A study of the role of osteotomy in unstable intertrochanteric fractures.

MM Kumar, GM Sudhakar, DD Shah, RH Pathak 
 Dr R N Cooper Hospital, Mumbai 400056.

Correspondence Address:
M M Kumar
Dr R N Cooper Hospital, Mumbai 400056.

Full Text

::   Introduction

Sliding hip screw has been shown to give better results than fixed devices for the treatment of trochanteric fractures of the femur[1],[2],[3]. Before these screws were introduced some surgeons used either a medial displacement osteotomy[4],[5] or a valgus osteotomy for unstable fractures to convert them into stable configurations. There were opposing views on the need for osteotomy, especially with the use of sliding devices. Den, Hartog, Bartal and Cookie (1991)[6], in a cadaver study, found that a valgus osteotomy increased the mean load to failure, but Chang et al[7] also using cadavers, reported that anatomical reduction increased the transmission of medial cortical load and lowered tensile strain on the plate, compared with medial displacement osteotomy. Rao et al (1983)[8] also found no benefit from medial displacement osteotomy in a retrospective study of 39 patients, but Harrington and Johnston (1973)[9], in another retrospective study supported the use of medial displacement osteotomy with a sliding screw. Clark and Robban (1990)[10] after a prospective study, suggested that anatomical reduction was, the treatment of choice, although they had more failures in this group. Desjardin et al (1993)[11] in a prospective study concluded medial displacement osteotomy offers no advantage over the anatomical reduction and supported anatomical reduction with a sliding screw plate assembly. Gargan (1994)[12] in a prospective study concluded the osteotomy gave no clear benefit over anatomical reduction with a sliding hip screw which will allow sufficient slide. Our study includes of the role osteotomy in unstable intertrochanteric fractures and merits and demerits of osteotomy.

::   Material and method

A consecutive series of 138 patients with unstable intertrochanteric fractures of the femur was treated with dynamic hip screw at a Municipal General Hospital between Jan 1992 to Dec 1994. After excluding those with multiple injuries, pathological fractures or severely arthritic knees, patients were randomly allocated to receive either anatomical or medialisation osteotomy. Both groups were followed up prospectively.

Fractures were defined as unstable by the presence of one or more of the following:

1. Four parts fracture (Dimon & Houghston, 1967)[4]

2. Medial cortical communition (Evans, 1949)[13]

3. Reverse obliquity of the fracture line (Evans. 1949)[13]

4. A large separate posterior trochanteric fragment (Dimon & Houghston. 1967)[4]

5. Subtrochanteric extension (Sarmiento and William, 1970)[14]

The socio-economic status, level of mobility, medical history, osteoporotic index (Singh & Maini 1970)[15] of all patients were recorded before and after the operation: all were followed up until fracture union of failure of fixation. In addition, the grade of surgeon, the operative time and the blood loss were recorded. Patients were mobilized as early as pain permitted usually at the end of one week.

Radiographs were taken preoperative and at first day, 6 weeks, 3 months, 6 months postoperatively and at further follow up. Fracture pattern and osteoporotic index were noted preoperatively. Post-operative radiography was measured to determine the sliding distance available and the amount of slide in each case. The implant used was a dynamic hip screw with a four holed short barrel side plate.

::   Results

Of the 138 patients initially entered in the study 18 were lost for follow up after 6 weeks, 10 patients died post operatively within 6 weeks due to associated medical illness. The remaining 110 patients were available for the follow up till fracture union of which 62 patients were in anatomical group and 48 were in medialisation group. Males were 65 and females were 45. The mean age was 58 years (Range, 28101 years). There were no significant differences in age group, gender, degree of mobility and pre operative medical illnesses in both groups. The distribution of fracture pattern were: three parts fracture were 14 patients, four part fracture 96 patients, medial cortical communition 96 patients, large separate posterior trochanteric fragment 68 patients, subtrochanteric extension in 2 patients and reverse obliquity in 3 patients. The mean angle of the plate used in anatomical group was 135 degrees whereas in medialisation it was 130 degree plate. The mean screw length in anatomical is 3.5” and in medialisation it is 2.5”. The mean operative time was 120 & 180 minutes in anatomical and medialisation respectively. Mean blood loss was 300 ml in anatomical as opposed to 500 ml in medialisation group, Junior residents operated 56 (90.3%) cases in anatomical group but operated only 15 (31.3%) cases in medialisation group. This may indicate the technical difficulty in the latter group.

In our study, the mean union rate was not significantly different in both groups. A review found no difference in pain, mobility, limping or walking distance between both groups. However, radiographs showed difference in the amount of sliding within the implant during union. The amount of sliding was recorded as settling. This differed in both groups. Settling over 10 mm was seen in 50% of anatomical cases and in only 10.1% of medialisation cases.

Out of 110 patients, 12 patients (10.9%) had failure of fixation before fracture union. 5 in medialisation and 7 in anatomical group.

In 9 cases, the screw had penetrated the joint medially, in 2 cases superior cut through the neck was found and in one case the implant broke at the screw barrel junction. These failures could be reasoned out by our analysis: they were  severe osteoporosis, improper placement of screw, implant not allowing sliding and unstable reduction.

::   Discussion

The groups were generally well matched, their fracture patterns were similar and the functional and medical outcome was also similar. Technical failure of the fixation is a serious problem in the elderly with severe osteoporosis and always requires prolonged rehabilitation. Osteotomy does not appear to reduce this. The osteotomy allows less movement at the fracture site by stable configuration supported by the evidence of only 10.15 settling more than 10 mm. But the addition of osteotomy increased the operative time and blood loss. The technique was more difficult as evidenced by that 67.7 % of all medialisation were done by senior residents or consultants. All cases of failure had identifiable reasons such as improper screw placement, unstable reduction and fixation causing loss of load sharing between the fracture fragments and the implant, severe osteoporosis, implant not allowing sliding.

There may be some fractures such as the reverse obliquity which cannot be made stable by an anatomical reduction and fixation with 135 degree hip screw or fractures where anatomical reduction cannot be obtained as per Jensen criteria[11], for these rare and small group of fractures an osteotomy or use of different implant may be appropriate.

We conclude that with the use of modern sliding hip screws, the medialisation osteotomy described by Dimon and Hughston offers no advantage over anatomical reduction. Our indication proves to be when anatomical, stable reduction as per Jensen's criteria" cannot be achieved then medialisation will be indicated otherwise, this study doesn't recommend its use routinely for the treatment of unstable intertrochanteric fractures.

References