Muscular and neurologic function in patients with recurrent dislocation after total hip arthroplasty: a matched controlled study of 65 patients using dual-energy X-ray absorptiometry and postural stability tests.

Twenty-two patients with recurrent dislocation after primary total hip arthroplasty (THA) were compared with 43 randomly selected, stratified THA patients without dislocation with regard to radiographic cup position; body composition of bone, fat, and muscle (lean body mass) as determined by dual-energy x-ray absorptiometry; strength in abduction and adduction; range of motion; balance; and vibration sense. Balance and sensitivity to vibration were impaired in the patients with dislocation. No differences were found in any other variables except a subset of tall men in the dislocation group.

The prognosis and treatment of dislocated total hip arthroplasties with a 22 mm head.

We studied the risk of recurrent dislocation in 121 primary and 39 revision Charnley or Charnley hybrid total hip arthroplasties which had been treated for a primary dislocation between 1979 and 1995. Only 35% of these hips had no further dislocation or a revision for instability within one year. The rates of survival gradually declined with time or if a second, third or fourth dislocation occurred. The risk of recurrence was greater in men, but was not related to age, diagnosis, time of the first dislocation or whether the index operation had been a primary or a revision procedure. Operative treatment included 15 reoperations leaving intact components, 50 revisions, and permanent removal of the femoral stem in seven patients. The operation was successful in four patients with reoperations and in 36 who had an exchange procedure within two years. Treatment was successful in 35 of 49 hips in which it was possible to correct a technical error compared with 5 out of 16 hips in which malposition of the components was not seen (p = 0.007).

Dislocations and the femoral head size in primary total hip arthroplasty.

The dislocation rate of 3197 Charnley prostheses with 22 mm head in which the surgery was done between 1979 and 1991 in 2 orthopaedic centers was compared with that of 2875 Lubinus prostheses with 32 mm head in which the surgery was done between 1980 to 1991 in 3 other centers. A 1-year followup showed an equal rate of dislocation (2.4%-2.5%) in the 2 groups and included 75% of the 201 dislocated hips. Almost all of the late dislocations occurred with the Charnley prosthesis, resulting in a total dislocation rate of 3.7% compared with 2.9% with the Lubinus prosthesis. Regardless of the type of prosthesis used, there was a higher risk of dislocation in patients with nonhealed hip fractures and in arthroplasties performed by less experienced surgeons. When these 2 variables were removed, the small femoral head was not associated with an increased risk of dislocation. However, there were 77 of 118 (65%) recurrent dislocations in the Charnley group, compared with 37 of 83 (45%) in the Lubinus group, and the relative risk of a dislocated hip arthroplasty becoming recurrent increased by 2.3 times if the small femoral head was used. The number of reoperations also were doubled in this group. Almost 4 times as many dislocations were documented within 2 weeks after surgery after any type of prosthesis inserted through a posterior approach compared with the transtrochanteric approach, but there was no increase in rate of recurrence or revision.

Low-molecular-weight heparin (enoxaparin) as prophylaxis against venous thromboembolism after total hip replacement.

BACKGROUND: The risk of venous thromboembolism in patients undergoing total hip replacement is known to be high. However, the optimal duration of prophylaxis with anticoagulant agents after this procedure is unknown. We sought to determine whether one month of anticoagulant therapy with the low-molecular-weight heparin enoxaparin is more effective than enoxaparin therapy given only during the hospitalization for surgery. METHODS: Two hundred sixty-two patients undergoing total hip replacement received enoxaparin during their hospitalizations (average stay, 10 to 11 days). They were then randomly assigned to receive enoxaparin or placebo (131 patients each). Blinded outpatient therapy (or placebo) was continued long enough that the total treatment period, inpatient plus outpatient, was one month for each patient. Bilateral ascending phlebography was performed 19 to 23 days after discharge, with deep-vein thrombosis as the primary end point. Distal and proximal thrombosis, pulmonary embolism, and hemorrhage were also recorded, as were deaths. RESULTS: Venography was adequate in 116 patients in the placebo group and 117 in the enoxaparin group. We observed 43 episodes of deep-vein thrombosis and 2 episodes of pulmonary embolism in the placebo group, but only 21 episodes of deep-vein thrombosis and no episodes of pulmonary embolism in the enoxaparin group (incidence of thromboembolism, 39 percent and 18 percent, respectively; P<0.001). The difference in the incidence of proximal deep-vein thrombosis was also significant (24 percent and 7 percent in the placebo and enoxaparin groups, respectively; P<0.001). Six enoxaparin groups, respectively; P<0.001). Six patients in the enoxaparin group and one patient in the placebo group had hematomas at their injection sites. No patients died or had major complications. CONCLUSIONS: There were significantly fewer venous thromboembolic complications in patients undergoing elective hip replacement when prophylaxis with enoxaparin was given for a total of one month, rather than only during the hospitalization.

Surgical experience related to dislocations after total hip arthroplasty.

We studied the effect of surgical experience on the dislocation rate after 4230 primary total hip arthroplasties (THAs) all performed using the posterior approach at three orthopaedic centres at major county hospitals. There were 129 postoperative (3%) dislocations. Twice the number of dislocations were registered for inexperienced surgeons as for their more experienced colleagues. This frequency of dislocation levelled off with increasing numbers of operations and remained constant after approximately 30. For every ten primary THAs performed annually, the risk of dislocation decreased by 50%.

Influence of surgical approach on dislocations after Charnley hip arthroplasty.

Dislocations occurring in 3,199 Charnley total hip arthroplasties in two orthopaedic centers between 1979 and 1991 performed by either the transtrochanteric or posterior approach were studied. The incidence of dislocation within 2 years of surgery (2.8%), as well as the overall frequency (3.4%), did not differ between the two centers. Regardless of approach, there was a higher risk of dislocations for patients with osteoarthrosis. A logistic regression analysis, reflecting the differences in preoperative hip diagnoses and sex, indicated that the dislocation rate was not influenced by the surgical approach. More early dislocations were documented after the posterior approach, but without increases in the rates of recurrence or revision. Arthroplasties performed by less experienced surgeons through the posterior approach resulted in more dislocations.

Patient characteristics in dislocations after primary total hip arthroplasty. 60 patients compared with a control group.

To determine patient-related risk factors for dislocation after a primary Charnley hip arthroplasty, we compared 60 patients with at least one dislocation to a randomly selected group of 118 patients with no dislocation. Apart from an increased mortality rate among the patients with a dislocated prosthesis, we could not relate dislocations to any somatic and psychiatric disorder or to the use of any particular group of pharmaceuticals. However, suspicion of alcohol abuse was commoner among men in the dislocated group.

Incidence of dislocation after hip arthroplasty. Comparison of different registration methods in 408 cases.

We studied four different methods of registration of dislocations after total hip arthroplasty (THA) carried out at Malmö General Hospital during 1979-1988. Established registers failed to incorporate more than half of the dislocations and approximately one third of the patients, compared with a manual retrospective review of the original operating cords and the patient files. In 22 percent of the cases the first dislocation occurred more than one year postoperatively. Therefore different studies must use similar methods of registration concerning all details about dislocations in order to allow an adequate comparison of THA dislocation parameters.