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KneeFurther Opinion

Injury to the proximal deep medial collateral ligament

A Narvani, T Mahmud, J Lavelle, A Williams

J Bone Joint Surg [Br] 2010;92-B:949-53.

 

This paper primarily describes a case series from a high volume specialist knee practice, surgical treatment (direct repair) of deep medial collateral ligament (MCL) injuries in high level athletes. It also indirectly touches on several other issues regarding this often missed injury.  Can the diagnosis of an isolated deep MCL injury be made purely on the basis of clinical examination? How does one differentiate between a possible medial meniscal tear or an MCL injury, in the case of no or minimal medial laxity? Is our current classification system for MCL injuries sufficient to describe individual disruptions of different layers of the medial ligamentous complex? Which method of non-operative treatment is to be considered for athletes in mild to moderate MCL injuries and when should conservative measures be abandoned?

The quality of the physical examination remains to be the most important factor in establishing the diagnosis of a deep MCL injury.  Subtle examination skills are required to judge the laxity (if present) and the quality of an endpoint in medial joint space opening. This only comes through practice and experience. The proximal attachment of the deep MCL can be fully torn without causing significant laxity in valgus testing – highlighting the deficiencies of current classification systems.

Isolated MCL injuries rarely cause a large effusion, and the site of associated swelling can be pathognomonic. As the deep MCL is directly attached to the medial meniscus, the associated medial tenderness can be misleading. Exact localisation of the painful area, proximal to the medial joint line and distal to the medial epicondyle, but not at the level of the joint, can be the only telling sign, uncovering the potential cause of disability. Finding this spot, the deep MCL sulcus, often showing thickened scar tissue, can help establishing the diagnosis, and perhaps help avoid unnecessary surgery. The current paper brings to attention the possible involvement of the saphenous nerve as a contributor to the localised symptoms.  

An MRI is unavoidable as the rate of associated injuries can be as high as 78 %.1 The scans rarely show significant meniscal pathology if the clinical examination was negative for it. There is a very high degree of agreement between the results of MR imaging and an instrumented stress testing in grading acute MCL injuries.2 To simulate the dynamic nature of knee movement, and thus physical activity, simultaneous physical examination and dynamic MR imaging with a two-dimensional fast low-angle shot sequence have been used to quantify laxity and perhaps provide more detailed information about the extent of a MCL injury. The feasibility and availability of such dynamic imaging in a general orthopaedic practice is currently questionable.3

Identifying the thickened scar tissue or demonstrating complete disruption of the deep MCL on the MRI scan surely requires the trained eye of an experienced musculoskeletal radiologist, and close cooperation between radiologist and orthopaedic surgeon.

The MCL remains the most frequently injured knee ligament. The anatomical and biomechanical knowledge of the medial ligamentous restraints continues to be explored, and the corresponding treatment modalities continue to evolve. The deep medial collateral, which is anatomically part of Layer III of the medial collateral complex is not only an important medial static stabiliser, but perhaps more importantly it functions as a rotational restraint. The strain in the MCL varies in location during movement, and is concentrated near the femoral insertion site during valgus stress.4 Not surprisingly the majority of the injuries deep MCL injuries occur in this region, 88% (30/34) in the largest reported series by Jones et al.5 Despite our increasing understanding of the medial structures, currently used clinical classification systems of MCL injuries, rely on the inevitably subjective measurement of medial joint space opening (either in ° or mm) during valgus testing in full extension and in 30° flexion. Neither system differentiates between injuries to specific anatomical structures. MRI classification1 can be useful in experienced hands, and can identify patients who have complete deep MCL tears (Grade III-MRI grading), who might have unfavourable results with conservative management. Whether or not, this MRI classification system corresponds with current clinical classification systems, remains to be seen.

As with several other orthopaedic conditions, the treatment of these injuries has shifted from essentially surgical management, to mostly non-operative treatment. Surgical intervention has been mainly reserved for multi-ligament instabilities and for chronic MCL deficiencies. Invariably patients with mild to moderate injuries to the medial restraints of their knee are treated with a combination of initial rest, elevation, cryotherapy, pain relief, physiotherapy (early range of motion exercises and strengthening) and possibly injections to the affected area with or without ultrasound-guidance. Injections usually mean a single shot of corticosteroid or sucrose, whilst platelet rich plasma could be an option for the future. Although corticosteroid is an ideal therapeutic agent in incomplete tears and sprains, it is difficult to imagine how it can help in the healing of complete disruptions. With a well structured rehabilitation regimen, most patients with grade I-II injuries should be back to their normal level of activity after four weeks.6 Although no hard evidence exists regarding what is an acceptable timeframe for expecting improvement with non-operative management, it is reasonable to state that if no improvement has happened in the first 12 weeks following injury, new treatment modalities should be sought, being especially for athletes.

An earlier switch to surgical management might be indicated if a clear gap is seen at the femoral attachment of the deep MCL on the MRI scan, as these usually heal with secondary repair and with increased levels of the weaker type III collagen. 

Despite the generally good results with non-operative management, recent literature suggests that this conservative approach to grade I-II MCL injuries might not always yield satisfactory results. Persistent symptoms that inhibit sporting activities, following such management have been described in the context of deep MCL injuries, despite a well structured rehabilitation programme.5 Some of these patients could benefit from surgical management of their deep MCL tears.

In summary the key message of this paper is to alert orthopaedic surgeons to be suspicious of an isolated deep MCL injury if the mechanism involves valgus stress and external rotation, and when physical examination does not show any significant laxity. The site of the medial tenderness is just below the epicondyle, but above the joint line. MRI shows characteristic findings confirming the diagnosis. Conservative treatment should always be tried initially, which can be supplemented with a single steroid injection if necessary. A small group of patients will not improve, and might require open surgery, with potentially excellent results.

Clearly further studies are needed to establish the true incidence of deep MCL injuries amongst the larger group of all MCL injuries, and to justify early surgical treatment in patients who are not high level athletes.

References

1. Fetto JF, Marshall JL. The natural history and diagnosis of anterior cruciate ligament insufficiency. Clin Orthop 1980;147:29-38.
2. Rasenberg EI, Lemmens JA, van Kampen A, Schoots F, Bloo HJ, Wagemakers HP, Blankevoort L. Grading medial collateral ligament injury: comparison of MR imaging and instrumented valgus-varus laxity test-device: a prospective double-blind patient study. Eur J Radiol 1995;21:18-24.
3. Studler U, White LM, Deslandes M, Geddes C, Sussman MS, Theodoropoulos J. Feasibility study of simultaneous physical examination and dynamic MR imaging of medial collateral ligament knee injuries in a 1.5-T large-bore magnet. Skeletal Radiol 2010 Feb 14. [Epub ahead of print]
4. Gardiner JC, Weiss JA, Rosenberg TD. Strain in the human medial collateral ligament during valgus loading of the knee. Clin Orthop 2001;391:266-74.
5. Jones L, Bismil Q, Alyas F, Connell D, Bell J. Persistent symptoms following non operative management in low grade MCL injury of the knee: the role of the deep MCL. Knee 2009;16:64-8.
6. Indelicato PA. Isolated medial collateral ligament injuries in the knee. J Am Acad Orthop Surg 1995;3:9-14.

 

Sisak K, Consultant Orthopaedic Surgeon

University of Szeged, Hungary

E-mail: sisakkrisztian@yahoo.com