Simultaneous Total Knee Arthroplasty and Management of Extraarticular Fractures and Deformities

Abstract

Simultaneous total knee arthroplasty and management of extraarticular deformities and fractures is difficult and challenging issue. Extra articular deformities defined as any deformity which extend beyond the caapsuloligamentous envelope of the knee joint. Extra articular deformity can occur secondary to varied causes such as: • Posttraumatic degenerative disease. • Fracture malunion. • Iatrogenic causes, such as overcorrection or undercorrection of previous high tibial or distal femoral osteotomies. • Metabolic diseases such as osteomalacia, or rickets, and Paget disease. • Stress fractures Stress fractures can be considered as one of the commenst causes of tibial extra articular deformities.

Stress fractures are observed in elderly patients, where normal stresses that are placed on abnormal bone result in fracture, it arises when repeated, cyclical, low magnitude forces exerting upon a weakened bone over a considerable period of time

This study looks at the reciprocal relationship between knee arthroplasty & a nearby tibial or femoral fracture or osteotomy. Simultaneous arthroplasty & fracture fixation or deformity correction is an attractive treatment strategy for these complex problems.

Results were assessed in the guidance of the Knee Society Scoring System. The average postoperative clinical knee score was 88.2 compared to an average preoperative score of 18.9. The average postoperative functional knee score was 72.7 compared to an average preoperative score of 12.3. The statistically significant improvement of postoperative pain scores, range of motion, stability, and limb alignment reflects success of simultaneous total knee arthroplasty and fixation of fractures or correction of the deformities. Complications included only one case who developed non union at the fracture site due to coupling failure between stem and femoral component, and this patient was treated with re fixation of the osteotomy site by long locked plate to maintain the overall alignment and thus was enough for stimulate healing at the osteotomy site, also there were five cases who developed wound problems and infection treated with serial debridment and close monitoring till cure, only two cases developed fracture after operation, one of them was fracture distal to press fit tibial stem and it was managed with bone graft, the other one was patient with stress fracture distal femur who had fracture at the tip of the femoral stem and managed conservatively. It was concluded that in coronal plain extraarticular deformities more than ten degrees, intra articular bone resection and soft tissue balancing alone will not be the best option, as, in such deformities ligamentous imbalance is strongly expected , so , simultaneous corrective osteotomy and total knee arthroplasty considered the best option , although there is expected difficulties such as length of the operation, infection, wound problems,and healing at fracture site , however , with proper precautions and anticipation of the expected problems , such technique will give excellent result. Also, simultaneous fixation of stress fractures in patients who have ipsilateral arthritic knee is strongly recommended, as correction of the overall mechanical axis will decrease stresses at the fracture site, and so, facilitate fracture union.

The benefits of these strategies are obvious ; beside its practicality, limiting the number of surgeries by performing three or four procedures in one setting (total knee replacement+osteotomy+internal fixation+bone graft),the financial & hospital burdens are reduced .The prosthesis & its stems add to fracture stability ,& an ample amount of autogenous bone graft is produced to accelerate bone healing.

Finally, a careful pre operative planning with determining the actual dimension of the problem beside selecting the proper technique will lead to achieving the best results.