A Multivariate Analysis to Predict Total Hip Arthroplasty Dislocation With Preoperative Diagnosis, Surgical Approach, Spinal Pathology, Cup Orientation, and Head Size.

BACKGROUND: There are several risk factors for dislocation after total hip arthroplasty (THA), but few studies include radiographic assessment of implants, with spine pathology and patient characteristics. This study estimates the rate of dislocation by patient gender, age, race/ethnicity, body mass index, Charlson Comorbidity Index, spine pathology, prior spine fusion, levels affected, radiographic Kellgren-Lawrence score of spine osteoarthritis, THA indication, surgical approach, and femoral head size. METHODS: Seventy-six primary THA patients between January 2007 and 2020 with a dislocation were matched on age and gender to subjects without a known history of dislocation using a 2:1 allocation. Univariable and multivariable survival models that account for matched strata were used to estimate the rate of dislocation. RESULTS: Median follow-up of patients at risk for dislocation was 26.48 months (95% confidence interval [CI] 23.75-36.40). On multivariable analysis, patients with an indication other than primary osteoarthritis were 3.69 (95% CI 2.22-6.13, P < .001) times more likely to dislocate than those with osteoarthritis. Patients with a spine pathology were also nominally more likely to dislocate (hazard ratio 1.76, 95% CI 0.97-3.18, P = .06), and patients receiving a posterior surgical approach were 2.74 (95% CI 1.11-6.76, P = .03) times more likely than those receiving a non-posterior approach to dislocate. CONCLUSION: Patients with THA indication other than primary osteoarthritis and receiving a posterior surgical approach, and to a lesser degree spinal pathology, were identified as affecting the rate of dislocation. After correcting for other variables, femoral head size, cup orientation, and patient factors were not predictive. LEVEL OF EVIDENCE: Level IV, case-control study.

Cruciate-Retaining Versus Cruciate-Substituting Total Knee Arthroplasty: A Meta-Analysis.

Background: Primary total knee arthroplasty (TKA) can be performed using cruciate-retaining (CR), cruciate-substituting (CS), or posterior-stabilized (PS) total knee arthroplasty designs. While there have been many studies comparing the outcomes of CR versus PS TKA, the current literature is lacking in systematic reviews and meta-analyses that compare outcomes of CR knees versus CS TKAs. Methods: This study is a systematic review and meta-analysis of the literature comparing CR and CS knees with regard to survivorship, functional, and patient-reported outcomes, range of motion (ROM), biomechanics, and revision rate. PubMed, Cochrane, and Embase were used for the literature search, and the Modified Coleman Methodology Score was used to assess the quality of the studies. Results: Seven studies met the inclusion criteria. This systematic review and meta-analysis suggests that there are no significant differences in survivorship, ROM, or clinical knee scores between the CR and CS knees. Postoperative complications did not vary greatly between the CR and CS groups. Among the seven studies, three CR designs needed revision for either patellar crepitus, joint stiffness, or aseptic loosening of the tibial component. One CS design needed arthrotomy due to patellar clunk syndrome. Conclusion: CR and CS knees are both reasonable options for primary TKA.

Bone cutting efficiency and heat generation using a traditional fluted Burr and a novel fluteless resurfacing tool.

BACKGROUND: Powered instrumentation is often used for bone preparation and/or removal in many orthopaedic procedures but does risk thermogenesis. This study compares biomechanical properties of a fluted burr and a novel fluteless resurfacing tool. METHODS: Twenty cadaveric metatarsals were tested with four predetermined cutting forces to evaluate heat generation and cutting rate for the fluted burr and fluteless resurfacing tool over 40 s or until a depth of 4 mm was reached. Cutting rate was calculated from displacement transducer data. Heat generation was measured by thermocouples placed in the bone adjacent to the burring site. Assuming a body temperature of 37 °C, a 10 °C increase in heat was used as the threshold of inducing osteonecrosis. FINDINGS: At 1.0 N and 1.7 N, the thermal osteonecrosis threshold was reached at comparable times between burrs, while the bone removed by the resurfacing tool was on average five times greater than fluted burr at 1.0 N and over twice as great at 1.7 N. Statistical analysis of these common cutting forces showed the resurfacing tool had significantly higher cutting rates (P < 0.01). As a result, the fluted burr produced higher temperatures for the same amount of bone removal (P < 0.01). INTERPRETATION: In a cadaveric study, the fluteless resurfacing tool demonstrated higher bone cutting rates and lower heat generation for the same amount of bone removed than a traditional fluted burr.