Do joint registries report true rates of hip dislocation?

BACKGROUND: Despite advances in primary THA, dislocation remains a common complication. In New Zealand (NZ), dislocations are reported to the National Joint Registry (NJR) only when prosthetic components are revised in the treatment of a dislocation. Closed reductions of dislocated hips are not recorded by the NJR. QUESTIONS/PURPOSES: We compared the true dislocation rate for patients receiving primary THA in the Wellington region with the rate reported by the NZ NJR for the same group of patients. METHODS: The NZ NJR identified 570 patients undergoing primary THA from January 1, 2008, to December 31, 2009, with addresses in the Wellington region. The mean age was 67.5 years (range, 27-96 years). The minimum followup was 2 years (mean, 3 years; range, 2-4 years). RESULTS: Six patients required revision of at least one component for dislocation. There was 100% agreement between the hospital database and the NJR. Using the NJR criteria of revision of any component as an end point, the dislocation rate in the Wellington region after primary THA was 1.05%. The hospital database identified a further eight patients who presented with a dislocation of their primary THA and underwent a closed reduction. These patients were not recorded by the NJR. The true rate of all dislocations, which includes closed reductions, was 2.46%. CONCLUSIONS: This article documents the discrepancy between the NZ NJR reported rate of revision for dislocation and the true rate of dislocation in primary THA. We recommend documentation of all dislocations by NJR in their database to allow more accurate comparisons between centers and research outcomes. LEVEL OF EVIDENCE: Level IV, clinical research study. See Guidelines for Authors for a complete description of levels of evidence.

Medium-term outcome of titanium uncemented stems in revision total hip arthroplasty.

PURPOSE: To assess the medium-term outcome of titanium uncemented modular tapered stems in revision total hip arthroplasty (THA). METHODS: A questionnaire was mailed to 421 patients who underwent revision THA using a titanium uncemented modular tapered stem. 66 of whom underwent re-revision THA. The questionnaire was composed to reveal the Charnley classification, the modified 12-item Oxford hip score, and the Devane patient activity level. RESULTS: 323 (77%) of the patients responded. The mean follow-up time was 6.6 years. 12 patients underwent bilateral revision THA. The mean Oxford hip score was 35.7, compared to 35.8 for all-component revision at postoperative month 6 in the New Zealand Joint Registry. The median Oxford hip scores for the subgroups of the stem-only revision (n=92), all-component revision (n=215), and re-revision (n=16) were 38, 39.9, and 30, respectively. The difference was significant between all-component revision and re-revision (adjusted p=0.003), and between stem-only revision and re-revision (adjusted p=0.037). Regarding patient distribution according to the Charnley class and the Devane patient activity level, the difference was significant between the mean Oxford hip scores of Charnley classes B and C (adjusted p=0.017), and between the Devane patient activity levels of Charnley classes A and C (adjusted p=0.043). CONCLUSION: The medium-term outcome of revision THA using a titanium uncemented modular tapered stem was comparable to that reported for other stems.

Highly crosslinked polyethylene reduces wear in total hip arthroplasty at 5 years.

BACKGROUND: Although hip arthroplasty reliably relieves pain and improves function, problems have arisen with wear and osteolysis. Highly crosslinked polyethylene has been developed to address this problem although at present there is limited clinical evidence it does so longer term. QUESTIONS/PURPOSES: We compared the in vivo wear of standard versus highly crosslinked polyethylene (HXLP) in primary total hip arthroplasty at a minimum of 5-year followup. METHODS: We enrolled 122 patients in a prospective, double-blinded, randomized trial and followed them annually to assess their progress. Annual radiographs were analyzed using previously validated edge detection software to assess for two-dimensional, three-dimensional, and volumetric wear. The mean follow up was 5.5 years (range, 4.1 to 7 years). RESULTS: The two-dimensional wear measurements for HXLP showed lower wear compared to the conventional group (0.05 mm/year versus 0.26 mm/year, respectively). Three-dimensional and volumetric wear were similarly lower in the HXLP group. CONCLUSIONS: Highly crosslinked polyethylene undergoes substantially less wear than conventional polyethylene at medium term. The effect of hip arthroplasty longevity will need to be assessed with longer-term studies, but this may lead to a decreased need for revision as a result of less wear and osteolysis.

A double-blind, prospective, randomized controlled trial comparing highly cross-linked and conventional polyethylene in primary total hip arthroplasty.

Highly cross-linked polyethylene was developed to reduce articular bearing wear in total hip arthroplasty. In vitro studies have shown reduced wear in comparison with conventional polyethylene. A double-blind, prospective, randomized trial was performed comparing highly cross-linked and conventional polyethylene in 119 patients. The primary outcome variables were linear, 3-dimensional, and volumetric wear as determined by analysis of digitized radiographs using validated wear measurement software. Linear, 3-dimensional, and volumetric wear rates were significantly less in the highly cross-linked polyethylene group between 6 months and 4 years postoperatively (P < .05). The data presented here show that highly cross-linked polyethylene reduces short-term polyethylene wear. The intermediate and long-term clinical results of highly cross-linked polyethylene remain unknown pending further follow-up.

An investigation of patient satisfaction following discharge after total hip replacement surgery.

PURPOSE: To investigate patient expectations of and satisfaction with in-hospital discharge planning after total hip-joint replacement surgery in early and late discharge patient groups. DESIGN: A qualitative study describing patients' experience of discharge planning. SAMPLE: Thirty-three consecutive patients requiring primary total hip-joint replacement from two metropolitan hospitals. METHODS: Participants completed in-depth, semistructured interviews on the day of discharge from the hospital and again 4 to 8 weeks later. Thematic analysis of the transcripts was made after comparing data from early and late discharge groups. FINDINGS: Attendance at preassessment clinic was facilitated acceptable satisfaction levels for patients in both early and late discharge groups. Although that written information provided was timely, restricted opportunity for dialogue with health professionals limited patient knowledge and understanding of recovery. CONCLUSIONS: Multidisciplinary teams in orthopaedic practice face the challenge of finding better ways to coordinate care and ensure people undergoing total hip-joint replacement therapy surgery have individualized care. A nurse mentor-coach could be one way to ensure patients' education needs in this area are met. IMPLICATIONS FOR NURSING RESEARCH: Future studies could investigate nurses' work in discharge planning and identify any influence that their holistic approach to care could bring to a collaborative discharge process.

Proximal femoral osteotomy for the treatment of hip arthritis in young adults.

BACKGROUND: The outcome of proximal femoral osteotomy for hip arthritis in young adults performed at the Wellington Hospital (Wellington, New Zealand) was reviewed. METHODS: Seventeen patients underwent 21 proximal femoral osteotomies for the treatment of hip arthritis at Wellington Hospital between 1992 and 1999. Thirteen patients (17 hips) were contacted and were able to complete a questionnaire form specific for hip pain and function. RESULTS: There was a response rate of 76.5% (13 out of a possible 17 patients undergoing proximal femoral osteotomy) at a mean 3 years 4 months postoperatively. Of these, one patient has had a total hip joint replacement and one patient is currently on the waiting list for a total hip joint replacement. Three other patients (three hips) report moderate or severe hip pain. The remaining eight patients (12 hips) report having mild or no hip pain. Questionnaire results show a postoperative decrease in hip pain in most patients. Hip function as assessed by the questionnaire was essentially unchanged. CONCLUSIONS: Proximal femoral osteotomy is a satisfactory option for young patients with degenerative hip arthritis. The operation is only likely to be useful in the treatment of pain.

Chemical eluates from ultra-high molecular weight polyethylene and fibroblast proliferation.

Although polyethylene wear particles have been implicated in osteolysis and implant loosening, this study is the first to test whether chemical eluates extracted from ultra-high molecular weight polyethylene (UHMWPE) could also be involved in this process. Eluates were prepared from UHMWPE bar stock and examined for their effects on (3)H-thymidine incorporation by human foreskin fibroblasts grown in 96-well culture plates. Low concentrations of eluates stimulated (3)H-thymidine uptake; whereas, high concentrations inhibited uptake in a dose-dependent manner. Maximum inhibition of proliferation for eluates (87+/-0.03% inhibition, n = 45 paired wells) was greater than that observed for particles (54+/-0.07% inhibition, n = 45 paired wells). Ethylene oxide sterilization of UHMWPE reduced (3)H-thymidine uptake at low eluate concentrations relative to sterilization by gamma-irradiation. It was concluded that leachable eluates from UHMWPE implantse contribute to the osteolytic process at the bone-implant interface.

Polyethylene particles from a hip simulator cause (45)Ca release from cultured bone.

Periprosthetic osteolysis is a dominant factor in the success or failure of total hip prostheses. Polyethylene wear debris has been implicated in the process of bone resorption and subsequent implant loosening. The present study is the first to examine the effect of ultra high molecular weight polyethylene (UHMWPE) wear debris produced by a hip simulator on calvarial bone resorption in vitro. (45)Ca release was measured in cultured mouse calvarial bone samples. Although short-term exposure to UHMWPE particles (2 h) decreased (45)Ca release, longer-term exposure for 1-2 days increased release in a dose-dependent manner. After one-day exposure to 7.5 x 10(6) particles per mL, 18% more (45)Ca was released from cultured calvarial bone than from control samples. It was concluded that UHMWPE wear particles either directly or indirectly stimulated osteoclasts to activate bone resorption. Polyethylene wear debris contributes to the osteolytic process at the bone-implant interface.