Medium Term Outcome For A Constrained Acetabular Component At A Single Institution: What Is Important For Success?

BACKGROUND: The use of constrained Total Hip Replacements (THR) is controversial due to lack of definite indications and potentially high failure rates because of mechanical loosening or component failure. A review was performed to assess a departmental use of a single constrained acetabular component over a ten years period. METHODS: Patient demographics, operative indications, complications and patient follow-up were recorded. Post-operative Oxford Hip Scores (OHS) were obtained via a combination of New Zealand Joint Registry interrogation and telephonic questioning. Cup version and inclination angles were obtained from standardised anteroposterior radiographs using established techniques. RESULTS: Forty-four constrained components (in 39 patients) were implanted between 2005 and 2014. The mean age was 78 years with mean ASA 2.7 and mean follow-up 37.2 months (range 13-116). The mean post-operative OHS was 36 (SD 9.25), and there were 4 failures (3 dislocations and 1 peri-prosthetic fracture). The 3 dislocations had either cup ante version (AV) or inclination angles (IA) outside the data set interquartile range (AV 13-24°, IA 40-50°). The cup inclination was significantly lower (p<0.01) in patients with pain on sitting. At post-operative follow-up, 14/39 patients had died from unrelated causes, with only 1 patient surviving beyond 6 years. CONCLUSIONS: Constrained acetabular components offer a solution to hip instability in a difficult group of patients. This study has shown good medium-term outcomes of a single component type in a predominantly frail group of low demand patients. Despite constraint, correct cup placement (particularly inclination) remains important to prevent dislocation or poor reported outcome.

Implants For Extracapsular Neck Of Femur Fracture Dynamic Hip Screw Versus Intramedullary Nailing.

Neck of femur fractures are the most prevalent type of injury in elderly trauma patients. Both intra and extra capsular type of fractures are equally distributed in the given population. Traditionally, Extra capsular fractures are fixed with Dynamic Hip screw or Intra medullary nailing based on the type of fracture. NICE (National Institute of Clinical Excellence) recommends fixing 31-A1 and 31-A2 fractures with DHS (Dynamic Hip Screw) whereas AO recommends fixing 31-A1 with DHS and 31-A2.1 subtype with DHS and 31-A2.2 and 31-A2.3with IMN (Intra medullary nail). In regional trauma centre 178 patients, 125 females and 53 males with extra capsular neck of femur fractures fixed were selected in a retrospective study. The data was spanning over a period of 1 year. Fractures were classified as per AO classification by two registrars. The implant selection was analysed in terms of the short term out come to find out the cost effectiveness of one over the other. The quality of reduction was assessed as per standard criteria and consideration of lateral femoral wall thickness was taken into account to assess the stability of fracture. The study found more risk of peri prosthetic fractures associated with Intra medullary nailing as compared to Dynamic Hip screw and more risk of Varus collapse was found to be associated with DHS as compared to IM Nail. Moreover, despite of Nail being costly as compared to DHS, the study did not reveal its superiority in terms of inpatient hospital stay. In appropriately selected patient DHS provides results in terms of hospital stay, revision rate and wound complications comparable to IM Nail in the short term justifying its use in the above-mentioned fracture patterns as per the standard National Institute of clinical Excellence guidelines.