Purpose: The purpose of this study was to determine if correlation exists between acetabular cup positioning and factors relating to the surgeon and patient.

Method: Data for 2063 patients who underwent primary or revision THA from 2004 – 2008 were compiled. The post-op anteroposterior (AP) and cross-table lateral digital radiographs for each patient were obtained. The AP radiograph was measured using Hip Analysis Suite to calculate the cup abduction and version angles (version direction determined separately). Acceptable ranges were 35–45° for abduction, and 5–20° for version. Correlations were then determined with SPSS™ software.

Results: There were 1980(96%) qualifying patients. There were 1025(52%) acetabular cups that fell within the 35–45° abduction range, and 1287(70%) cups in the 5–20° version range. Regression analysis showed that the only independent predictor of acceptable abduction angle was the surgical approach (p< 0.001). Posterolateral approach was the most accurate (57% acceptability). In contrast to the posterolateral, the MIS (2 incision) approach was 3 times (95%C.I. 1.5–5, p=0.001), and the mini anterolateral approach 2.5 times (95%C.I. 1–6.5, p=0.035) more likely to have unacceptable abduction angles. The only independent predictor of acceptable version was the performing surgeon (p< 0.001), with higher volume surgeons showing greater accuracy.

Conclusion: The posterolateral approach was superior to MIS (2 incision) and mini anterolateral approaches for acceptable abduction angle, and surgeon volume influenced version angle acceptability. Further analysis on variables and their influence on cup position at a lower volume medical center would provide a valuable comparison.

Purpose: Synovial chondromatosis is a cartilaginous metaplasia that can result in multiple intracapsular and extracapsular loose bodies. Open arthrotomy has been the conventional treatment for this condition in the hip, but is associated with neurovascular embarrassment and femoral head osteonecrosis. Hip arthroscopy avoids these problems, and is a minimally invasive approach to diagnosis and treatment. Our aim was to evaluate the role of arthroscopy in the management of synovial chondromatosis of the hip at the early-to-intermediate stages of disease.

Method: Twenty-nine patients had arthroscopic treatment for synovial chondromatosis of the hip. All lesions were intracapsular and smaller than 10mm. Radiographs of the painful hip, computed tomography, and gadolinium-enhanced magnetic resonance imaging were obtained pre-operatively. During arthroscopy, loose bodies were removed via a cannula, and partial synovectomy, partial labrectomy, chondroplasty, and microfracture were done as needed.

Results: Fourteen patients were women and 15 were men; mean age was 41 years old; mean duration of symptoms was 52 months. All patients had hip pain. Mechanical hip symptoms were reported by 63% of patients. Twenty-three patients had a follow-up of at least 12 months (12 to 184 months of follow-up). Loose bodies could be seen in the imaging studies of 58% (15 of 29) of patients: 8 on radiographs and 7 with computed tomography or gadolinium-enhanced magnetic resonance imaging. At surgery, 23 of the 29 patients had torn or frayed labra. There was an average of 35 loose bodies per patient. Twenty-three of the 29 patients had femoral head changes, four of which had Grade III or IV lesions. Twenty-five of the 29 had acetabular chondral findings, ten of which had Grade III or IV lesions. Five of the 29 patients eventually underwent total hip reconstruction surgery at an average of 52 months follow-up; four of these 5 patients had at least a Grade III lesion at the time of arthroscopy. Eleven of the 23 patients who had a minimum of 12 months follow-up (12 to 184 months) had good to excellent outcomes at an average of 60 months follow-up. Complications included a case of perineal numbness and another with tingling of the foot.

Conclusion: Our patients with synovial chondromatosis of the hip benefited from hip arthroscopy. Imaging studies alone, including gadolinium-enhanced MRI, failed to establish the diagnosis in half of the patients. Diagnosis was eventually made by direct visualization of the loose bodies via arthroscopy. None of our patients had subsequent femoral head osteonecrosis or infection. For patients who had Grade I or II cartilage lesions, early diagnosis and treatment via arthroscopy helped prevent or delay the onset of secondary osteoarthritis. Arthros-copy also avoided an open surgical exposure with its associated prolonged rehabilitation. It is a valid and effective treatment for early-to-intermediate stages of synovial chondromatosis.