(Case) 79-year-old woman. Past history, in 1989, right femur valgus osteotomy. in 1991, THA at left side. Follow-up thereafter. Hyaluronic acid injection for both knee osteoarthritis. (Clinical course)Her right hip pain getting worse and crawling indoors from the beginning of July 2013. We did right hybrid THA at August 2013(posterior approach, TridentHA cup, Exeter stem, Biolox Forte femoral head 28mm). But immediately, she dislocated twice than the third day after surgery because she became a delirium. It has been left by nurse for about 6 hours because of the midnight after the second dislocation. Next morning, check the dislocation limb position, closed reduction wasdone under intravenous anesthesia. As a result of waking up from the anesthesia, and complained of paralysis and violent pain in the right leg backward. A right lower extremity nerve findings, there is pain in the lower leg after surface about the calf, there was no apparent perception analgesia. Toe movement is weak, but the G-toe planter anddorsiflexion possible about M2, and neurological symptoms to relieved by flexion(above 70 degrees) of the right hip joint. Therefore, we thought that she suffered anterior dislocation of the sciatic nerve by the stem neck (retraction), judged to closed reduction was impossible, open reduction surgery was performed after waitingat hip flex position. But paralysis is gradually worsened during waiting surgery, toes movement had become impossible to operating room admission. Sciatic nerve is caught in front of the stem neck as expected, operative findings were able to finally reduction after removing the femoral head after dislocation. Anteversion of the cup was changed to 25 degrees from 15 degrees, and changed to 32mm diameter metal head and polyethylene liner. And we needed Intensive Care Unit(ICU) management after surgery for prevent recurrence of dislocation. Fitted with a hip brace for her, has not been re-dislocation. The sciatic nerve palsy improved in three months after the operation, the patient became able to walk without a cane.

(Summary) We experienced a rare case suffered anterior dislocation of the sciatic nerve by the stem neck, and she had a good result after open reduction surgery.

Fracture classification of femoral trochanteric fracture is usually based on plain X-ray. However, complications such as delayed union, non-union, and cut out are seen in stable fracture on X-ray. In this study, fracture was classified by 3D-CT and relationship to X-ray classification was investigated.

48 femoral trochanteric fractures (15 males, 33 female, average age: 82.6) treated with PFNA-II were investigated.

Fracture was classified to 2part, 3part(5 subgroups), and 4part with combination of 4 fragments in CT; Head (H), Greater trochanter (G), Lesser trochanter (L), and Shaft (S). 5 subgroups of 3 part fracture were (1) H+G (S: small fragment) + L-S, (2) H + G (B:big fragment) + L-S, (3) H + G-L + S, (4) H + G (W:whole) + S, and (5) H + L + G-S. Numbers of each group were as follows; 2 part: 11, 3 part (1) : 7, 3 part (2) : 12, 3 part (3) : 10, 3 part (4) : 2, 3 part (5) : 3, 4 part : 3. 3 part (3), (4), (5) and 4 part are considered as unstable, however, 6 cases in these groups were classified in A1–1 or A1–2 stable fracture in AO classification. 10 fractures in Evans and 5 fractures in Jensen classification classified as stable were unstable in CT evaluation.

It is sometimes very difficult to classify the femoral trochanteric fracture by plain X-ray. Classification with 3D-CT is very useful to distinguish which fracture is stable or unstable.

INTRODUCTION

Short femoral nail is the most popular instrumentation for femoral trochanteric fractures. PFNA is in widely use and good results are reported. In these papers, fracture classification and evaluation of surgical results were based on plain X-ray. However, some cases of delayed union, non-union, and blade cut out showed no critical problems in immediate postoperative X-ray. Cause of these complications was not able to solve in X-ray analysis. CT scan provides more information about fracture pattern and position of nail and blade. CT analysis is likely to solve the cause of these complications.