Lateral knee injuries

Transcription

1 Created as a free resource by Clinical Edge Based on Physio Edge podcast episode 051 with Matt Konopinski Get your free trial of online Physio education at Orthopaedic timeframes Traditionally Orthopaedic Specialists advise a 12 week timeframe for return to sport with high grade injuries to the Lateral Collateral Ligament (LCL). However with a sound knowledge of the anatomy and biomechanics of this region these time frames can be challenged. The boundaries may be pushed with an accelerated rehabilitation programme and the athlete may return to sport at 6 weeks. Sources of lateral knee pain Lateral meniscus rarely seen acutely in isolation. Degenerative lateral meniscal pathology is common as the tibiofemoral surface on lateral side is not concave/convex but convex/convex. Also the surface area is smaller than the medial side so the forces are focus on a small surface area. Osteochondral defect - may be associated with meniscal injury. Pain is produced specifically when a defect affects the bone as the chondral surface is aneural and avascular Lateral collateral ligament Anterior cruciate ligament (ACL) rupture immediately after an ACL injury athletes will hold the lateral aspect of the knee Postero lateral corner anatomically the LCL encompasses the posterior lateral corner. This injury is uncommon in soccer

2 Mechanism of injury The mechanism of an LCL injury is forced external tibial rotation relative to the femur. This is normally in a fixed foot position, for example landing from a header and an extrinsic force from an opponent offsets the trunk and forces the tibia into external rotation. Injury can also occur when running where an extrinsic force from a tackle causes overpressure into external rotation. An LCL injury mechanism is different from ACL mechanism as there is no associated hip adduction and knee valgus with LCL injuries. The lack of knee valgus is why the lateral meniscus is not commonly associated with LCL injuries. If available it can be helpful to analyse the injury mechanism on video to inform the clinician of the potential structures involved. Subjective assessment Athletes often report vagueness with LCL injury. They often complain of lateral knee pain and find it difficulty to be specific about the distribution of symptoms. Reporting, It does not feel right. This may be accompanied with reports of instability and discomfort when kicking. It is important to determine if the athlete was able to continue playing after the injury. With LCL injuries athletes are often able to keep playing despite sustaining a high-grade injury. This is due to the reinforcement from other structures in this region such as the Posterior Lateral Capsule, ACL and Popliteus. Athletes with lateral meniscus pathology are more specific about symptoms around the joint line and in acute injury are unable to continue playing. It is difficult to differentiate between osteochrondal defects and Meniscal pathology. If the athlete has had previous partial Lateral Meniscal resection then this predisposes them to chondral pathology. Ask the athlete if they feel like the symptoms are superficial or deep. If they report it is superficial this may inform the clinician of an extra capsular LCL injury rather than a deep intra capsular Meniscal pathology. 2

3 Red Flags The degree of discomfort associated with the injury is important to consider in the athletic population. If they are unable to walk off the pitch then suspect a significant ligament (ACL) or bony injury. In this situation it may be appropriate to immobilise the athlete and stretcher them off the pitch. Objective Assessment Sweep test for joint effusion LCL injuries present with a lack of swelling initially. The athlete could have a complete rupture of the ligament with limited swelling on assessment. At 24 hours they may have extra capsular swelling presenting as fullness on the lateral side of the knee. The Lateral Meniscus is intra articular so would expect significant knee joint effusion with an injury to this structure. There may be a small amount of effusion in the knee with LCL injury however this will be subtle. Knee range of movement in the sagittal plane athletes with LCL injuries often have full range of movement with discomfort at end of range flexion. Palpate the region Put athlete into figure 4 position (cross one leg over the other) as this exposes the LCL. Palpate the LCL from origin which is posterior and proximal to lateral femoral condyle all the way distally to the Fibular attachment. If the source of pain is palpable then suspect LCL injury. When palpating feel for ligament continuality and if the ligament feels taught. After LCL injury the ligament may not have the same taught band feel as the opposite leg. Modified Thessaly test typically described at 20 degrees of knee flexion for Meniscal pathology. Cadaver studies have shown that varus rotation is greatest at 30 degrees of knee flexion. Also at this angle the external rotation of the Tibia is greatest. To perform the athlete stands 3

4 on the injured leg holding onto the clinicians hands and then flexes the knee to 30 degrees. The athlete then rotates the body on the leg. Assess for pain and range of movement with this test, as an increase in range of movement would raise suspicion of LCL injury. Modified McMurray s test tests the lateral structures in non weight bearing position. This helps to differentiate between Meniscal and LCL pathology. If pain reproduced in weight bearing position then likely a Meniscal pathology where as if pain reproduce in non weight bearing position an LCL injury would be implicated. Range of movement in transverse plane Lay athlete prone and externally rotate the Tibia on the Femur. The dial test should be performed at 30 and 90 degrees of knee flexion. When performing the test at 30 degrees if there is excessive Tibial external rotation compared to the opposite side then an LCL pathology is indicated. Where as performing the test at 90 degrees assesses the Posterior Lateral Corner. Prone Varus Stress test Performed in prone instead of supine to increase the neural input of the LCL. Anecdotally testing in prone allows a better assessment of ligament stability. To perform the test place one hand on the medial side of the knee to stabilise and use the other hand to produce the varus force. External Tibia rotation can be added to further stress the lateral structures. The test should be performed at 0 degrees and 30 degrees of knee flexion, 30 degrees of knee flexion is often the position of most pain or instability. Anterior draw test and Posterior draw test if indicated to exclude other ligament pathology. Functional testing Depending on the objective findings and suspected grade of the injury it may be appropriate to ask the athlete to reproduce the injury mechanism. 4

5 Test retest Repeat the Prone Varus stress test and palpation in the figure 4 position to gain information about ligament healing during the rehabilitation process. Imaging Ultrasound is the imaging of choice with LCL injuries. Ultrasound is preferred as the athlete can be imaged dynamically. During imaging the prone Varus Stress test can be performed to give an indication of stability. Magnetic Resonance Imaging (MRI) is often used in the elite population to pick up any subtly that may not have been picked up in the subjective and objective assessments. The use of repeated MRI scans during rehabilitation is not recommended to guide return to sport. There is an increased fluid uptake in the ligament during healing so the MRI may give false positives for ligament damage. At 3-4 weeks post injury an MRI may be reported as 90% fibre damage however clinically the ligament can be palpated and the Varus Stress test is stable. MRI can cloud the judgement so it is important to use clinical assessment to guide the rehabilitation and return to sport. If re-imaging is required then Ultrasound should be used. Risk factors for injury Anecdotally, quadriceps weakness is a risk factor for injury. Quadriceps weakness predisposes the athlete to increased knee flexion on landing tasks. This places the knee into an at risk position for LCL injury and leads to increased trunk flexion which takes the centre of mass outside of the base of support. As a result the athlete is more likely to be offset from an external force. Athletes who are managing Patella Tendinopathy are reluctant to absorb force through the knee when landing and are predisposed to injury due to increased knee flexion. Athletes who are hypermobile have a greater risk of ligament rupture. 5

6 Athletes who are lateral foot loaders place more load through the lateral side of the knee predisposing to lateral knee injury. This is associated with high rigid arches, previous history of 5 th Metatarsal stress response or fracture, Tibia Varum and Femoral Anteversion. Management of LCL injury The athlete is braced for days or up to 21 days if significant instability on testing. Bracing aims to reduce the strain on the LCL and reduce any Tibial rotation. The brace should be set at 30 to 70 degrees of knee flexion. This places the ligament in a shortened position to allow for clot formation and bridging of tissue. The athlete should be non-weight bearing with crutches for the first 3-4 days to allow for the inflammatory and proliferative phases to start. If the brace is to be worn for 10 days, the first 4 days should be set at the initial range of movement and then gradually increased. The brace can be removed when the ligament can be palpated and it is assessed stable on Prone Varus Stress testing. Strength If possible strength work should start the day after the injury to avoid atrophy and Quadriceps inhibition. In a supervised rehabilitation setting the athlete can leave the crutches and weight bear through the injured leg. Early on in the rehabilitation the athlete should be able to get into the split squat position. This will allow the Quadriceps to be loaded encouraging ligament modification and increase in collagen content. A muscle stimulation device can be used during the split squats. If the unit is programmable then set to 3 seconds decline and 3 seconds incline phase with the frequency level at 75 Hz to facilitate maximal fast twitch muscle 6

7 contraction. During rehabilitation the athlete should be progressed through sagittal movements before introducing movements in the transverse plane. Hamstring Exercises The LCL has a shared attachment with the distal long head of Biceps Femoris muscle. Knee dominant hamstring exercises should be avoided in the first 2-3 weeks to avoid pain and allow the ligament to adapt. Hip dominant hamstring exercise may be used in the first 2 weeks. A paper by Bourne (2016) looked at the hamstring activation of different exercises and showed that knee dominant exercises increased EMG activation more than hip dominant exercises. Cardiovascular Fitness Cardiovascular fitness should be maintained to facilitate a quick return to sport. Upper body only swimming in the pool with the brace on can be performed. As the range of movement of the knee increases a bike can be introduced along with aqua jogging. Language Reinforcing to the athlete how strong the lateral side of the knee is can assist in any feelings of instability. The fact the player was able to play on with the injury and they were not severely inhibited should also be used for reassurance. Where possible discuss previous good experiences of rehabilitating other athletes with the same injury. Use the experiences of other athletes that have returned to sport in a maximum of 6 weeks and have developed no further problems after returning to training to reassure newly injured athletes. 7

8 Free sports injury assessment & treatment videos As mentioned in this episode Matt is presenting a video on Accelerated rehabilitation of LCL injuries, which you can get free access to at /matt The free videos available for a short time include: Shoulder and AC Joint injury with Dr Rod Whiteley Shoulder injury and dislocation management with Adam Meakins Hamstring injury screening with Nicol van Dyk Lateral knee injuries with Matt Konopinski ACL injuries with Dr Enda King Sports Injury Virtual Conference Matt Konopinski will also be presenting at the Sports Injury Virtual Conference hosted by Clinical Edge along with the world leaders in sports injury management. His presentations will discuss: The anatomical and biomechanical principles associated with LCL injury The relationship of this to an accelerated rehabilitation programme MRI imaging Injury mechanism with the aid of video Injury classification Clinical assessment The rehabilitation form early to late phases Pitch based rehabilitation principles Find out more information on the Sports Injuries virtual conference and the free Sports injury assessment and treatment videos at 8