Classification and Treatment of Dislocations of Total Hip Arthroplasty

Abstract

Dislocation of the femoral head from the acetabular socket is a disturbing complication for both patient and surgeon. The incidence of femoral dislocations after primary total hip arthroplasties has diminished. Dislocations still do occur, particularly with inexperienced surgeons and following revisions. This retrospective review of 39 dislocations classifies the mechanical factors responsible for dislocations and proposes a protocol for care of these patients. MATERIALS AND METHODSA computer-assisted search of hospital records disclosed 38 patients treated for 39 dislocating total hip arthroplasties; one patient had bilateral dislocations. In addition, 22 patients who did not have dislocations and who had normal functional recovery as defined by gait data were used as a control group to judge the limits of acceptable component positioning. These limits were compared with those established in the literature.'^^ Data reviewed from the charts were the patients' age, hip disease, prior operations on the involved hip, date of dislocation, reason for dislocation as identified at the time, and number of dislocations. Surgical reports were used to establish estimated femoral component position (when this was dictated). This information was collected From the for the patients had who dislocations and for the control group.Data obtained from roentgenograms were the vertical placement of the acetabular cup (theta angle); anteroposterior rotation of the cup (alpha angle); cup placement in relation to the anatomic position of the acetabulum in the pelvis; moment arm of the gluteus medius; femoral neck length; and position of the center of the femoral head. Alpha and theta angles of the acetabulum were measured by the techniques of Lewinneck et aL6 (Fig. 1); anatomic position of the acetabulum was measured by the method of Ranawat et al.' (Fig. 2); femoral neck length and center head measurements were made by the technique of Gore et al.' (Fig. 3).Cup placement was defined as superior if it was greater than 1 cm above the anatomic level or if the placement elevated the center of the femoral head 1 cm from its anatomic level. Femoral neck osteotomy was defined as excessive if the final femoral neck length was decreased by more than 1 cm from anatomic length. In none of these hips did a preoperative dislocation require excessive shortening of the femur (as with CDH). Soft tissue imbalance of the hip, ie., shortening of muscles and fascia, was considered to be present if either of the above problems existed and the trochanter had not been transplanted distally. Soft tissue imbalance also was identified if the transplanted trochanter retracted superiorly after wire breakage or escape from the wires. Both of these are referred to as trochanteric escape. The mechanisms for dislocation with soft tissue imbalance include impingement of the trochanter on the pelvis. This can occur on the posterolateral pelvis with extension and external rotation, and the hip can dislocate in extension. With flexion, adduction, and internal rotation,...

Use of a Dual Mobility Socket to Manage Total Hip Arthroplasty Instability

“…Surgery usually is recommended after a second THA dislocation [20,49]. Three categories of surgical procedures have been described [45]: nonrevision reoperation, revision procedures, and salvage procedures.…”

“…The prevalence of reoperation for instability is highly variable and is reportedly approximately 1 . 3 of the dislocating total hip arthroplasties (THAs) [2,16,20,33,59]. Because no single operative procedure can uniformly solve the problem of chronic recurrent dislocation, reoperation for unstable THA carries the highest likelihood of failure of any commonly performed reoperation after THA [9,17].…”

Myths and Legends in Orthopaedic Practice: Are We All Guilty?

“…The rate of dislocation varies from 0.5% to 11.2% [4,22,44,51,71,77,79,83,122,134,135]. Various factors contribute to a dislocation, including surgical technique, surgical skill, the type of prosthesis, alignment, surgical approach, revision surgery, and a history of neuromuscular disorders [4,22,35,77,82,134]. An exhaustive search of PubMed-indexed articles failed to reveal good evidence supporting hip precautions to decrease the rate of dislocations.…”

“…These constitute the mechanisms responsible for the posterior dislocation, which is the dominant mode of hip dislocation after THA [35,77]. Anterior dislocation occurs rarely with the posterior approach but may be the dominant mode of dislocation if the anterior approach to the hip is used [134].…”

Luxación recidivante de prótesis total de cadera

“…Las medidas postreducción van dirigidas a evitar el movimiento responsable de la luxación y a prevenir un nuevo episodio durante el período de cicatrización de la brecha capsular; para ello algunos autores [18][19][20] prefieren la colocación de una espica de yeso por un espacio de 6 semanas, o la colocación de las férulas limitadoras de la movilidad durante 12 semanas. Cada una de las propuestas especifican el porcentaje de éxito con el tratamiento propuesto.…”