1. GENERAL ASPECTS

Unless the knee dislocates tearing all ligaments, the most common combinations of ligament injuries involve the ACL together with either the MCL or LCL. Due to the severity of such injuries the capsular lining (SYNOVIUM) is invariable torn leading to excavation of blood into the surrounding soft tissues. It is therefore common not to find a significant knee effusion (HAEMARTHROSIS). In cases of severe swelling a proper clinical examination is often impossible to conduct and the blood accumulated in the joint may have to be aspirated first. After establishing a diagnosis a pressure bandage is applied and the patient treated with 'RICE'. Combined ligamentous disruptions are much more likely to require surgical repair/reconstruction than isolated injuries. Especially patients below the age of 60, who still maintain some sporting ambitions, are likely to experience signs of instability once recovered from the immediate trauma. Some might be able to compensate by using a stabilising brace, but if a patient develops symptoms during activities of daily living (ADL) one should not refrain from offering ligament reconstruction.

 

 

Post-operative radiographs of a 23 year old male patient who had injured his knee whilst skiing 3 weeks previously. When he fell he exposed his knee to a varus internal-rotation stress tearing LCL & ACL. The ACL was reconstructed using hamstrings taken from the same leg whilst the LCL was amenable to direct repair using two suture anchors. He was immobilised in a Plaster of Paris for two weeks and regained a full range of motion over the following 6 weeks. 

 

 

In those patients it is by no means always necessary to reconstruct all torn structures, as the replacement of one ligament might provide sufficient joint stability. The ACL should always be reconstructed first as it represents the major internal knee pivot. Residual laxity can then be assessed intra-operatively and if excessive, accessory structures will have to be reconstructed as well until satisfactory joint stability is achieved. Depending of the amount of surgery and the strength of the reconstruction or repair post-operative mobilisation has to be adjusted. In some cases a short period of immobilisation in a plaster or brace might be required, whilst in others early mobilisation is preferred.

 

 

Post-operative radiograph of a 49 year old male patient who had sustained a severe valgus external-rotation trauma to his left knee tearing both the ACL & MCL. The ACL was reconstructed using hamstrings taken from the same leg whilst the MCL was reefed and re-attached to the medial femoral epicondyle via suture anchors and screw. The leg was placed in a brace for 2 weeks, keeping his knee in 30° of fixed flexion to protect the MCL repair.  

 

 

2. POSTERO LATERAL CORNER INJURIES

 

Sometimes patients sustain an injury to a particular area around the knee, which clinician's describe as corner injuries. Most common are problems affecting the postero-lateral corner (PLCI), which hosts an array of different ligamentous constrains which may sustain a varying degree of damage. Broadly these structures include the lateral collateral ligament, the popliteus tendon, the posterior oblique ligament, and the posterior capsule.

 

Injuries to the postero-lateral-corner can be assessed with a variety of clinical tests. Foot external rotation at 30° and 90° should shows a side-to-side difference of at least 15° to establish an abnormality.

 

 

In severe injuries the posterior cruciate ligament may also be affected. Often such injuries are missed altogether especially if the mentioned soft tissue structures are stretched and attenuated rather than torn. However, the disability these injuries may cause the patient can be substantial. The clinician has to be aware of such problems which may only be apparent if a patient fails to fully recover after a single ligament repair or reconstruction and continues to experience signs of instability.

 

 

Coronal MRI sequence demonstrating an acute injury to structures of the postero-lateral corner, including the posterior capsule, popliteus tendon, posterior-oblique ligament and LCL (the latter is not seen on this sequence).

 

 

 

The treatment for PLCI is dependent on the experienced symptoms. However, in acute injuries the surgeon should try to repair the torn structures, as this is likely to provide the most satisfying results. If the diagnosis is delayed repair is usually unsuccessful. Ligament reconstruction, or advancement if the structures are stretched but not torn, may be an option but careful consideration should be given to the overall joint alignment. If there is any indication that the patient's knee has developed the slightest degree of a varus mal-alignment or if his gait presents a so-called lateral thrust, the surgeon should not proceed with soft-tissue procedure. In such unfavourable mechanical environment any ligament reconstruction or repair is likely to fail early, hence leg re-alignment may sometimes be the only sensible option to stabilise a patient with a chronic PLCI. This procedure is described in detail in the section SURGERY EXPLAINED. Very occasionally patients require both, ligament surgery and bony re-alignment. Such a decision, however, should primarily be based on the patient's symptoms.