Deformed knees benefit from corrective soft tissue or bony procedures prior to TKR

Consider a sliding lateral femoral osteotomy for severe valgus, ligament releases for varus knees.

Issue: September 2007

The best way to approach total knee replacement in patients with severely deformed knees depends on whether the knee is extremely varus or valgus and the location of the deformity relative to joint articulation.

In cases of natural deformity, using careful ligamentous releases or osteotomies may be best, although a constrained total knee replacement (TKR) prosthesis and bone grafting might also be suitable, according to Douglas A. Dennis, MD, of Denver.

Posterior osteophytes are common. “These affect your balance in both the sagittal and coronal planes, and it is wise to try to remove these before you proceed with extensive soft tissue releases,” Dennis said at the 8th Annual Current Concepts in Joint Replacement Spring Meeting.

He provided tips for managing severe knee deformity prior to TKR such as doing releases in stages, especially in varus deformed knees.

Deformity causes

Douglas A. Dennis, MD
Douglas A. Dennis

Arthritis, previous osteotomy, fracture malunion, congenital deformities and some metabolic bone diseases can cause severe knee deformity.

“[It] is usually associated with malalignment and some degree of ligamentous imbalance, but also bone loss, stiffness … rotational deformities and excessive posterior osteophytes,” Dennis said.

He advised surgeons performing TKR under these circumstances to first determine if the deformity is intra- or extra-articular. “In general, intra-articular deformities require intra-articular correction,” he said.

Dennis corrects extra-articular deformity based on how extensive it is and location. For a deformity greater than 20° or in close proximity to the joint, he usually chooses an extra-articular osteotomy although he may occasionally opt for intra-articular correction with extensive soft tissue balancing.

Dennis also believes that extensive soft tissue releases, reduction tibial osteotomy or soft tissue advancement of the convex-side structures frequently seen in severe valgus deformities are most effective for intra-articular deformities.

Valgus vs. varus

When it comes to valgus and varus knees, approaches differ.

The hallmarks of a severely valgus knee include overly contracted ligaments and a severely contracted posterolateral capsule. For this kind of deformity, Dennis recommended sequential lateral releases of the posterolateral capsule (arcuate ligament) and “pie crusting” and stretching the IT band 1 cm to 2 cm above the tibial resection. In more severe cases, he suggested releasing other structures such as the lateral collateral ligament, popliteus tendon and rarely the biceps femoris and lateral head of the gastrocnemius which also may require the use of a constrained prosthesis. A sliding lateral femoral osteotomy is also used to correct severe valgus deformities and is valuable to correct lateral tightness in both flexion and extension since the lateral epicondylar fragment can be translated both distally and posteriorly.

Structures that could be released in varus knees vary by surgeon and may include the deep or superficial medial collateral ligament, posterior oblique ligament and semimembranosus insertion, as well as use of a medial tibial reduction osteotomy to reduce medial collateral ligament tension. Dennis said.

AP radiograph of patient's knee
The patient’s knee in this AP radiograph had severe varus deformity coupled with medial tibial bone loss, both of which needed to be managed prior to a total knee replacement (TKR).

Douglas A. Dennis, MD, indicates how severe the medial tibial bone defect is in his patient’s knee in this intraoperative photograph.

Autograft bone to manage patient’s defect
He used autograft bone to successfully manage the patient’s medial tibial defect prior to performing the TKR surgery. Intra-articular deformities are usually treated differently than extra-articular ones.

Images: Dennis DA

For more information:
Douglas A. Dennis, MD, can be reached at Colorado Joint Replacement, 2535 S. Downing St., Suite 100, Denver, CO 80210; 720-524-1367; e-mail: ddennis@coloradojoint.com . He indicated he has no financial conflicts to disclose.
Reference:
Dennis DA. Dealing with severe deformity: Bent but not broken. #41. Presented at the 8th Annual Current Concepts in Joint Replacement Spring 2007 Meeting. May 20-23, 2007. Las Vegas.