlates with the mechanical axis. The data of 209 total knee arthroplasty radiographs were analyzed to compare the preoperative correlation between the mechanical and anatomical axis. The anatomical axis correlated with the mechanical axis when it was measured from both the standing full-length anteroposterior radiograph and from a fixed-flexed posteroanterior radiograph. Using an angle of offset found from linear regression, these correlations become closer. Body mass index and Kellgren-Lawrence grade were not found to have a significant effect. It is the conclusion of this study that the anatomical axis, as measured from a limited knee radiography, may serve as a plausible estimate of the mechanical axis when done with a neutral angle of offset, and that offset angle depends on gender and the imaging technique used to determine the anatomical axis.