Biomechanical evaluation of locked plating fixation for unstable femoral neck fractures.

AIMS: Evaluate if treating an unstable femoral neck fracture with a locking plate and spring-loaded telescoping screw system would improve construct stability compared to gold standard treatment methods. METHODS: A 31B2 Pauwels' type III osteotomy with additional posterior wedge was cut into 30 fresh-frozen femur cadavers implanted with either: three cannulated screws in an inverted triangle configuration (CS), a sliding hip screw and anti-rotation screw (SHS), or a locking plate system with spring-loaded telescoping screws (LP). Dynamic cyclic compressive testing representative of walking with increasing weight-bearing was applied until failure was observed. Loss of fracture reduction was recorded using a high-resolution optical motion tracking system. RESULTS: LP constructs demonstrated the highest mean values for initial stiffness and failure load. LP and SHS constructs survived on mean over 50% more cycles and to loads 450 N higher than CS. During the early stages of cyclic loading, mean varus collapse of the femoral head was 0.5° (SD 0.8°) for LP, 0.7° (SD 0.7°) for SHS, and 1.9° (SD 2.3°) for CS (p = 0.071). At 30,000 cycles (1,050 N) mean femoral neck shortening was 1.8 mm (SD 1.9) for LP, 2.0 mm (SD 0.9) for SHS, and 3.2 mm (SD 2.5) for CS (p = 0.262). Mean leg shortening at construct failure was 4.9 mm (SD 2.7) for LP, 8.9 mm (SD 3.2) for SHS, and 7.0 mm (SD 4.3) for CS (p = 0.046). CONCLUSION: Use of the LP system provided similar (hip screw) or better (cannulated screws) biomechanical performance as the current gold standard methods suggesting that the LP system could be a promising alternative for the treatment of unstable fractures of the femoral neck.Cite this article: Bone Joint Res 2020;9(6):314-321.

Correction to: Comparison of two reinforcement rings for primary total hip arthroplasty addressing displaced acetabular fractures: a biomechanical analysis.

The original version of this article unfortunately contained a mistake.

Comparison of two reinforcement rings for primary total hip arthroplasty addressing displaced acetabular fractures: a biomechanical analysis.

INTRODUCTION: Aim of this study was to biomechanically compare two different acetabular cup fixation constructs in terms of fracture fixation for displaced acetabular fractures involving the anterior column with hemitransverse fracture under partial and full weight-bearing conditions. METHODS: Two different reinforcement rings designed as cages for primary THA were biomechanically tested in terms of managing a complex acetabular fracture. Single-leg stance cyclic loading was performed to assess fracture gap movement and fragment rotation. Twelve hemi pelvis Sawbones were divided into two groups: primary THA with acetabulum roof reinforcement plate (ARRP) (n = 6) and primary THA with Burch-Schneider reinforcement cage (BSRC) (n = 6). RESULTS: During loading under partial weight-bearing (250 N) fracture gap movement tended to be larger in the BSRC group as compared to the ARRP group. Under full weight-bearing conditions, the ARRP showed 60% significantly less motion (p = 0.035) of the os ilium to os ischii gap compared to BSRC. Fracture gap movements between the os ilium and spina iliaca fragments were significantly reduced by 76% (p = 0.048) for ARRP in contrast to BSRC. The ARRP group also demonstrated significantly less movement in the fracture gaps os ischii to quadrilateral plate (62% reduction, p = 0.009) and quadrilateral plate to spina iliaca (87% reduction, p < 0.001). Significantly less rotational movement of the quadrilateral plate to the os ilium was exhibited by the ARRP group (p = 0.015). CONCLUSIONS: The presented acetabulum roof-reinforcement plate (ARRP) provides stable conditions at the acetabular component with adequate stabilization of a displaced acetabular fracture.

The role of chronic hepatitis in isoniazid hepatotoxicity during treatment for latent tuberculosis infection.

BACKGROUND: To examine chronic viral hepatitis (CVH) as a risk factor for hepatotoxicity during isoniazid (INH) treatment for latent tuberculosis infection (LTBI). METHODS: A search of MEDLINE (1966-May 2008) was conducted using the terms 'tuberculosis', 'antitubercular', 'therapeutics', 'treatment', 'prevention', 'prophylaxis', 'hepatitis', 'toxic hepatitis', 'hepatotoxic', 'liver' and 'injury'. Peer-reviewed, English-language articles describing the relationship between a history of CVH and occurrence of hepatotoxicity during LTBI treatment were selected. We limited CVH diagnoses to reports with positive serological test or biopsy for hepatitis B or C. Risk ratios and 95% confidence intervals were abstracted or derived. RESULTS: We reviewed 486 abstracts, and 11 studies met the selection criteria. Populations included in the studies were the general population (n = 6) and transplant recipients (n = 5). The variability in study designs and case finding practices precluded performing a quantitative meta-analysis. Two studies of former or current drug users reported a consistent, positive association between chronic hepatitis C infection and INH hepatotoxicity. Other risk ratios did not significantly or consistently show any association between CVH in patients treated for LTBI and the development of INH hepatotoxicity. CONCLUSION: Owing to the limited number of published papers, CVH was not established as a risk factor for INH hepatotoxicity during LTBI treatment. Controlled studies are needed to define the safety and tolerability of LTBI treatment in those with CVH and to provide an evidence base for recommendations for LTBI treatment in persons with CVH.