Arthroplasty in the Valgus Knee: Comparison and Discussion of Lateral vs Medial Parapatellar Approaches and Implant Selection

Abstract

Constrained implants are frequently used for primary total knee arthroplasty (TKA) in patients with moderate and severe genu-valgum (>10˚). This deformity presents corrective challenges for ligament release. The lateral-parapatellar approach has been advocated as an alternative to the traditional medial-parapatellar approach. Claimed advantages include better access for release of tight ligamentous structures, without requirement for release of the medial-collateral ligament.We present our comparative experience of the use of an unconstrained knee-replacement prosthesis inserted by the lateral-parapatellar approach in comparison to a constrained-knee prosthesis inserted via the medial-parapatellar approach.49 primary total knee-replacements in 48 (6 males, 42 females) patients were performed; 32 through a lateral-parapatellar approach (group L) using an unconstrained-prosthesis and 17 through a medial-parapatellar approach more often requiring a constrained-prosthesis (group M). Mean preoperative valgus angle was 18.5 (range 11-34˚). Patient demographics (p=0.7) and valgus correctability were similar between the two groups.There was no significant difference in the mean post-operative valgus angle. This was 4.2˚ (range 1-9.5˚) using the lateral-parapatellar approach and 5.3˚ (range 0.3-10˚), p=0.12, using the medial-parapatellar approach.Transient common peroneal injury occurred in 2 patients, both group L, in the presence of valgus angles of greater than 20˚. To date no joints have been revised, or are unstable.The use of a lateral-parapatellar approach, appropriate soft tissue release, and an unconstrained PCL-preserving implant, yielded in all cases a stable, well aligned knee arthroplasty. This represents a viable alternative to the constrained-prosthesis using a medial-parapatellar approach in patients with moderate and severe genu-valgum.

Keblish's lateral surgical approach enhances patellar tilt in valgus knee arthroplasty

“…The literature shows similar results between the two techniques in relation to the post-operative alignment in the coronal plane 17, 21, 22. Some studies point to a better postoperative range of motion using the lateral approach 21, 23.…”

“…Some studies point to a better postoperative range of motion using the lateral approach 21, 23. Another advantage is the possibility of using common implants (non-constricted), while the knee valgus operated using medial access route tends to more often require implants with larger constriction 22 . Furthermore, a major advantage of the lateral approach over the medial is to avoid opening both retinacula of the patella, since many cases of valgus knee require release of the lateral retinaculum to correct the course of the patella.…”

Lateral or medial approach for valgus knee in total knee arthroplasty - which one is better? A systematic review

“…This might provide an explanation for why the results of valgus knee replacement seemed to be more disappointing when a medial approach was used. 2 Therefore, a lateral approach might be favored in correcting the moderate to severe valgus knee for several reasons: 1,17,18,23 1) It is necessary in valgus knees to perform a lateral release, particularly for patients who have already undergone medial arthrotomy, to maintain the patella’s blood supply; 2) the lateral approach can facilitate the release of the lateral contracted element for a better view; 3) the lateral approach combined with tibial tubercle osteotomy (TTO) can improve patellar tracking. Burki et al.…”

“…8 Consequently, the surgeon must confidently achieve soft-tissue balancing, resulting in better load distribution and enhancing longevity and component stability. 32 Valgus knees operated on using a medial access route tend to require implants with greater constriction, 23 but authors from this article used different implants as well as different approaches, so direct comparison may not be possible.…”

Total knee arthroplasty for a valgus deformity angle of >90°

“…[14] Constrained implants are frequently used for primary TKA in patients with moderate and severe genu valgum (>10°). [15] Constrained TKA is commonly performed to stabilize the joint and correct the bone axis in patients with severe ligamental instability, gross deformity, bone loss, and extreme deviation of the straight leg axis. In the present case, a rotating hinge knee prosthesis was selected.…”