What did the study look at?
Injuries to the ligaments on the inner side of the knee are usually treated without surgery. However, when someone with a total knee replacement (total knee arthroplasty) injures both the medial collateral ligament and the posterior oblique ligament, the knee can open inwards under load, which is known as valgus instability. The authors describe these patients as a challenging group who often need surgery.
One option is to revise the replacement to a more constrained implant; another is to reconstruct the ligaments. This article describes how the second option is carried out.
How was it done?
This is a surgical technique article accompanied by a video. The authors describe the preoperative assessment, decision-making and the procedure on a left knee:
- Assessment: x-rays are used to look for loosening of the implant or a fracture around it; the knee is stress-tested inwards in full extension and at 30 degrees of bending.
- Decision: age, bone quality, activity level, other medical conditions and the functional limits of a constrained implant are considered.
- Graft: a donor Achilles tendon graft (allograft) is split and prepared for both ligaments.
- Procedure: the grafts are fixed in thigh-bone tunnels with screws and to the shin bone with anchors and, when suitable, a staple; the leftover graft is folded to make a double-stranded posterior oblique ligament.
After surgery, the patient bears weight as tolerated with crutches, wears a hinged brace locked straight and receives 4 weeks of clot prevention. The aim is 90 degrees of knee bending by 2 weeks; the brace is stopped at 6 weeks, and return to running or higher-level activity is expected at 24 weeks.
What did it find?
This is not an outcome study; it does not report patient numbers or success rates. The authors list pearls and pitfalls of the technique, for example using the semimembranosus attachment as a landmark for the ligament's shin-bone insertion, the risk of weak fixation in osteoporotic bone, and the need to keep the thigh-bone tunnels from meeting each other or touching the implant.
In discussing the literature, they note that complete medial collateral ligament injury during knee replacement has been reported in 0.8% to 2.7% of cases, and that constrained implants have drawbacks such as bone loss and wear.
The authors' conclusion
The authors consider this technique a viable option for young, active patients who hope to avoid the risks of revision replacement and to restore stability against inward opening of the knee. They stress that these patients have several treatment options and that shared decision-making centred on the patient's functional goals is needed.
Limitations
- Data on how long this reconstruction lasts in a knee with a replacement are limited.
- Joint replacement surgeons typically have less experience managing an additional posterior oblique ligament injury.
- Revision replacement may still be needed later because of accelerated wear, especially in chronic cases.
Reference
Kerzner B, Swindell HW, Terhune EB, Ramos P, Fortier LM, Dasari SP, Khan ZA, Gürsoy S, Cancienne J, Chahla J. (2022). Medial Collateral Ligament and Posterior Oblique Ligament Reconstruction for Valgus Instability After Total Knee Arthroplasty. Arthroscopy Techniques, 11(9), e1531-e1539. Licence: CC BY-NC-ND 4.0.
DOI: 10.1016/j.eats.2022.04.003
Free full text: PubMed Central (PMC9519797)
This article summarises a published scientific paper for general information; it does not replace an examination or a personal medical assessment. Please consult your doctor about your symptoms.
