Abstract
Introduction
Fixed flexion isolated or along with varus / valgus is a common deformity for patients undergoing TKR. For a satisfactory outcome and normal gait post op FFD needs to be corrected completely. An additional distal femoral resection may be necessary to equalize the extension gape to correct Gr 2 FFDs.
Aim
To demonstrate full FFD correction without resecting extra distal Femur.
Methods
Prospective study between 2009–2012
Inclusion Criteria:
All cases of Gr2 FFDs
Exclusion Criteria:
Patients with h/o previous injury, fractures, surgery.
57 cases were recruited. All patients were implanted a PS knee. Measured resection technique was followed in all the cases.
In the surgical technique once distal femoral, proximal tibial and AP femoral cuts are made, additional distal femur is not resected. To equalize the extension gape posterior sharp condylar margin is resected. Posterior osteophytes are removed. Posterior recess is created by stripping the capsule off posterior surface of the femur and clearing off any loose bodies. If necessary a horizontal capsulotomy is performed at the level of Tibial resection. (video clipping)
Results
Pre op average KSS of 46 improved to 85 post op. 44 knees were Osteoarthritis and 13 were rheumatoid arthritis. 53 knees had complete correction intraop which was maintained post op. 4 knees had residual FFD of 5 to 10 degrees. 3 of them corrected in 3 months post op period. They had an extended rehabilitation programme.1 patient has persistent FFD 2 years post op.
Discussion
Patients undergoing FFD correction have a tighter extension gap The extension gap needs to be equalized to the flexion gap. This can be addressed either by resecting extra distal femur or by posterior soft tissue management. Resection of additional distal femur has an advantage of correcting larger deformity and is quicker as well.
However there is a clear disadvantage that there is loss of collateral ligament tension in flexion which leads to midflexion instability. Typically these patients feel unstable while descending stairs or getting up from chair unsupported. The joint line is raised causing Patella baja. This also can lead to restriction of ROMs post op.
The possibility exists of a mismatch between femur and Tibial implant sizes for that particular implant system. The more proximal the cut the chances of damage the collateral ligament attachment on Femur are more.
The method described above is more precise and avoids cutting extra distal Femur. Instead the emphasis is on the posterior structures. That avoids the collateral ligament imbalance in flexion. The flexion gap is better controlled while equalizing the extension gape hence Flexion – extension gap mismatch is avoided.
The 1 knee that did not correct completely was that of RA and persistent synovitis in the immediate postop period was perhaps responsible.
Conclusion
By a systematic approach to posterior release, Gr2 FFDs can be corrected without extra distal femoral resection. As shown in our study quite a few possible complications can be avoided by following the above mentioned algorithm.
