[Application of Tri-Lock bone preservation stem in acetabular protrusion combined with shorten defect of femoral head and neck].

Objective: To evaluate the manipulation technique and clinical outcome of Tri-Lock bone preservation stem for acetabular protrusion combined with shorten defect of femoral head and neck.

Methods: From January 2013 to December 2015, 10 patients(12 hips) with acetabular protrusion combined with shorten defect of femoral head and neck were treated with total hip arthroplasty(THA) including 5 males and 5 female with an average age of(51.6±3.0) years old ranging from 42.5 to 67.5 years old. The acetabular prostheses were all biological prosthesis with the ceramic lining, the whole ceramic femoral head was used in all the cases. The posterior-lateral hip incision was adopted in the surgery. The follow-up was carried out in 12 months after the surgery, and later once a year. The Harris score system in growth of femoral side described was used to assess the joint function of the patients before and after the surgery.

Results: Ten patients were followed up for 8 to 48 months with an average of 33.0±3.5. All the incisions healed well and there were no complications such as femoral fracture, infection, dislocation and neurovascular injuries. The biological compression of the acetabulum and the stem of the femur was realized immediately after operation in 10 patients(12 hips). X-ray at 3 months after the operation showed bone growth were extended in a wide range, which could achieve bone fixation, no loosening and re-invagination. The range of hip movement increased from (45.8±7.5)° to (90.0±6.5)° at the final follow-up, with flexion increased to (89.0±6.0)°, abduction increased to (35.5±7.3)° and internal rotation increased to(31.8±6.6)°, the outer rotation increased to(32.6±5.2)°. The mean Harris scores had improved from 45.7±7.5 pre-operatively to 93.5±8.0 post-operatively, there was statistically significant difference between before and after surgery (=144.832, <0.05).

Conclusions: Combined with acetabular treatment, Tri-Lock bone retention of the femoral stem in the treatment of femoral head and neck with shortening of the acetabular retraction and severe hip joint soft tissue contracture in patients, could be well pressed and retained more bone. The reconstruction of the acetabulum and the delamination of soft tissue are required during the operation. The results were safe and satisfactory in the middle and short term follow-up.