Minimally Invasive Osteosynthesis of Intraarticular Calcaneus Fracture Augmented by Femoral Head Allograft: A Retrospective Study

Aim: The aim of this retrospective study is to report the results of minimally invasive osteosynthesis when used for the treatment of intraarticular calcaneus fracture. This old technique is regaining popularity recently with the multiple advances added by different institutes when it is used in the management of intraarticular calcaneus fracture. Methods: Twenty-four patients who suffered from intraarticular calcaneus fractures between 2014 and 2019 were included. Twelve of them had Sanders II fractures (group A) and 12 had Sanders III + IV fractures (group B). The mean follow-up duration was 37.5 months. The mean age at presentation was 54.23 ± 12.48 years. The skin condition at presentation was poor (blood-filled blisters) in 25% of patients equally distributed between the two groups. The mean time to surgery was 5.6 days where patients with poor skin conditions were treated lately. The technique involved percutaneous ascending proximal-to-distal pinning of the calcaneus after reduction using a 2 cm mini-incision below the lateral malleolus and augmenting the fixation with femoral head cancellous allograft. The primary outcomes variables analyzed in this study are post-operative Bohler angle, post-operative Gissane angle, American Orthopedic Foot and Ankle Society (AOFAS) ankle/hindfoot score at long-term follow-up (Excellent>95, Good 75-94, Fair 51-74, poor 0-50), and the delta angle benefit score. The secondary outcomes included post-operative complications such as infection and osteoarthritis. Results: The radiological results showed significant improvement of Bohler angle from 6.09° ± 21.6 pre-operatively, to 31.79° ± 14.1 postoperatively with a p-value <0.001. An adequate reduction was achieved in 54.16% to 70.8% of patients. There is a trend to normalization of overcorrected fracture especially Sanders II with a mean reduction of 12,71° ± 11,88 at one year post-operatively (p=0.05). AOFAS score at the last follow-up shows 20.83% poor results (AOFAS<50), 50% fair results (AOFAS between 51-74), 16.67% good results (AOFAS 75-94), and 12.5% excellent results (AOFAS>95. The satisfaction rate was 83.3% (45.8% partially satisfied, and 37.5% fully satisfied). The incidence of superficial infection (wound inflammation and pin tract infection) was more prevalent in higher group B (40%) compared to group A (0%) with p=0.014. Other complications including osteoarthritis and varus deformity were found in 95.8% and 58.3% of patients respectively at three-year follow-up. Conclusion: The combination of minimally invasive osteosynthesis and femoral head allograft for the treatment of intraarticular calcaneus fractures seems to give fair to good functional results. Radiological data demonstrated that when the Bohler angle is over-reduced >40°, there was a tendency to autocorrection over time. This may be due to progressive depression of the angle over time as weight bearing is authorized; however, this must be analyzed carefully due to the low number of patients who were overreduced (seven patients). Our study demonstrates that this technique has a low early complication rate (especially low infection and soft tissue problems) but carries high long-term complications such as osteoarthritis and hindfoot varus.