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Background There are a number of reports of polyethylene liner dissociation of third-generation modular acetabular components. This study compares our experience with 2 contemporary systems to determine whether this is an implant- or class-specific problem. Methods This is a single-center retrospective study of 961 primary total hip arthroplasties using 2 third-generation modular cementless acetabular shells: Pinnacle (535) and R3 (426) with a polyethylene liner. Details of all revisions were obtained from local databases and the New Zealand Joint Registry. Kaplan-Meier survival curves were calculated for all-cause revision, acetabular reoperation (including liner exchange), and liner dissociation. Results There were 17 revisions in group 1 (Pinnacle; DePuy Synthes): 17 for recurrent dislocation, 6 for liner dissociations (1.12%), 3 for femoral loosening, and one for deep infection. In group 2 (R3; Smith and Nephew), there were 4 revision procedures: one for infection, 2 for dislocation, and one femoral revision for periprosthetic fracture. There were significantly higher proportions revised in group 1 for all-cause revision, acetabular reoperation, and dissociation (P = .024 to 0.038). The 7-year survival for all-cause revision was 96.1% for Pinnacle and 99.0% for R3 (P = .022), and that in the acetabular reoperation group was 96.9% for Pinnacle and 99.3% for R3 (P = .035). Conclusions There was a higher revision rate for the Pinnacle acetabular component than for the R3 at 7 years. This was mainly due to polyethylene liner dissociation that can occur early or late. It appears to be a problem specific to the Pinnacle cup design rather than a feature of similar third-generation acetabular components.

Highlights • Synovial chrondroma is a rare condition of which the aetiology remains unclear. Large palpable lesions represent an atypical presentation. • The diagnosis is often not immediately apparent. However it is usually suggested by radiologic investigation and confirmed on histology. • Disease recurrence is not infrequent after excision (15–23%) and patients should be counselled regarding this. • Malignant transformation whilst uncommon has been described. At present no definite criteria exist in order to make the diagnosis of malignancy. • Due to the above risks of recurrence and malignancy, long term follow up of affected patients is advised., Introduction Synovial chrondomatosis is a rare disorder characterised by the development of hyaline cartilage from the synovial membrane. Large isolated lesions in the Hoffa's fat pad are an uncommon entity. Presentation of case A 33 year old gentleman presented complaining of progressive knee pain associated with an enlarging lesion on the anterior aspect of the right knee, with associated locking and giving way. Examination revealed a firm 4 × 5 cm lesion adjacent to the patellar tendon. Subsequent CT and MRI demonstrated a lesion in the inferior aspect of Hoffa’s fat pad, with a second lesion adjacent to the proximal tibiofibular joint, in addition to advanced degenerative changes and a meniscal tear. He proceeded to excisional biopsy. Histological analysis was consistent with a solitary synovial osteochondroma. There were no atypical features suggestive of malignancy. Discussion Synovial chondromatosis is a rare disorder affecting the synovial joints. The underlying pathophysiology is thought to be metaplastic change of the synovium to hyaline cartilaginous tissue. Transformation to malignancy has been described but is uncommon with an estimated risk of 5%. It is 1.5–2 times as prevalent in males versus females. Symptoms which patients may complain of include pain;locking and giving way; and palpable masses. The management usually entails removal of the mass lesion with or without accompanying synovectomy. Recurrence of disease may occur in up to 15–23% of patients. Conclusion Synovial chrondromatosis is a rare but well recognised condition. Long term follow up is advised in view of the risk of recurrence and malignant transformation.

Purpose.To determine factors associated with persistent sequelae after fasciotomy for acute compartment syndrome.Methods.Records of 57 men and 3 women aged 8 to 84 (mean, 31.9) years who underwent fasciotomy of the lower (n=48) or upper (n=12) limbs for acute compartment syndrome following limb trauma were retrospectively reviewed. 58 of the fasciotomies were therapeutic and 2 were prophylactic. The mean follow-up was 3.9 (range, 1–8) years. Patients were assessed through a telephone survey for persistent sequelae (parasthaesia, dysasthaesia, and/or motor weakness), using a scale of one to 4 to indicate asymptomatic, mild, moderate, and severe, respectively. Associations of persistent sequelae with the aetiology, mechanism of injury, site of fasciotomy, time to fasciotomy (from admission to anaesthesia induction), number of operations, method of closure, time to closure, and perioperative complications were assessed.Results.18 patients were asymptomatic and 42 reported having persistent sequelae including motor weakness (n=26), parasthaesia (n=28), and dysasthaesia (n=30). In terms of severity, these sequelae were mild (n=10), moderate (n=12), or severe (n=20). Persistent sequelae were associated with higher number of operations, post-fasciotomy complications, closures with skin grafting, and increased time to closure.Conclusion.To reduce the risk of persistent sequelae after fasciotomy, careful preoperative planning and meticulous perioperative care is needed to avoid multiple operations and post-fasciotomy complications. Patients whose wounds healed by secondary intention showed the best outcome.