Minimally displaced intra-capsular femoral neck fractures in the elderly-comparison of multiple threaded pins and sliding compression screws surgical techniques

Journal of Orthopaedic Surgery, Dec 2003 by Wu, C C, Chen, W J

ABSTRACT

Purpose. To determine the outcome of treatment for minimally displaced femoral neck fractures using multiple threaded pins versus sliding compression screws for internal fixation.

Methods. The medical records of 62 consecutive elderly patients with minimally displaced intra-capsular femoral neck fractures who underwent internal fixation of the fracture (37 with multiple threaded pins, and 25 with sliding compression screws) were reviewed. Clinical and radiological assessment of fracture healing at follow-up visits were noted.

Results. In the 55 patients seen for follow-up at 3 months, 21.9% (n=7) of those treated by pinning demonstrated non-union of the fracture, and 0% of fractures treated with sliding compression screws (p=0.02). 46 patients were seen for follow-up at 1 year, with 10% (n=2) of those treated with sliding compression screws found to have osteonecrosis of the femoral head. The 2 fractures in the group treated by pinning demonstrating non-union at 3 months failed to unite by 1 year (p=0.11). 34 patients were seen for follow-up for at least 2 years, with no additional complications noted.

Conclusion. Using sliding compression screws to treat minimally displaced femoral neck fractures can achieve a higher union rate than using pinning. The reason may be the better stability in the osteoporotic bone. However, osteonecrosis of the femoral head may occur with use of sliding compression screws because of greater intramedullary vascular damage as a result of wider reaming.

Key words: hone screws; femoral neck fractures; pins, bone

INTRODUCTION

Femoral neck fractures may be caused by either high-energy or low-energy injury and are not uncommon. Most fractures are due to low-energy injury, such as from sliding down, and usually occur in elderly patients. Fractures caused by high-energy injury (e.g. from motor vehicle accidents), usually occur in young patients and are relatively rare.1

A femoral neck fracture may be intra-capsular (subcapital or transcervical) or extra-capsular (basal neck). Treatment and outcome for intra-capsular and extra-capsular lesions differ.2 Although treatment of the latter is well defined, treatment of the former remains controversial.1 Treatment of intra-capsular neck fractures in young patients by stable internal fixation as early as possible is favoured.1,2 However, for elderly patients the fracture is not uncommon, and treatment depends on fracture type and either nonoperative or operative methods may be used.3-5 Incomplete or impacted (Garden type I) fractures can be treated by non-operative methods,4 and the favoured treatment for greatly displaced (Garden type III or IV) fractures is arthroplasty.6

For minimally displaced (Garden type II) fractures, a method has yet to be consistently recommended. Multiple threaded pins or sliding compression screws (SCS) have achieved good results.7-10 Practically, in terms of anatomic and biomechanical considerations, both techniques have advantages and disadvantages. However, in our opinion, SCS should provide better holding power for intra-capsular neck fractures in elderly patients.11 To the best of our knowledge, comparison between these techniques has rarely been undertaken, and thus it remains unclear which technique is superior.8 The aim of this retrospective study was to investigate the treatment of minimally displaced femoral neck fractures using multiple threaded pins or SCS, and to determine the relative advantages and disadvantages of each technique.

METHODS

From January 1994 to December 1998, 66 consecutive elderly (>65 years) patients with minimally displaced (Garden type II) intra-capsular femoral neck fractures were treated with internal fixation at our institution. Over this period, a total of 964 elderly patients with intra-capsular neck fractures of all 4 types were treated. The incidence of Garden type II fracture was therefore 6.8%.

Extra-capsular and Garden types I, III, and IV intra-capsular neck fractures were excluded from this study. Pathologic fractures due to tumour invasion were also excluded. Inclusion criteria were age over 65 years, subcapital or transcervical fracture, low-energy injury, and Garden type II non-displaced or minimally displaced fracture. Four patients treated with cannulated screw were excluded due to the small case number. A total of 62 patients met the criteria for inclusion in the study. Subcapital or transcervical fractures were not considered separately because distinguishing between these sites on plain anteroposterior and lateral radiographs is always difficult. To distinguish between Garden types I and II, it was necessary to refer to both clinical features and radiographic findings. Generally, patients with Garden type I fractures can move and raise the ipsilateral lower extremity actively and without pain on passive movement, whereas this is not the case for patients with Garden type II fractures.3

All 62 fractures were caused by low-energy injury, either by sliding down or falling to a sitting position. 23 (37.1%) patients had associated medical conditions at the time of the injury. Hypertension, diabetes mellitus, chronic lung diseases, chronic renal insufficiency, and previous cerebrovascular accident were the most common co-morbid conditions. Patient age ranged from 65 to 94 years (mean age, 73.4 years). 13 of the patients were male while the remaining were female (n=49), with a male-to-female ratio of 1:4.