[The balance of the lower limb lengths in the total hip arthroplasty].

OBJECTIVE

To investigate clinical significance and surgical protocols about the balance of the lower limb lengths in the total hip arthroplasty.

METHODS

Forty-eight patients undergoing the unilateral primary total hip arthroplasty from March 2000 to October 2004 were retrospectively studied. In 12 hips, the prostheses were of the cement type; in 36 hips, of the mixture type. Thirty patients with an equal limb length had a fractured femoral neck, 10 patients had a shortened (1.0-2.0 cm) limb, 6 patients had a shortened (2.0-4.0 cm) limb, and 2 patients had a shortened (4.0-6.0 cm) limb. Based on the clinical measurement and radiographic examination, the surgical protocols were designed, the hip prosthesis type was chosen, and the neck length of the femoral prosthesis and the position of osteotomy were estimated. By the wearing of the acetabula properly, the best rotation point was found out during the operation. The cut plane of the femoral neck was adjusted according to the results of the radiographic and other examinations. The neck length was readjusted after the insertion of the prosthesis so as to achieve an intended limb-length equalization.

RESULTS

All the patients were followed up for 3-42 months. According to the Harris scoring system, clinical results were excellent in 30 patients, good in 12, fair in 4, and poor in 2. Of the 30 patients with an equal limb before operation, 5 were lengthened 1.0-2.0 cm in their lower limbs, and 1 lengthened 2. 5 cm postoperatively. Of the 18 patients with shortened limbs before operation, 10 returned to the same lengths in their lower limbs, 6 were lengthened 1.0-2.0 cm in their lower limbs, but 2 with seriously-shortened lower limbs for congenital dysplasia of the hip joint were still shortened 2.0-3.0 cm in the limb length after operation. The Harris hip scores revealed an average of 92.3 points in the patients with an equal limb length, and 88.6 points in the patients with shortened limbs.

CONCLUSION

Many factors, such as surgical protocols, prosthesis type designs, and the management techniques during the operation, can affect the limb length after operation. As the limb length discrepancy will make the patients feel disappointed, the clinical measurements are very important before operation. Application of the comprehensive appraisal methods during the operation, use of the soft tissue balance method, and skills for obtaining an equal limb length during the total hip arthroplasty are also important for improving the surgical result further.