Total knee arthroplasty is mostly done to relieve pain and disability from a severe and degenerated knee. Deformities in the coronal and sagittal plane could be corrected with the help of cuts made in tibia and femur during total knee replacement as well as with ligament release. However, large deformities in the lower extremity particularly in the diaphysis region need correction prior to the total knee replacement. It helps to limit the amount of bone that will be cut and helps the ligament release. Several extra articular and intra-articular methods for the correction of diaphyseal deformity have been described. We present the case of clamshell osteotomy for the correction of diaphyseal deformity in the tibia and a total knee replacement after the osteotomy site healed.
Clamshell osteotomy was first described by Russell et al. in 2009 to correct deformities in the long bone [
A 65-year-old male with a BMI of 42 and uncontrolled type II diabetes mellitus came to our clinic with a fracture on the left tibial shaft. He was treated conservatively for 20 years. Radiographs showed a malunited fracture on the middle third left tibia in 20-degrees varus, 15-degrees apex anterior angulation with a 1 cm anterior translation of distal segment, 20-degrees internal rotation and 1.5 cm shortening. He also had severe tricompartmental osteoarthritis on the left knee (Figures
(a) Leg length view showing 30 degrees varus of tibia and several osteoarthritis left knee. (b) Lateral view showing 20 degrees apex anterior angulation at malunited fracture site.
CT scan—malunited fracture of the middle third left tibia.
Clamshell osteotomy was performed as described by Russell et al. [
(a, b) Internal fixation after clamshell osteotomy. (b) Blocking screw was used in distal tibia for proper positioning of rod which helped correction of deformity.
There are several studies which have concluded that calcium and vitamin D levels affect healing of the fracture [
(a–d) Postoperatively showing good healing at fracture site at 6 months.
Plan was made for extramedullary referencing for both tibia and femur. Custom-made cutting blocks were prepared prior to the surgery (Zimmer Biomet, Signature system; Warsaw, IN, USA) based on CT scan. The femoral valgus angle was set to 4.5 degrees and tibial varus-valgus angle was set to 0 degrees. The posterior slope on tibia was set to 3 degrees and tibial resection below lateral low point was 8 mm while below medial low point was 2 mm.
During surgery, two proximal screws from tibia nail were taken out using a fluoroscope. Plan was made for removal of the tibial nail if needed. A medial knee parapatellar approach for total knee replacement was made and distal femur and tibia cuts were made using custom made jig (Zimmer Biomet Signature). Distal femur, patella, and proximal tibial preparation was done. There was no interference of nail during tibial canal reaming and impaction of wings of tibial component. Remaining surgery was performed in routine manner.
Postoperative X-rays showed good alignment (Figure
Total knee replacement after removing proximal tibial nail screws. Removal of IM nail was not indicated.
Clamshell osteotomy reported by Russell et al. [
Deformities in tibia which included varus, anterior angulation, translation, rotation, and shortening were corrected using this technique. The placement of blocking screw lateral to the nail helped in preventing distal fragment going into varus. Russell et al. [
Fracture malunion, previous failed osteotomies, epiphyseal injury, osteomyelitis, metabolic bone disease involving bone, and Paget’s disease are the major causes for extra articular deformity in long bones. Deformities are considered extra-articular in the knee joint when proximal to femoral epicondyles or distal to the tip of fibula [
Sabharwal et al. [
Rajgopal et al. have reported correction of extra-articular deformity of 18 degrees in coronal plane and 15 degrees in sagittal plane for femur and 24 degrees in coronal plane in tibia with intra-articular resection [
The use of intramedullary guide for wedge resection of tibia was not possible due to presence of nail. The patient had long-standing rotational malalignment and previous surgery in tibia. This increased chances of rotational malalignment using extramedullary tibial guide. MRI-guided custom jig preparation was not possible due to presence of hardware around the knee. So we got CT-guided custom jig prepared for total knee replacement.
Clamshell osteotomy is an excellent procedure to correct an extramedullary deformity in the tibia in coronal, sagittal, and rotational plane prior to total knee arthroplasty. It reduces the amount of deformity correction needed during total knee arthroplasty. Tibial nail does not require removal and TKA can be done as soon as we can see clinical and radiologic evidence of healing at osteotomy site with early return of patient to normal activities of daily living.
The authors declare that there is no conflict of interest regarding the publication of this paper.