Anterior Cruciate Ligament (ACL) Injury

Introduction

Knee injuries are very common in sports; understanding mechanism of injury is an important aspect for diagnosing and managing them effectively (Webb and Corry, 2000; Bahr and Krosshaug, 2005). While making a precise diagnosis, it is necessary to re-evaluate the knee at different stages since acute examination of injury is often difficult and might be inaccurate (Olsson et al., 2016). As MRI is used as a diagnostic tool for evaluation of knee injuries, its early use influences the clinical decision making in some cases where clinical evaluation defers (Cashman and Attariwala, 2014). Due to early use of radiological diagnosis, there are chances of neglect during subjective history and physical examination (Navali et al., 2013).

A case of 24-year-old kick-boxer with the history of a non-contact knee injury with minor complaints is an example of a difference in clinical findings and imaging. MRI on the same day of his injury revealed the diagnosis of ACL and medial meniscal injury. Unconvinced with advice for surgery, he visited physiotherapy clinic after 8 days. This essay is about the difference of opinion due to distinct findings in imaging compared to those in clinical assessment and subjective history. Reflective discussion about physiotherapy assessment influenced by early imaging of the mentioned case is the objective of this essay.

Patient History

A 24-year-old male patient had clicking sound, pain and swelling in his left knee on lateral and posterior parts while playing kickboxing. On 15^th February 2017, he was doing his regular practice in the morning following his warm-up. During mid-practice session, he rolled awkwardly on the heel and outside of his left foot with leg straight, and balanced himself on outside of his foot. He felt clicking with some pain on the lateral and posterior side of his left knee. He had a little discomfort while walking after the incidence, so stopped his session. Later in afternoon, he started experiencing more pain in muscles around the joint and deep at the back of his knee. He also had swelling around his kneecap, so he visited the orthopaedic surgeon in a nearby hospital. Surgeon referred him for MRI in the same hospital so he got it done on same day.

The surgeon also gave him pain medications and suggested a long knee brace to use. He collected his MRI reports next day and revisited the surgeon. His reports mentioned – grade 3 tear of anterior cruciate ligament (ACL), longitudinal tear at posterior horn of medial meniscus, grade 2 tear of posterior cruciate ligament (PCL). Therefore, the surgeon advised surgery to repair torn ACL and meniscus. Since he was not convinced thinking he had less severe symptoms, he did not go back to the surgeon and decided to go for a second opinion. When the patient asked for his case file, only written MRI reports were given back to the patient and MRI films were kept at the hospital. He continued medication and used long knee brace while doing the activity. 8 days after the incidence, he visited a private physiotherapy clinic on his friend’s suggestion and got re-assessed.

The patient had no previous history of injury in his knee joint. He is active and played kickboxing for past 7 years at an amateur level without any severe complaints in the same joint. He owns a security agency and is a portrait painter. His main complaints after the incidence were pain and weakness of the left knee joint.

Subjective examination

According to his description, mechanism of injury was varus force on his left knee due to body weight managed on lateral arch and heel of foot with knee extended. While starting a kick he lost his balance lifting his medial foot and managed himself on lateral arch and heel of his foot. He felt a click in the postero-lateral aspect of his knee and said there was no twisting of his knee since he was just starting to kick. When he felt the click, he had slight pain so he stopped the activity immediately and decided to go home. Since he was comfortable while walking, he went back home riding his scooter (5kms). He had done a proper warm-up before his training but skipped cooldown on the day of injury.

When he went back home, his pain gradually increased by the afternoon. He was walking inside his house without any problem. After the lunch, he was sitting relaxed on his bed with legs long and he started feeling more pain. He had difficulty moving his leg, so he decided to visit the nearest hospital. His sister helped him to get to the lift and then took him to the hospital by car. He was sitting with his legs long on the back seat.

He presented with complaints of weakness in the knee joint and superficial pain around the left knee joint particularly in lateral head of gastrocnemius, hamstring muscle tendons, patellar tendon and quadriceps (3/10). Although he was walking with pain deep within the joint (5/10), he had no complaints of instability or locking in the joint while doing any movement. The range of motion was full in the extension of the knee with slight pain around the patella, end range of flexion was painful roughly in popliteal fossa (also lateral knee) causing difficulty to squat. Mild localised swelling was present around patella (supra- and infra-patellar).

His pain increased with activity (never 10/10) and reduced significantly with rest. Within 8 days his pain reduced and he was more comfortable doing his household and self-care activities. Initially, he used to feel morning pain and stiffness when he was using a long knee brace at night. His pain and stiffness were less after 4 days when he started using it just for activities outside the home and stopped using it completely at night.

The patient stays in an apartment and his flat is on the fifth floor with the lift facility. He stays with his parents and sister. His family is very helpful to him. Except for his sister, everyone in the family is earning. He was very co-operative during his assessment. Because of his injury, he was not able to do social activities such as meeting his friends and could not attend his painting exhibition. He was able to manage his work from home. Although he was not irritable with his pain and condition, he was worried about the surgeon’s advice since he wanted to continue kickboxing.

Clinical Reasoning

Initial pain, swelling and stiffness suggested an inflammatory response to injury, which was subsided until the patient came to the clinic. Since MRI report did not mention joint effusion and considering the swelling was localised, the cause of swelling might be bursitis. The condition of the patient did not aggravate even though he reduced the use of the brace and during physiotherapy assessment, he presented with mild localised swelling. Thus, findings were suggesting the cause of swelling being peri-articular rather than intra-articular issue (Johnson, 2000; Frobell et al., 2007).

Mechanism of injury was suggestive of hyperextension on imbalanced foot with ‘pop’ felt suggested injury to ACL, but the patient never complained of instability even after reduced pain. Therefore, the severity of ACL injury considered amongst the diagnosis was not correlating with MRI findings, making it necessary to re-evaluate during the further objective examination (Frobell et al., 2007; Navali et al., 2013). In addition, the patient had no locking during flexion and extension of the affected knee but had pain at the end range of flexion. Longitudinal tear of medial meniscus present in the MRI report was considered the cause of deep pain during a deep squat. This suggested the need to assess medial meniscus (Osborne et al., 1995; Johnson, 2000; Navali et al., 2013; Cashman and Attariwala, 2014).

Previously obtained MRI reports and notes by the orthopaedic surgeon played a role while doing the initial diagnosis. A focus of the assessment completely relied on ensuring the extent of ligament injury since the clinical presentation was not matching MRI reports. Thus, the reasoning was highly influenced and non-analytical leading to pattern recognition (Norman and Eva, 2010). This caused neglect towards other components of subjective history; such as symptoms felt postero-lateral to joint, varus stress felt during the incidence, etc. PCL injury in MRI report considered less likely thinking non-contact hyperextension is a rare mechanism for PCL injury to occur (Logerstedt et al., 2011b).

Hyperextension of the knee joint with varus stress being one of the common mechanisms for PLC injuries requires a high level of suspicion to diagnose the condition (Chahla et al., 2016). Given the fact that in this case patient’s symptoms were allowed to subside before doing provocative tests, there was time for more analytical thinking for appropriate diagnosis (Norman and Eva, 2010). A broader cognitive approach of hypothetico-deductive reasoning should help for identification of information cues such as the mechanism of injury (Edwards et al., 2004). The more problem-solving approach towards patient’s complaints could help, assessing for his PCL and posterolateral corner (PLC) to address his present complaints (mentioned in conclusion part). Thus, diagnostic approach with the forward reasoning of patient’s complaints might have helped to reach a possible diagnosis of tibial rotational dysfunction (Elstein, 2000).

Objective examination

The patient is strong and athletic, 176cm tall and 79kgs. He did not complain of any neurological symptoms such as burning or tingling around the knee joint. On sensory examination, he had normal sensations on and around knee joint when compared to non-affected side. There was redness observable around the patella and when compared to the opposite side, the area was warm suggesting of inflammation. On palpation, he had pain in overall gastrocnemius muscle, hamstring muscle and tendon, quadriceps muscle and patellar tendon (near patella), near head of the fibula. These painful muscles were in spasm (3/10 on VAS). There was no significant pain on the medial joint line.

The patient was keeping his left knee slightly flexed while standing since he was taking less weight on the affected side. He has bilateral foot over-pronation. Left PSIS level was slightly lower than right. He was walking with antalgic gait, causing less stance phase on left leg and swing phase reduced with small cadence. Single leg standing with support was painful and the pain was mainly in surrounding muscles and around the patella. Supported squat gave him deep pain posterior and lateral to the joint along with superficial pain in muscles. Supported step-up and step-down was painful in similar areas mentioned above. During all these activities, he had no complaints other than pain, such as giving away feeling or locking in the joint. The patient was confident while doing all these activities and mentioned that the pain was tolerable. Functional tests apart from gait were performed after initial pain relief for 4 days.

Active and passive ranges of knee joint were full but end range flexion was slightly more painful during both (more in active); the pain was deep in the posterior and lateral joint. Throughout the ranges, he had complaints of mild superficial pain in surrounding muscles and around the patella. Resisted activity was weaker and painful compared to the unaffected side. On manual muscle testing, strength for flexion and extension of the left knee was 4/5 compared to 5/5 on right knee.

Repeated assessment along with the pain management for 4 days was done to ensure pain and spasm relief. Hinged-brace instead of long knee brace was suggested to him. After the considerable reduction in pain and spasm (1/10), his further assessments for provocative tests to differentiate ligament injury were done.

Anterior Cruciate Ligament

ACL injury was assessed using only anterior drawer test. Test position was in supine with knee flexed at 90ᵒ, foot placed on the couch and stabilised by the therapist. The anterior translation given with both the hands by the therapist was slightly more in the left knee than that in right when tested (Grade 1). Although the test was positive, the tibial translation was not conclusive of grade 3 tear of ACL. Positive anterior drawer test, MRI findings and trauma in hyperextension of knee suggested ACL sprain.

Medial Meniscus

Joint line tenderness was checked from the first assessment until pain and spasm were relieved. Joint line palpation always performed in the flexed knee. The patient had no pain on palpation on the medial joint line gave a negative test for medial meniscus injury. Apley’s test was performed at the later stage. Test position was in prone by stabilising distal thigh with one hand and other hand giving vertical pressure on patient’s heel. Therapist maintained patient’s knee in 90ᵒ of flexion throughout the test. Apley’s test was also negative for the medial meniscus.  Therefore, subjective history and clinical findings ruled out medial meniscal injury.

Discussion

Diagnosis of ACL injury confirmed after objective examination, but subjective history was still not clearly suggestive of it being an only diagnosis. Since the patient had come for the second opinion, his previous diagnosis by the orthopaedic surgeon and MRI reports affected the decision making process during the assessment. However, the literature suggests that accurate patient history and examination are necessary components for diagnosing ligamentous and meniscal injuries. It is also advised to use MRI to confirm the severity of the injury (Frobell et al., 2007; Navali et al., 2013). Patient history, in this case, is not suggestive of medial meniscal injury. Besides, it is also not suggestive of complete rupture of ACL without other severe findings in MRI, such as joint effusion/haemarthrosis (Frobell et al., 2007; Navali et al., 2013). Only the MRI report was given to the patient and not the film before leaving hospital created suspicion about the quality of MRI and disputable practice. Two news articles published in British Medical Journal, “India turns spotlight on kickbacks for referrals” and “We need to end “cut” practice in India” dated 27 August 2014 and 7 July 2017 respectively, highlight issues with referral practice and rationality of decision making.

Valgus load in a hyperextended knee, rotational force, instability and hemarthrosis are features of ACL complete rupture mentioned in literature were absent in this case (Bahr and Krosshaug, 2005; Frobell et al., 2007; Logerstedt et al., 2011b). Anterior drawer test performed for assessment is the less sensitive test in acute cases as a spasm of surrounding muscle might influence leading to false negative results. It is suggested to be used along with Lachman test since it has got a high diagnostic value for ACL injury assessment (Benjaminse et al., 2006). Pivot shift is another widely used test which is less specific and sensitive compared to Lachman test (Benjaminse et al., 2006; Leblanc et al., 2015).

Medial meniscal injuries are common with valgus and twisting force on knee joint, often presenting with a catch or lock with movement (Logerstedt et al., 2011a). But in this case mechanism of injury was varus, ruling out the medial meniscus as a possible diagnosis. Joint line tenderness has higher values of positive and negative likelihood ratios, which was negative. Although Thessaly’s and McMurray’s tests are better diagnostic tests compared to Appley’s test; a combination of history, pain location and joint line tenderness can also play important role in diagnosis (Logerstedt et al., 2011a; Smith et al., 2015; Décary et al., 2018).

Mechanism of injury, in this case, might have caused PLC injury which occurs less commonly (Crespo et al., 2015; Chahla et al., 2016). PLC injuries are associated with concomitant injuries of cruciate ligaments. Since MRI report was also showing PCL and ACL involvement, along with the subjective history and pain location, to suspect PLC injury (Logerstedt et al., 2011b; Crespo et al., 2015); evaluation of PCL and PLC during first assessment would have helped towards a possible diagnosis. Although there are fewer studies on diagnostic tests, available studies mention that frog-leg test and posterolateral tenderness are useful to diagnose PLC injury (Ellera Gomes, 2016; Ranawat et al., 2008). Also, there are limited studies evaluating the specificity of PCL tests; but the posterior drawer test, quadriceps activation test, posterior sag test have a better sensitivity (Kopkow et al., 2013).

No patient reported outcome taken in this case to address psychosocial aspects. Factors such as difficulties in performing social activities, the surgical advice might be important in acute conditions affecting lower limb. Lysholm score used in ACL and meniscal injuries is responsive in acute trauma and might be useful patient reported outcome for knee injuries (Briggs et al., 2006, 2009; Logerstedt et al., 2011b)

Conclusion

Imaging has to be used as supportive to clinical finding and its early use might affect the decision making process. Knowing the right cues of available information is important for accurate diagnosis. Therefore, patient history and clinical evaluation play a major role in diagnosis. The findings in the MRI report were not clinically matching. Hence, a more analytical approach would have helped in this case, as the quality of MRI was unknown and only written reports were available.

A cluster of diagnostic tests is useful while assessing particular injuries instead of using only one or two tests. Some of the tests alone might not be of diagnostic value but in combination with other tests might improve quality of assessment. Better tests such as Lachman test and pivot shift test could be of more diagnostic value in conjunction with anterior drawer test for confirming the extent of ACL injury.

The patient recently assessed by different physiotherapist had the complaints of postero-lateral instability. Although patient manifested with postero-lateral instability after 14 months of injury incidence, early symptoms were quite localised postero-lateral to joint. Further diagnosis of his recent complaints is unclear. Thorough knowledge of pathoanatomy and high suspicion is necessary to speculate PLC injuries. These injuries might present with injuries to other ligaments in acute phases. Since PLC and PCL injuries might not present with early instability, it might be misgiving. Patient’s symptoms subsided in a short period, had a huge impact in ruling out the possibility of a broader diagnosis. However, patient history was enough suggestive to carry out clinical examination for PLC and PCL.

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