Fri., 10/9/09 Hip & Geriatric, Paper #45, 11:11 am OTA-2009
A Randomized, Prospective Comparison of the DHS and DHHS Implants for the Treatment of Pertrochanteric Hip Fractures Performed in the Community Setting
Daniel C. Fitzpatrick, MS, MD (7-Synthes); Daniel V. Sheerin, MD (7-Synthes);
Thomas K. Wuest, MD (7-Synthes);
Slocum Center for Orthopedics, Eugene, Oregon, USA
Purpose: Despite the widespread use of the dynamic hip screw (DHS) for fixation of pertrochanteric hip fractures, failure by cutout of the lag screw from the femoral head remains common. The dynamic helical hip system (DHHS) implant replaces the lag screw with a spiral blade that shows greater resistance to cutout in biomechanical studies. To evaluate the clinical performance of the spiral blade relative to the DHS screw, we performed an IRB-approved randomized, prospective comparison of the DHHS and DHS implants in a community setting.
Methods: 51 consecutive patients were recruited into the trial. Inclusion criteria included patients over 50 years of age with AO/OTA 31A1 or 31A2 fractures admitted to either a Level 2 or Level 3 trauma center. Surgeries were performed by 1 of 15 participating community orthopaedic surgeons. The patients were randomized to either a DHHS or DHS implant. A standard postoperative protocol was used. Follow-up occurred at 2 weeks and 6 weeks and then at 6-week intervals until healing occurred. Primary outcome variables included collapse of the implant on the final AP radiographs, failure by cutout, and implant failure. Functional outcome parameters, including the Hardy pain score, Jensen functional index, and Short Form-36 (SF-36) scores, were collected.
Results: There were 24 patients in the DHS group and 27 in the DHHS group. There was no difference in age, gender, American Society of Anesthesiologists (ASA) score, or fracture classification between the 2 groups. There was no difference in the quality of reduction measured on the immediate postoperative radiographs (P = 0.28). The tip-apex distance was 18.6 mm in the DHHS group and 18.5 mm in the DHS group (P = 0.40). The DHHS group had an average collapse of 7.4 ± 5.4 mm, while the DHS group had an average collapse of 7.7 ± 4.5 mm. This result was not significant (P = 0.45). The DHHS group had 2 failures by central cutout of the blade through the femoral head without significant varus collapse or superior migration. One was revised to a DHS and healed, and the other was revised to a proximal femoral locking plate that also failed and eventually required revision to a total hip arthroplasty. Investigation of the implants after failure showed possible binding of the blade shaft in the barrel as a mechanism of failure in both cases. No DHS implants cut out in this series, although 1 patient was revised to a total hip arthroplasty for symptomatic segmental osteonecrosis. There was no significant difference between the groups in the postoperative Hardy pain index (P = 0.7), Jensen functional score (P = 0.3) or SF-36 (P = 0.1).
Conclusion and Significance: This study holds the advantage of being performed by surgeons in the community setting, making the results more applicable to community surgeons who perform the majority of hip fracture surgery. Unfortunately, both groups were small and the study lacked power to determine significant differences in collapse or functional outcome between the groups. The higher incidence of failure in the DHHS group is concerning, despite the low numbers. The implant manufacturer has modified the barrel design to avoid this potential problem. Fortunately, the mechanism of failure with central protrusion leaves adequate bone stock in the femoral head for attempts at revision fixation. This is in contrast to the DHS implant that fails with superior cutout, making primary revision more difficult.
• The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an “off label” use). ◆FDA information not available at time of printing. Δ OTA Grant