What did the study look at?
The lateral patellofemoral ligament (LPFL) resists inward displacement of the kneecap. The authors note that inward slipping of the kneecap is usually iatrogenic, meaning it results from medical treatment. The main causes listed are a previous lateral retinacular release (an operation to loosen the outer supporting tissue), an over-tightened medial patellofemoral ligament reconstruction, and detachment of the outer thigh muscle from the kneecap.
The aim of this article is to present a technique for treating chronic inward instability caused by a previous lateral release with a soft-tissue-only reconstruction using a widely available semitendinosus allograft (a hamstring tendon from a donor).
How was it done?
This is a surgical technique article, not a study measuring outcomes in a group of patients.
- A detailed history, examination, X-rays and magnetic resonance imaging (MRI) are recommended before surgery.
- The joint is first examined by arthroscopy (keyhole surgery), and any loose fragments are removed.
- Through an incision of about 4 cm along the outer edge of the kneecap, the ligament's natural attachment on the thigh bone is identified and a single suture anchor is placed there.
- A 22 cm semitendinosus allograft is folded in half and its midpoint is stitched to the anchor.
- The two limbs of the graft are passed between the layers of the outer supporting tissue, outside the joint capsule, looped around the tissue and fixed by stitching the graft to itself. No anchors, screws or bone tunnels are used in the kneecap.
- Tension is first set with a temporary stitch and checked while moving the knee.
The article also outlines the rehabilitation programme: for the first 2 weeks patients bear weight as tolerated with the brace locked at 0° and movement limited to 0-30°; this progresses to 0-60° by week 4 and 0-90° by week 6. Running and jumping exercises may begin between weeks 14 and 22 once a step-down test is satisfactory.
What did it find?
As a technique article, it presents no patient outcomes. The potential advantages described by the authors are:
- A theoretically lower risk of fracture, because no anchor is placed in the kneecap.
- Lower cost, as only one anchor is needed.
- Less disruption of surrounding tissue, because the direct attachments to the kneecap are left intact.
- A reduced risk of over-tensioning the graft, thanks to adjustment with a temporary stitch.
The authors' conclusion
The authors state that their technique recreates the lateral patellofemoral ligament anatomically and, in their view, offers several important advantages over previously published techniques. They also note that large prospective studies of outcomes after this operation are lacking.
Limitations
- The surgeon needs access to allograft tissue and advance planning.
- If associated cartilage problems are not addressed, progressive pain, loss of function and early osteoarthritis may develop.
- Assessment of the kneecap during surgery may not perfectly reflect its movement after surgery, which could result in a loose or over-tight reconstruction.
Reference
Kerzner B, Hevesi M, Fortier LM, Haynes MS, Gürsoy S, Dasari SP, Khan ZA, Yanke AB, Chahla J. Lateral Patellofemoral Ligament Reconstruction With Semitendinosus Allograft in the Setting of Previous Lateral Release. Arthroscopy Techniques. 2022;11(6):e1097-e1103. Licence: CC BY-NC-ND 4.0.
DOI: 10.1016/j.eats.2022.02.016
Free full text: PubMed Central (PMC9244735)
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.
