Polyethylene liner dissociation with the Pinnacle acetabular component: should we be concerned?

Between 2007 and 2018, 535 total hip arthroplasties using the uncemented Pinnacle acetabular component (DePuy Synthes, Warsaw, IN) and polyethylene liner were implanted in our unit. Of these, 6 patients presented acutely with liner polyethylene dissociation, giving a rate of liner dissociation of 1.11%. All dissociations were atraumatic. Failure occurred at mean 37 months (range 4.5 to 130 months). Radiologically, all acetabular components were within safe zone of abduction and mean anteversion was 10 degrees (range 2-20). In one case, there was posterior impingement against the femoral neck due to femoral malalignment. All patients underwent head and liner exchange with no repeat failures. Despite excellent long-term results, the frequency of dissociated polyethylene liners is a cause of concern with the Pinnacle acetabular component.

Synovial chondroma in Hoffa's fat pad: Case report and literature review of a rare disorder.

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 4×5cm 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.

Comparison of serum Dkk1 (Dickkopf-1) and bone mineral density in patients on bisphosphonate treatment vs no treatment.

Complex pathways affect bone metabolism at the cellular level, and a balance between osteoblast and osteoclast activity is critical to bone remodeling. One of the major pathways affecting bone metabolism is Wnt/ß-catenin signaling, and its disturbances lead to a wide range of bone abnormalities. An important antagonist of this pathway is Dickkopf-1 (Dkk1). Higher Dkk1 levels have been associated with increased bone loss due to inhibition of Wnt pathway. Currently, bisphosphonates are the most commonly used agents to treat primary osteoporotic patients. This study demonstrates the effect of bisphosphonates on Dkk1 levels and its correlation with bone mineral density (BMD). Eighty patients with low BMD were recruited and divided into 2 groups of 40 each (bisphosphonate treatment group and control group). The mean Dkk1 level in the treatment group was significantly reduced to 2358.18 vs 3749.80 pg/mL in the control group (p<0.001). Pearson correlation coefficient showed negative correlation between Dkk1 and BMD at lumbar spine (r=-0.55) and femoral neck in the control group; however, no such correlation was found in the treatment group (r=-0.05). Hence, bisphosphonate therapy leads to reduction in Dkk1 levels, but it does not correlate with BMD in such patients.

Factors associated with persistent sequelae after fasciotomy for acute compartment syndrome.

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.

Cost analysis of a falls-prevention program in an orthopaedic setting.

BACKGROUND: Falls by orthopaedic patients may lead to negative outcomes such as injury, prolonged hospitalization, delayed rehabilitation, and increased costs. QUESTIONS/PURPOSES: We examined the impact of a multidisciplinary Falls-prevention Program (FPP) on the incidence of inpatient falls and fall-related injuries in an orthopaedic hospital during a 6-year period. METHODS: Patient data and fall incident report data were reviewed to identify risk factors associated with falls and fall-related injuries. A cost analysis was performed to calculate costs incurred as a result of falls. RESULTS: A total of 415 falls occurred during a 5-year period preintervention. The fall rate preintervention was significantly higher than the fall rate postintervention (3.49 versus 2.68 per 1000 bed days). Eighty-five falls occurred in the 12 months preintervention. A total of 15.29% (13 of 85) of falls resulted in minor injuries, and 9.42% (eight of 85) resulted in major injuries. The total cost incurred during this period as a result of falls was $117,754.12. Of this, 95.5% resulted from patients who sustained a hip fracture (n = 4). The total cost of implementing the FPP was $15,694.46. In the 12 months postintervention, 52 falls occurred. Twenty-five percent (13 of 52) of falls resulted in minor injuries, and 5.76% (two of 52) resulted in major injuries (no hip fractures). The total costs accrued during this period as a result of falls was $811.70. CONCLUSIONS: After implementation of a FPP, there were significant decreases in fall incidence, fall-related morbidity, and consequent costs. LEVEL OF EVIDENCE: Level III, economic and decision analyses. See the Guidelines for Authors for a complete description of levels of evidence.