Large diameter metal on metal articulations. Comparison of total hip arthroplasty and hip resurfacing arthroplasty.

The use of large diameter metal bearing total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA) increased in popularity in the last decade. More recent literature has highlighted the effect of head size in patient outcomes. Data was obtained from the Australian Orthopaedic Association National Joint Replacement Registry (AOA-NJRR) to evaluate the Birmingham (MoM) bearing surface when used with THA and HRA. There is no difference in the overall rate of revision between the THA and HRA but head size has a significant effect on revision rate. The data show that small diameter metal bearings in HRA (below 50mm) have a higher rate of revision than large diameter metal bearings in HRA (equal to and above 50mm) (P<.001). Conversely the large diameter metal bearings in THA have a higher rate of revision than the small diameter metal bearings in THA (P=.027). The revision rate for large diameter HRA compared to small diameter THA is not significantly different P=.670. We recommend caution when choosing either a large diameter (≥50mm) metal on metal THA or small diameter (<50mm) HRA.

Limited slot femorotomy for removal of proximally coated cementless stems. A 10-year follow-up of an unreported surgical technique.

We present a technique of single posterior longitudinal slot femorotomy. This technique allows the expansion of the metaphyseal-diaphyseal region of the proximal femur facilitating extraction of proximally coated uncemented femoral components while leaving the metaphysis and diaphysis intact. Since 1996 we have performed this technique in 18 revision total hip arthroplasties in 15 patients who had x-ray appearance of bony in-growth/on-growth and where found to have solidly ingrown stems at revision surgery. All were revised to a metaphyseally fitting uncemented stem. At mean follow-up of 122.4 months, there were significant improvements in both pain and function. All revised stems achieved stable boney fixation. There were no complications due to this technique. No patient developed a limp or thigh pain postoperatively. There have been no re-revisions of the stem. With appropriate patient selection, this is a simple, reliable, and extensile technique is useful to assist in the extraction of uncemented proximally coated femoral components whether hydroxyapatite-coated or not.

Cementless total hip replacements in sickle cell disease.

BACKGROUND: Sickle cell disease (SCD) affects around 80,000 people in the USA and 12,000 in the UK. Up to 40% of patients will get osteonecrosis of the femoral head. Cemented acetabular components yield poor results with the rate of osteolysis ranging from 13.5 to 46%. We report on a consecutive cohort of patients with SCD who underwent uncemented THA with ceramic-on-ceramic (CoC) bearings. METHODS: Since 2002 52 primary THAs were carried out in 40 patients. The average age was 36.1 years (17-54). 48 cases had exchange blood transfusion preoperatively and 3 had top-up transfusions.An S-ROM was used in 47 hips a Solutions stem in 4 hips and an AML in 1. It was necessary to drill the femur during 12 hips. There were 5 intra-operative peri-prosthetic fractures. 2 dislocations were observed. 2 superficial infections were detected. RESULTS: All components have in-grown. There have been no cases of radiographic osteolysis, migration or loosening of the hip with average 5-year (2-10.1) follow-up. CONCLUSIONS: The combination of a multidisciplinary team approach and uncemented implants, with ceramic-on-ceramic bearings used, has made THA in patients with SCD a safe and reliable procedure in our hospital.

Fretting and corrosion in modular-neck total hip arthroplasty femoral stems.

BACKGROUND: During total hip arthroplasty, use of a modular femoral neck on a stemmed implant allows optimization of neck anteversion, length, and offset, resulting in more accurate balance. We performed a retrospective analysis of a consecutive cohort of patients who had undergone total hip arthroplasty with a modular-neck hip system with ceramic-on-ceramic bearings. METHODS: We reviewed the results in fifteen patients who had received an ABG II dual modular hip system (Stryker Orthopaedics, Mahwah, New Jersey) from May 2007 to August 2008. Anteroposterior radiographs of the pelvis were reviewed and scored with regard to medial calcar erosion. Magnetic resonance imaging (MRI) was performed to assess for adverse local tissue reaction around the hip joint. Calcar resorption was correlated with subsequent MRI findings. Retrieval analysis was performed on the implants removed at revision. RESULTS: The mean duration of follow-up for all patients was 42.3 months (range, thirty-three to sixty months). Cobalt-ion levels were elevated in all patients; chromium levels were within the normal range. Medial femoral calcar erosion was noted in seven of the fifteen cases. All patients with grade-2 or 3 calcar erosion on radiographs had positive MRI findings consistent with adverse local tissue reaction. At the time of writing, seven patients had undergone revision arthroplasty. Intraoperatively, tissue staining with tissue and bone necrosis and pseudotumor formation were observed in all revision cases. Histological analysis confirmed the presence of metal-on-metal synovitis, with changes similar to those seen with metal-on-metal bearings. CONCLUSIONS: The ABG II dual modular hip system is associated with a high rate of early failure secondary to fretting and corrosion at the femoral neck-stem taper. The component has subsequently been recalled and is no longer in use. Surgeons using modular hip systems with a titanium stem and cobalt-chromium neck should be vigilant about annual follow-up with radiographs, and use of MRIs as indicated.

The impact of snow on orthopaedic trauma referrals.

Adverse weather has been shown to increase orthopaedic referrals and place strain on services. This retrospective study undertaken at a teaching hospital concerned referrals between April 2009 and April 2010 comparing days when snow fell to days when it did not. Referrals increased significantly on snow days (to 74.9 per day) in comparison to normal weather days (33.5 per day). During snow days there were significant increases in the number of distal radius and ankle fractures referred but not of fractured necks of femur. Complications during the snow fall period were related to procedures performed outside of the trauma unit with further difficulties related to a lack of operating equipment and implant availability. As a result of our study, we recommend that during periods of heavy snow fall orthopaedic and trauma units should place senior orthopaedic trainees in Accident and Emergency to review patients as a triage service, organise trauma lists related to surgeon specific expertise and avoid sending trauma patients outside the unit for operation.

The surgical anatomy of intra-abdominal prosthetic dislocation during hip arthroplasty.

Hip replacement surgery remains one of the most successful and common operations in modern orthopaedics. Many surgical approaches to the hip have been described. A potential anatomical weakness exists between the hip joint and the retroperitoneal space. We describe this potential space, which lies superficial to iliopsoas and its importance in hip replacement surgery. The clinical relevance of this space is illustrated by 2 cases of retro-peritoneal migration of prosthetic femoral heads and the consequences of these.