Why did we undertake this study?
Hyperextension injuries are still a kind of black box in terms of structural damage they can cause to the knee joint. The spectrum of disease reaches from knee dislocations until more subtle, isolated knee ligament injuries. The latter, and particularly partial posterior cruciate ligament (PCL) injuries are extremely difficult to diagnose. Patients typically exhibit unspecific symptoms such as mild pain and swelling, and the use of MRI scans is limited in these injuries. Currently, no clear diagnostic strategy thus exists, which delays the treatment for these patients.
What is the specific question we wanted to answer?
We conducted this study to present a series of patients who experienced persistent and unresolved pain as well as an inability to resume physical activities following knee hyperextension trauma. All patients had undergone at least one previous knee MRI and many medical visits. In none of the patients could the cause of their problems be identified. We thus wanted to describe an uncommon triad of clinical signs observed in these patients.
What did we find?
All patients presented with a history of hyperextension trauma, associated with persistent pain, inability to resume physical activities, inconclusive MRIs and no findings at the standard clinical examination.
A closer clinical investigation of the knee near full extension did however reveal a triad of signs in all patients: a slightly increased hyperextension of the injured knee compared to the contralateral healthy knee and a posterior drawer (meaning posterior movement of the tibia in relation to the femur) as well as a step‐off between these 2 bones. Whereas these signs do classically increase when the knee is brought from extension into flexion in major injuries of the posterior cruciate ligament, they normalized in these series of patients.
The combination of patient history, clinical examination and additional investigations led to the conclusion that these results were consistent with a partial injury of the PCL, specifically affecting the smaller of its 2 bundles, i.e. the posteromedial bundle (PMB).
What are the implications of our findings?
To the authors' knowledge, isolated lesions of the PMB following knee hyperextension trauma had never been reported before. We hope that our findings will raise awareness in the medical community of these rare injuries of the knee, thus improving diagnosis and limiting the delay in treatment for these patients and we will work on further anatomical and biomechanical studies to further analyze this problem.
Authors:
- Caroline Mouton (CHL)
- Maximilano Ibañez (Hôpital universitaire Dexeus, Espagne)
- Felix Hoffmann (CHL)
- Joan Carles Monllau (Hôpital universitaire Dexeus, Espagne)
- Romain Seil (CHL)
More information:
https://esskajournals.onlinelibrary.wiley.com/doi/10.1002/jeo2.12052