Aggressive granulomatosis of the hip: a forgotten mode of aseptic failure.

PURPOSE: It has been acknowledged that implant wear correlates with the risk for periprosthetic osteolysis, being aggressive granulomatosis the worst expression of bone resorption. We sought to determine the clinical, radiological, and histological features of aggressive granulomatosis after primary total hip arthroplasty (THA). METHODS: We included nine cases with aggressive granulomatosis of the hip around cemented stems. Indications for revision THA consisted of progressive signs of extensive bone resorption or implant loosening. Mean follow-up since revision THA was 143 months (SD ± 59.4). We analysed clinical outcomes, component loosening and gross as well as histological characteristics of the granulomatous lesions. RESULTS: Overall mean time between primary THA and revision surgery was 81 months (SD ± 20.8). All of the cases evidenced multiple ovoid tumour-like lesions around the stem with extensive bone loss. Only one case reported thigh pain before revision surgery, with radiological evidence of stem loosening; the remaining cases were asymptomatic with well-fixed implants. Gross anatomy findings revealed metallosis in the femoral canal and inside the cystic lesions. Pathology analysis showed monocyte-macrophage-dominated adverse foreign-body-type tissue reaction with fibroblastic reactive zones and granulomatous inflammation. CONCLUSIONS: We found a prevalence of 1% of this aseptic mode of implant failure. Since most of the retrieved stems were not loose, we did not find any alarming clinical symptoms anticipating implant failure. In this scenario, surgeons should be aware of the rapidly progressive nature of this entity and propose a revision THA in a timely fashion.

Who Restores Hip Biomechanics More Effectively after a Femoral Neck Fracture? Comparison of Total Hip Arthroplasties Performed by Either Hip Surgeons or Orthopaedic Residents.

BACKGROUND: This study aims to analyze the ability to restore hip biomechanics in patients who undergo total hip arthroplasty for displaced femoral neck fractures operated by either hip surgeons (HSs) or orthopaedic residents (ORs). METHODS: We retrospectively compared 95 patients treated by HSs (group A) with 110 patients treated by ORs (group B). Leg-length discrepancy, femoral offset (FO), center of rotation (COR), acetabular inclination, and acetabular anteversion were evaluated on postoperative radiographs using the healthy contralateral hip as control. RESULTS: The median leg-length discrepancy was 2 mm for both groups (P = .74). The leg length was increased in 54% of the HS group and 57% of the OR group (P = .13). The median FO difference of groups A and B were 7 mm and 5.5 mm, respectively (P = .14). FO was increased in 80% of the HS group and 69% of the OR group (P = .19). Median discrepancies of the horizontal and vertical CORs were not statistically relevant, with P-values of .69 and .14, respectively. The horizontal COR was slightly medialized in 58% of the HS group and 53% of the OR group (P = .003). The vertical COR was slightly proximal in 66% of the HS group and 76% of the OR group (P = .28). The median acetabular inclination angles of groups A and B were 41° and 40°, respectively (P = .62). The median anteversion angle was 19° for both groups (P = .89). CONCLUSIONS: The horizontal COR was the only measurement with statistical significance. To conclude, ORs under supervision are as reliable as HSs to properly restore hip biomechanics in patients who undergo total hip arthroplasty for displaced femoral neck fractures.

Traumatic Dislodgement of Tibial Polyethylene Insert after a High-Flex Posterior-Stabilized Total Knee Replacement.

Many pathologic entities can produce a painful total knee replacement (TKR) that may lead to potential prosthetic failure. Polyethylene insert dissociation from the tibial baseplate has been described most frequently after mobile-bearing and cruciate-retaining TKRs. However, only 3 tibial insert dislocations in primary fixed-bearing High-Flex posterior-stabilized TKRs have been reported. We present a new case of tibial insert dislocation in a High-Flex model that shares similarities and differences with the cases reported, facilitating the analysis of the potential causes, which still remain undefined.