Abstract
Introduction
Controversy exists as to whether the short external rotator tendons and capsule of the hip should be repaired after posterior approach primary total hip arthroplasty (THA). Recent studies using radiopaque markers have demonstrated that reimplantation of these muscle tendons fail early and may not prevent post operative dislocation.
Methods
Using dynamic ultrasound examination we evaluated the patency of repair in 68 tendon groups (piriformis/conjoint tendon and obturator externus). We demonstrate short and medium term success in the reimplantation of these tendons using the double transosseous drill hole technique of reattaching the tendons and capsule to the greater trochanter. We followed up 21 of our total hip replacements and 13 hip resurfacings and undertook a dynamic ultrasound examination of the external rotators by an experienced musculoskeletal radiologist to assess their integrity at a minimum of 60 days and 100 days and an average of 213 days after the operation.
Results
There were 34 hips assessed in 33 patients. 21 were total hip replacements and the rest were hip resurfacings. Each patient underwent a standard posterior approach by the senior surgeon. The piriformis and conjoint tendons (Group 1) and the obturator extenus (Group 2) were reattached with modified kessler sutures using a transosseous reimplantation technique. The capsule was reattached with a running suture using the same technique. The total hip replacement group had 16 out of 21 hips (76.2%) where both external rotator groups were intact at follow up, compared with 3 out of 13 hips (23.1%) for the hip resurfacing group (Chi-squared 9.188, p=0.002). Group 1 tendons were intact in 81% of the THR group while only in 53.8% in the rsurfaing group. We compared the hip replacement group with the hip resurfacing group using survival analysis techniques (log rank test), which take into account the different follow-up times. The hip replacement group showed a significantly longer time to the event of either rotator group not being intact at follow-up than the hip resurfacing group (log rank 5.568, p=0.018).
Conclusions
Our results do appear to suggest that this technique may be of benefit in patients undergoing primary THA but may not be as successful after resurfacing procedures. We propose that the increased incidence of external rotator detachment seen in the resurfacing group may be due to the increased strain imparted on the tendons due to the greater distance to travel, as they wind around the large resurfaced femoral head and neck as compared to the relatively thinner THA femoral neck and smaller head component.
