Dislocation in primary total hip arthroplasty is common and problematic and is attributable to several factors, including previous hip surgery, neuromuscular disorders, cerebral dysfunction, psychosis, alcoholism, and female gender. Factors under the control of the surgeon include component orientation and restoration of soft-tissue tension. Prosthetic factors lowering the risk of dislocation include increasing the size of the prosthetic femoral head, keeping femoral neck circumference to a minimum, and optimizing the geometry of the acetabular component. Postoperatively, patients should be expected to comply with standard hip precautions. Treatment is with immediate closed reduction. Multiple dislocations can be treated by advancing the trochanter in the presence of inadequate soft-tissue tension, revision arthroplasty in the presence of malpositioned components, or the use of a constrained cup when intraoperative instability persists. Because the risk of redislocation is much higher than that for first-time dislocation, prevention is critical. An enhanced repair technique can be used to reconstruct the posterior soft-tissue sleeve during the posterior surgical approach. This technique has been successful in lowering the dislocation rate from 4% to 0% in a series of 395 consecutive patients.
"At present, the BMP family has more than 20 members, of which BMP-2, BMP-4, and BMP-7 have the strongest activity and can promote the formation of cartilage and new bone. Promoting the fusion of bone and spine has been successfully undertaken (Woo and Morrey, 1982; Mahoney and Pellicci, 2003). In these experiments, BMP-4 and BMP-7 have been shown to play various roles in promoting the fusion of bone and spine (Berry et al., 2004; Meek et al., 2006). "
[Show abstract][Hide abstract] ABSTRACT: The biological effects of transfection of an adeno-associated virus (AAV) vector with bone morphogenetic proteins 4 and 7 (BMP-4/7) fusion gene (AAV-BMP-4/7) were determined in rabbit bone marrow stromal cells (BMSCs). BMP-4 and BMP-7 genes were obtained through one-step reverse transcriptase polymerase chain reaction from human placental cells. The BMP-4/7 fusion gene was then generated through recombination. Rabbit BMSCs were transfected with the recombinant AAV vectors carrying AAV-BMP-4/7 with multiplicity of infection values. Cell growth curves were drawn to evaluate the biological effects of AAV-BMP-4/7 on cell activity. The transfection efficiency was measured using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The ossification of cells was evaluated by observing alkaline phosphatase (ALP) and osteocalcin (OC) activity after transfection for 7 and 14 days. The cells were then transfected with AAV-BMP-4/7 and AAV-enhanced green fluorescent protein. We successfully constructed the recombinant adeno-associated virus with the BMP-4/7 fusion gene. The transfection efficiency of AAV-BMP-4/7 was approximately 72% without significant biological effects on cell activity. Cell ossification was significant after transfection with AAV-BMP-4/7. The 1 x 10(5) vg/cell multiplicity of infection value of transfection efficiency was more than 5 x 10(4) vg/cell (59.38%). Significantly higher ALP and OC activity occurred in the AAV-BMP-4/7 transfection groups than in the AAV-enhanced green fluorescent protein groups (t(ALP) = 896.88, P < 0.001; t(OC) = 543.24, P < 0.01). The AAV-BMP-4/7 fusion gene can highly efficient transfect rabbit BMSCs cultured in vitro and it has significant ossification activity.
"Although total hip arthroplasty (THA) remains the cornerstone of surgical treatment for degenerative joint disease, dislocation continues to be a relatively common complication, and is second only to late prosthetic loosening.1 Approximately 80% of dislocations following THA occur in the posterior direction with a reported incidence of 0.7% to 5.5% following primary surgery and of 5% to 20% following revision.2 "
[Show abstract][Hide abstract] ABSTRACT: Minimally invasive (MI) total hip arthroplasty (THA) is an alternative to standard THA, but has created much controversy among orthopedic surgeons. The authors modified the original minimally invasive two-incision THA technique and used large-diameter (32 mm, 36 mm) ceramic-on-ceramic articulation.
One hundred and seventy patients that underwent unilateral MI two-incision THA were retrospectively reviewed, and surgical morbidity, functional recovery, radiological properties, and complications were assessed.
Mean Harris hip score (HHS) improved from 41.8 to 96.1 at last followup, and mean Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score from 66.2 to 26.9. The mean lateral opening angle of the acetabular component was 38.2° and the mean stem position was valgus 1.9°. There was an intraoperative femur fracture and one revision surgery due to stem subsidence. No patient had dislocation.
Our data suggest that this modified technique combined with large ceramic femoral head is safe and reproducible in terms of achieving proper implant positioning and early functional recovery.
Indian Journal of Orthopaedics 03/2012; 46(1):29-35. DOI:10.4103/0019-5413.91632 · 0.64 Impact Factor
"In 1982 Woo and Morrey reviewed 10,500 primary THAs and identified an overall dislocation rate of 3.2% . Later studies have reported a rate of 2–5% [2, 3]. Some hips dislocate more than once, and patients with recurrent dislocation have reported a worse outcome than after uncomplicated THA [4, 5]. "
[Show abstract][Hide abstract] ABSTRACT: Dislocation after primary total hip arthroplasty (THA) is a significant complication that occurs in 2-5% of patients. It has been postulated that increasing the femoral head diameter may reduce the risk of dislocation. The purpose of this paper is to report our experiences with a change from a 28 to a 32-mm femoral head.
The retrospective cohort study includes 2572 primary THA performed with a 28 or 32 mm diameter femoral head in the period February 2002 to July 2009. All patients were operated with a posterolateral approach, and all except 18 were operated because of osteoarthritis. Cemented stems were used in 1991 cases and uncemented stems in 581 cases. Cemented cups were used in 2,230 cases and uncemented cups in 342 cases. The patients have been routinely followed for 1-8 years in the 28-mm femoral head group and from 0.5-7.5 years in the 32 femoral head group. We defined a dislocation as an event in which the hip required reduction by a physician.
Dislocation occurred in 49 hips with a 28-mm femoral head and in 4 hips with a 32-mm femoral head with an odds ratio of 6.06 (95% CI = 2.05-17.8) (P < 0.001). Otherwise, there were no significant associations between sex, age, diagnosis and type of prosthesis.
Multivariate analyses of patients operated at our hospital indicate a significant association between femoral head diameter and dislocation after THA. There were no significant associations between dislocation and sex, age, diagnosis, or type of prosthesis.
Journal of Orthopaedics and Traumatology 06/2010; 11(2):111-5. DOI:10.1007/s10195-010-0097-8
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