Effect of Posterior Capsular Repair on Early Dislocation in Primary Total Hip Replacement

Background The direct anterior approach in THA requires no detachment of muscle insertions. However, damage to the short external rotator muscles may occur when attempting to elevate the femur for exposure. Although the anatomic insertions of these muscles are approximately known, there are no quantitative data regarding their locations. Questions/purposes We therefore asked where and how the tendons attach to the inner aspect of the greater trochanter. Methods In 20 cadaveric hips we identified the attachments of the short external rotator tendons on the medial aspect of the greater trochanter. Mapping of the attachment site was performed by defining coordinate axes; the total width and height of the greater trochanter represented 100% and distances of the attachment from the anteroinferior reference point were given. ResultsThe mean anterior border location of the conjoined tendon (obturator internus, gemellus superior, and gemellus inferior) attachment was located at 29% (13 mm from the anteroinferior reference point), its posterior border at 53% (23 mm), its mean superior border at 70% (15 mm), and its mean inferior border at 24% (5 mm). The mean anterior border of the piriformis tendon attachment was located at 57% (25 mm), its mean posterior border at 78% (34 mm), its mean superior border at 64% (17 mm), and its inferior border at 55% (12 mm). There was considerable variation in these attachment sites among individuals. Conclusions The insertion of the conjoined tendon extends to the anterosuperior aspect of the greater trochanter. Together with the considerable variation of the attachment site, external rotator muscles remain at risk of being damaged during the capsular release.

Section: Discussionmentioning

confidence: 99%

Anatomic Mapping of Short External Rotators Shows the Limit of Their Preservation During Total Hip Arthroplasty

Ito

Matsushita

Watanabe

et al. 2012

“…Clinical series of primary hip arthroplasty report incidences from 0.6% to 3% [9,18,26,44,46], with even higher dislocation rates in certain subsets of primary patients (such as obesity and hip dysplasia) and after revision surgery [4,7,13,16,17,20,25,27,32]. ROM before impingement is an important indicator of joint stability, and surgeons often use it as an intraoperative test to assess hip stability [3,22,33,36,37].…”

Section: Introductionmentioning

confidence: 99%

“…The type of surgical approach can have a major impact on the incidence of dislocation, with the anterolateral approach being protective against posterior dislocation [42,46]. When using the posterior approach, preserving hip rotator muscles and repairing the capsule can reduce the risk for dislocation from 4.8% to less than 1% [43,44]. Component orientation such as acetabular abduction and anteversion and femoral anteversion directly affect the joint angle where prosthetic impingement occurs [11].…”

Section: Introductionmentioning

confidence: 99%

Bony Impingement Limits Design-related Increases in Hip Range of Motion

Bunn

Colwell

D’Lima

2012

Background Factors affecting risk for impingement and dislocation can be related to the patient, implant design, or surgeon. While these have been studied independently, the impact of each factor relative to the others is not known. Questions/purposes We determined the effect of three implant design factors, prosthetic placement, and patient anatomy on subject-specific ROM. Methods We virtually implanted hip geometry obtained from 16 CT scans using computer models of hip components with differences in head size, neck diameter, and neck-shaft angle. A contact detection model computed ROM before prosthetic or bony impingement. We correlated anatomic measurements from pelvic radiographs with ROM.

“…Dislocation is one of the most frequent complications after THA with an incidence of 0.6% to 11% in the early postoperative period [10,30,32]. Factors affecting dislocation include patient characteristics, variations in surgical techniques such as placement of the implant and soft tissue repair [24], and the implant design, including the head/neck ratio [1,18,22].…”

Section: Introductionmentioning

confidence: 99%

Modular Necks Improve the Range of Hip Motion in Cases with Excessively Anteverted or Retroverted Femurs in THA

Matsushita

Nakashima

Fujii

et al. 2010

Background Anteversion of an acetabular component often is difficult to ascertain in patients with THA in whom excessively anteverted or retroverted femurs may result in limited ROM or risk of dislocation. Restriction of motion, however, is determined by the combination of version of both components. Questions/purposes We therefore determined the combined anteversion values that provide adequate ROM. We varied acetabular version by differing implantations and varied femoral version with modular necks. Methods ROM was tested by changing cup anteversion after setting the femoral version to 20°or 60°anteversion or 20°retroversion. The angle of the modular neck was adjusted in 11 increments of 5°each. Range of internal rotation (IR) at 90°flexion, external rotation (ER) at 0°e xtension, and flexion (Flex) were measured when any impingement occurred before dislocation. We defined a required ROM as having 40°IR, 30°ER, and 110°Flex. Results At 60°anteversion, ER was less than 10°even when the acetabular component was set at 10°retroversion because of posterior impingement. When a modular neck with 25°retroversion was used, ER improved to greater than 30°. At 20°retroversion, IR was 31°even when the acetabular component was opened to 35°anteversion. IR improved to 34°and 40°with 20°and 25°anteverted modular necks, respectively. Conclusions and Clinical RelevanceIn cases with excessive femoral anteversion or retroversion, the required ROM could not be achieved by simply changing the version of acetabular components. The adjustment of femoral versions using the modular necks allowed additional improvement of ROM.