Predicting changes in the status of patient-reported outcome measures after Birmingham Hip Resurfacing: an observational cohort study with a median follow-up of ten years.

AIMS: It is not known whether change in patient-reported outcome measures (PROMs) over time can be predicted by factors present at surgery, or early follow-up. The aim of this study was to identify factors associated with changes in PROM status between two-year evaluation and medium-term follow-up. PATIENTS AND METHODS: Patients undergoing Birmingham Hip Resurfacing completed the Veteran's Rand 36 (VR-36), modified Harris Hip Score (mHHS), Tegner Activity Score, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at two years and a minimum of three years. A change in score was assessed against minimal clinically important difference (MCID) and patient-acceptable symptom state (PASS) thresholds. Binary logistic regression was used to assess the relationship between patient factors and deterioration in PASS status between follow-ups. RESULTS: Overall, 18% of patients reported reductions in mHHS total score exceeding MCID, and 21% reported similar reductions for WOMAC function scores. Nonetheless, almost all patients remained above PASS thresholds for WOMAC function (98%) and mHHS (93%). Overall, 66% of patients with mHHS scores < PASS at two years reported scores > PASS at latest follow-up. Conversely, 6% of patients deteriorated from > PASS to < PASS between follow-ups. Multivariable modelling indicated body mass index (BMI) > 27 kg/m2, VR-36 Physical Component Score (PCS) < 51, VR-36 Mental Component Score (MCS) > 55, mHHS < 84 at two years, female sex, and bone graft use predicted these deteriorating patients with 79% accuracy and an area under the curve (AUC) of 0.84. CONCLUSION: Due to largely acceptable results at a later follow-up, extensive monitoring of multiple PROMs is not recommended for Birmingham Hip Resurfacing patients unless they report borderline or unacceptable hip function at two years, are female, are overweight, or received a bone graft during surgery. Cite this article: Bone Joint J 2019;101-B:1431-1437.

The outcome and survival of metal-on-metal hip resurfacing in patients aged less than 50 years: a prospective observational cohort study with minimum ten-year follow-up.

AIMS: The aim of this study was to report the implant survival and patient-reported outcome measures (PROMs) in a consecutive series of patients aged less than 50 years at the time of arthroplasty using the Birmingham Hip Resurfacing system (BHR), with a minimum follow-up of ten years. PATIENTS AND METHODS: A total of 226 patients with osteoarthritis of the hip, who underwent BHR and presented to a single surgeon, were included in the study. Survival of the implant was confirmed by cross-checking with the Australian Orthopaedic Association National Joint Replacement Registry. Kaplan-Meier survival curves with 95% confidence intervals (CIs) were constructed. Pre- and postoperative PROMs were compared with t-tests, and postoperative scores were compared using anchor analysis with age and gender matched normative data. RESULTS: At median follow-up of 12 years (interquartile range (IQR) 10 to 13), six BHRs were revised, with a cumulative rate of survival of 96.8% (95% confidence interval (CI) 94.2 to 99.4) at 15 years, and with a significantly lower (p = 0.019) cumulative rate of revision than the national average for the same device at ten years. Most revisions (n = 4) were undertaken early, less than three years postoperatively, and occurred in women. Patient-reported general health (Veteran's Rand-36), disease state (Western Ontario and McMaster Universities Osteoarthritis Index), function (modified Harris Hip Score) and level of activity (Tegner activity score) maintained significant (p < 0.01 for each) improvements beyond ten years postoperatively and were equal to, or exceeded, age- and gender-matched normative data in more than 80% of the patients. CONCLUSION: Longer term PROMs after BHR, from a single surgeon, for patients aged less than 50 years remain under-reported. We found that the outcome after a BHR, at a minimum of ten years postoperatively, remained satisfactory, particularly for self-reported hip function.

What happens to femoral neck bone mineral density after hip resurfacing surgery?

The major advantage of hip resurfacing is the decreased amount of bone resection compared with a standard total hip replacement. Fracture of the femoral neck is the most common early complication and poor bone quality is a major risk factor. We undertook a prospective consecutive case control study examining the effect of bone mineral density changes in patients undergoing hip resurfacing surgery. A total of 423 patients were recruited with a mean age of 54 years (24 to 87). Recruitment for this study was dependent on pre-operative bilateral femoral bone mineral density results not being osteoporotic. The operated and non-operated hips were assessed. Bone mineral density studies were repeated over a two-year period. The results showed no significant deterioration in the bone mineral density in the superolateral region in the femoral neck, during that period. These findings were in the presence of a markedly increased level of physical activity, as measured by the short-form 36 health survey physical function score.

Periprosthetic bone remodelling of a collum femoris preserving cementless titanium femoral hip replacement.

Total hip arthroplasty represents a major surgical achievement for pain relief and restoration of lifestyle quality due to the joint disease of osteoarthritis. Total hip replacement has evolved over the past 30 years utilising a variety of biocompatible materials, geometric shapes and fixation techniques. The main objective of this study is to investigate the long-term effects of strain adaptive bone remodelling due to the influence of a novel titanium cementless femoral hip replacement. The period of on-growth has been taken into account and the simulation has been run to predict the remodelling behaviour for a 36-month period. The main conclusion from this analysis is that the implant does shield the calcar to a similar degree as other cementless femoral hip designs. It does, however, tend to cause bone to be laid down along its length. This may, in part, be due to the novel geometry of the implant interlocking with and loading the bone.

Relation of neutrophil alkaline phosphatase activity to Fc IgG receptor development in human blood and bone marrow.

A possible correlation between Fc-IgG receptor expression and neutrophil alkaline phosphatase (NAP) activity was investigated in relation to maturation of granulocytes in human peripheral blood and bone marrow. NAP activity was studied in bone marrow from patients with normal peripheral blood NAP scores (20-100) and compared with those with high NAP scores. Results indicate that NAP activity is confined to segmented neutrophils (SN) in marrow and peripheral blood except when peripheral NAP activity is abnormally high. There is a normal increase of approximately 60% in mean NAP scores of peripheral blood compared to marrow SN. Granulocyte Fc-IgG receptor activity, known to increase with maturation, was studied in relation to NAP activity. A combined assay using a rosetting technique with ox-erythrocyte (oxE) antibody-IgG and subsequent NAP cytochemistry was used. Receptor expression was found to be virtually complete in normal granulocytic maturation before the appearance of detectable NAP activity. This was supported by findings in chronic myeloid leukaemia where no cases of low Fc receptor activity were found despite NAP scores of less than 5. The significance of these findings is discussed in the light of current concepts of the control of NAP activity.