All patients with a MOM THR implanted at our unit were recalled for clinical examination, Oxford hip score, radiographs, MARS MRI and cobalt/chromium ion levels. Patients were sub-classified, determining further follow up: a regular screening programme or referral to a revision arthroplasty surgeon. We identified 299 MOM THR's. 59 patients reported a recent deterioration in symptoms. 67 had an abnormal x-ray. 232 hips underwent MARS MRI: 66 showed mild MOM disease, 31 moderate MOM disease, 17 severe MOM disease. 117 had a substantial fluid collection around the hip. Serum cobalt/chromium ions were raised in 135 patients. 46 had one or both above 7 ppb. 148 THR's were referred to a revision surgeon. 21 have been revised and 14 are awaiting revision. In total 64 hips have been revised. 13 were histologically proven ALVAL, 19 had clinical findings of ALVAL (not histologically confirmed), and 1 non-specific reaction to metal wear. 53 asymptomatic patients had evidence of soft tissue reaction on MRI and/or rising metal ions. Our screening programme identified asymptomatic patients with evidence of a suspicious reaction to their MOM THR. We recommend all patients with a MOM THR are fully screened for ARMD regardless of symptoms and metal ion levels.
Higher than expected revision rates have been observed in large bearing metal-on-metal total hip replacements. We have introduced a metal on metal hip screening clinic at our unit and report the results. All patients who had a metal-on-metal total hip replacement implanted at our unit were recalled to clinic. Screening consisted of clinical examination, Oxford hip score, radiographs, MARS MRI and serum cobalt/chromium ion levels. MRI scans were graded (Norwich Classification) by a single consultant radiologist who was blinded to the history, examination, and metal levels. Patients were sub-classified into 6 groups, which determined further follow up and were either entered into a regular screening programme or referred to a revision arthroplasty surgeon for a decision on whether revision was requiredBackground:
Methods:
Hip resurfacing arthroplasty (HRA) in patients with a varus deformity of the femoral neck-shaft angle (NSA) is associated with poorer outcomes. Our experience has not reflected this. We examined the Oxford Hip Scores (OHS), Harris Hip Scores (HHS) and outcomes of patients with varus hips against a normal cohort to ascertain any significant difference. We identified 179 patients. Measurement of the femoral neck-shaft angle was undertaken from antero-posterior radiographs pre-operatively. The mean NSA was 128.5 degrees (SD 6.3). Patients with a NSA of less than 122.2 were deemed varus and those above 134.8 valgus. These parameters were consistent with published anatomical studies. The varus cohort consisted of 23 patients, mean NSA 118.7 (range 113.6-121.5), mean follow-up 49 months (range 13-74). Mean OHS and HHS were 16 and 93.5 respectively. Complications included 2 cases of trochanteric non-union; no femoral neck fractures, early failures or revisions. Normal cohort consisted of 125 patients, mean NSA 128 degrees, mean follow-up 41 months (range 6-76). The OHS and HSS were 18.8, 88.9 respectively. Complications included 5 trochanteric non-unions and 1 revision due to an acetabular fracture following a fall. Statistical analysis demonstrated no statistical difference between the cohorts OHS (p=0.583) or HHS (p=0.139). Our experience in patients with a varus femoral neck has been positive. Our analysis has demonstrated no statistical difference in hip scores between the cohorts. We have not yet experienced any femoral neck fractures, which we believe is due to the use of the Ganz trochanteric flip and preservation of blood supply.
Hip resurfacing arthroplasty (HRA) in patients with a varus deformity of the femoral neck-shaft angle (NSA) has been cited in the literature as contributory factor towards a poorer outcome. Our experience has not reflected this. We examined the outcomes of patients with varus hips against a normal cohort. Measurement of the femoral neck-shaft angle was undertaken from standard antero-posterior radiographs pre-operatively. The mean NSA was 128.5 degrees (SD 6.3). Patients less than 122.2 were deemed varus and those above 134.8 valgus. These parameters were consistent with the published literature. The varus cohort consisted of 23 patients, mean NSA 118.7 (range 113.6-121.5), mean follow-up 49 months (range 13-74), mean OHS & HHS, 16 & 93.5 respectively. Complications included 2 cases of trochanteric non-union; no femoral neck fractures or revisions. The normal cohort consisted of 125 patients, mean NSA 128 degrees, mean follow-up 41 months (range 6-76), mean OHS & HSS, 18.8 & 88.9 respectively. Complications included 5 cases of trochanteric non-union and 1 revision. Statistical analysis demonstrated no difference between the cohorts OHS (p=0.583) or HHS (p=0.139). Our experience in patients with a varus femoral neck has been positive. Our analysis has demonstrated no difference in outcomes between the cohorts.
