Horizontal fissuring at the osteochondral interface: a novel and unique pathological feature in patients with obesity-related osteoarthritis.

OBJECTIVES: Obesity is a well-recognised risk factor for osteoarthritis (OA). Our aim is to characterise body mass index (BMI)-associated pathological changes in the osteochondral unit and determine if obesity is the major causal antecedent of early joint replacement in patients with OA. METHODS: We analysed the correlation between BMI and the age at which patients undergo total knee replacement (TKR) in 41 023 patients from the Australian Orthopaedic Association National Joint Replacement Registry. We then investigated the effect of BMI on pathological changes of the tibia plateau of knee joint in a representative subset of the registry. RESULTS: 57.58% of patients in Australia who had TKR were obese. Patients with overweight, obese class I & II or obese class III received a TKR 1.89, 4.48 and 8.08 years earlier than patients with normal weight, respectively. Microscopic examination revealed that horizontal fissuring at the osteochondral interface was the major pathological feature of obesity-related OA. The frequency of horizontal fissure was strongly associated with increased BMI in the predominant compartment. An increase in one unit of BMI (1 kg/m2) increased the odds of horizontal fissures by 14.7%. 84.4% of the horizontal fissures were attributable to obesity. Reduced cartilage degradation and alteration of subchondral bone microstructure were also associated with increased BMI. CONCLUSIONS: The key pathological feature in OA patients with obesity is horizontal fissuring at the osteochondral unit interface. Obesity is strongly associated with a younger age of first TKR, which may be a result of horizontal fissures.

Anterior approach to hip replacement and associated complications: an independent review.

BACKGROUND: Direct anterior approach (DAA) to hip replacement is increasingly popular. Despite the well-published benefits of early recovery, the approach can be associated with a number of complications that may be underreported. We aim to report the incidence of some of these complications in a large retrospective case series. METHODS: 270 consecutive DAA hip replacements are studied which are performed by a single high-volume hip surgeon from 2013 to 2015, not including the surgeon's learning curve. Operation and consultation records were screened, and focused questioning via telephone was employed to capture specific complications including dislocations, wound infections, lateral femoral cutaneous nerve (LFCN) injury and revision surgery. RESULTS: 240 of 270 patients or family were contactable. The mean age and body mass index of the cohort was 66 (range 30-89) years and 27 (range 18-40) kg/m2 respectively. The mean follow-up was 3.7 years. Wound issues were encountered in 24 patients (8.8%). There were 9 dislocations (3%). 27 (10%) patients needed revision surgery in the follow-up period. Reasons for revision included leg-length discrepancies, dislocations, ongoing pain and aseptic loosening. 9 (3.4%) patients had to return to operating theatre for reasons other than revision surgery. Symptoms of lateral femoral cutaneous nerve injury was reported by 54 patients (21%). CONCLUSIONS: While the short-term benefits of DAA have been widely reported, our review shows a relatively high rate of revision surgery. We feel that the enthusiasm for DAA should be tempered until further evidence is available.