Session IV - Geriatrics

Minimally Invasive Dynamic Hip Screw: Randomized Comparison to Conventional Technique

Edward J. Harvey, MD¹; Abdullah al-Obaid, MD¹; Graham Elder, MD¹; Anna Passariello, MD¹; Pierre Guy, MD²;

¹McGill University, Montreal, Quebec, Canada;

²University of British Columbia, Vancouver, British Columbia, Canada

Purpose: We evaluated whether a minimally invasive technique for hip fracture fixation was comparable to a conventional technique.

Method: Angiograms determined a "safe" zone for blind dissection. A surgeon-randomized blinded follow-up design was used to compare the two techniques. A single surgeon used a minimally invasive dynamic hip screw technique for all intertrochanteric fractures. The outcome was compared to that of patients collected in a consecutive fashion who underwent a conventional technique. All patients used identical rehabilitation physiotherapy protocols. An assistant blinded to the hypothesis and operation received collected data. The measured outcomes included postoperative hemoglobin loss, operative time, time to ambulation, pain scales, and complications.

Summary of Results: Angiography. The angiogram review showed that the average distance from the lower edge of the trochanteric flare to the first significant branch averaged 9.3 cm (standard deviation, 0.76; range from 8.0 to 10.1 cm). This established a "safe" zone for minimally invasive surgery.

Clinical. After randomization of consecutive patients over a 6- month period, 21 patients were placed in the minimally invasive group and 27 in the control group. Patients were not different from each other in preoperative demographics or co-morbidities. Surgical time (29 vs. 70 min, P <0.001) and hemoglobin drop (22.3 vs. 29.3 g/dL, P <0.001) were significantly better in the minimally invasive group than among those treated with the conventional technique. Postoperative pain (Total morphine use) was not statistically significant (minimally invasive, 15.1 mg [range, 0 to 62.5]; conventional technique, 25.2 mg [range, 0 to 90 mg], P = 0.1). A power calculation showed that the study would have required N = 60. Visual Analog Pain Scale scores and days to walker ambulation tended to be higher for those treated with conventional technique, but the level did not reach statistical significance.

Conclusions: Use of a minimally invasive dynamic hip screw is a safe, reproducible technique that permits use of standard plates but decreases operative time, operative blood loss, time to ambulation, and postoperative pain.

Significance: The use of the minimally invasive dynamic hip screw technique allows a reduction in iatrogenic factors that increase patient morbidity and add to hospital costs. This is of benefit to the patient, the surgeon and the health system.