Rehabilitation Concepts for Multiple Knee Ligament Injuries

Multiple knee ligament injuries represent a signi ﬁ cant traumatic event with an important functional prejudice which involves the injury of at least two of the four major ligaments of the knee. Management of such injury requires a thorough assessment and an interdisciplinary approach.The rehabilitation program will be constructed in accordance to the severity of the lesion and the patients expectations. The higher the goals and a more pronounced injury will results in a higher degree of involvement from the rehabilitation team. In case of cruciate ligament injury associated with a collateral ligament injury the rehabilitation program is based mostly on the same principles as for a cruciate ligament intervention, with the ﬁ rst phase of the rehabilitation protocol being governed by an early protection phase due to the fact that early weight-bearing is considered a risk for later instability of the knee and influence over the healing tissue, while the second phase of protocol is characterised by gait restoration and maintaning balance and coordination. Multiple ligament injuries often necessitate longer rehabilitation periods, regaining full activity level being estimated at around 1 year post surgery. The purpose of the paper is to analyse the optimal modality of constructing a rehabilitation program for multiple ligament injuries and whether a consensus regarding protocol and procedures can be obtained.

for the posterior cruciate ligament integrity are posterior drawer test, quadriceps active test or the posterior sag test. However, these evaluation tests remain subjective and are fundamented on the clinician's experience and interpretation 13,14 .
Although in most cases patients history and clinical examination can off er valuable information regarding ligament lesions, MRI investigation are necessary, and provide value especially when clinical diagnostic is diffi cult or uncertain, and off er evidence which further dictate the surgical or conservatory treatment. Possible complications of the surgical intervention may include tear or laxity of the graft, possible development of arthrofi brosis, hardware movement or deterioration 15,16 .
Nevertheless, even if surgical intervention is postponed, a rehabilitation program is necessary and should be team guided.Th e purpose of the paper is to analyse the optimal modality of constructing a rehabilitation program for multiple ligament injuries and whether a consensus regarding protocol and procedures can be obtained.

MATERIAL AND METHOD
We conducted a review of the literature using online databases PubMed, Embase, and Cochrane library by typing the following words: anterior cruciate ligament, ACL, posterior cruciate ligament, PCL, collateral medial ligament, rehabilitation, multiple ligament injury.

RESULTS AND DISCUSSIONS
Th e rehabilitation program will be constructed in accordance to the severity of the lesion and the patients expectations. Th e higher the goals and a more pronounced injury will results in a higher degree of involvement from the rehabilitation team. Setting realistic goals represents a fundamental part of the rehabilitation program, designing objective goals leading to better and specifi c outcomes, and will result in a higher patient satisfaction and an improved functional prognostic. Th e rehabilitation planning should also be measurable and time-related, in order to benefi t from a better patient adherence, and should take into account the patients fear of unpredictability. Th is is why a permanent dialog between the rehabilitation specialist, orthopaedic surgeon and patient is necessary for goal attainment 17,18 .
In case of cruciate ligament injury associated with a collateral ligament injury the rehabilitation program is based mostly on the same principles as for a cruciate ligament intervention. Th e fi rst phase of the reha-

BACKGROUND
Multiple knee ligament injuries represent a signifi cant traumatic event with an important functional prejudice which involves the injury of at least two of the four major ligaments of the knee. Management of such injury requires a thorough assessment and an interdisciplinary approach 1,2 . Th e anterior cruciate ligament lesions appear when high forces are applied especially in actions such as pivoting or jumping 3,4 . Th e medial collateral ligament represents one of the most important stabilizers of the knee, which has a major role in supporting the knee against valgus stress, and also translational and rotational movement of the tibia 5 . Injuries of the ligament result most frequently from sport activities, falls or accidents and make for aprox. 40% of knee lesions according to some statistics 6,7 . Th e lesion can occur as a single injury, but it can be produced in association with other ligaments. When multiple ligament injuries are produced, usually the medial collateral ligament is associated with the injury of the anterior cruciate ligament, while the lateral collateral ligament injuries can be developed in combination with lesions of the posterior cruciate ligament 8 . Also, severe tear of the collateral ligament can intensify the load on the anterior cruciate ligament with 30 degrees of fl exion according to some authors 9 . Mild lessions are often treated conservatory, with adapted rehabilitation programs, while more severe lesions require surgical treatment in order to improve functional outcome 10 .
Clinical examination represents an important stage in diagnosting ligament injuries, since the knee joint is more susceptible to injuries due to anatomical orientation and also due to its weight-bearing role. Examination must include the patient's history and clinical evaluation in order to not neglect any potential lesions, which otherwise overlooked could lead to a degenerative evolution of the knee because of the elevated shearing forces and high compression 11 . Multiple clinical tests are used in order to probe ligament integrity. Nonetheless, some authors have observed that the interpretation of these tests might be slightly inaccurate, because of the fact that there isn't a well established methodology, and also some studies have reported inconcludent fi gures regarding specifi city, sensitivity and likehood ratios 12  Th e fi rst phase of the postoperative rehabilitation protocol is again dominated by the protection of the reconstructed tissues. Pain management and swelling prevention need to be addressed with the appliance of cryotherapy and maintaining an elevation of the lower extremity. Ice and compression should be applied at least 3 times a day for 20 minutes in the fi rst postoperative weeks. Patient will only be allowed a toe-touch weight bearing in order to avoid loading on the operated knee. Also hip abduction and adduction sidelying are forbidden for 6 weeks in case of aff ected lateral or medial ligament. For patients with a reconstructed posterior cruciate ligament, active knee fl exion is not permitted in order to avoid hamstring tension fi reing 26,27 . Active assisted range of motion can be performed, but limited to 90 degrees of fl exion. Patelar mobilisation is recommanded in the fi rst days of the rehabilitation period. Knee extension must be emphasized in order to obtain proportionate extension to the non-operated leg. A continuous passive motion device can be applied in the fi rst postoperative days for promoting range of motion. Progression criteria to the next rehabilitation phase must include mild to no eff usion and minimal pain of the knee 28 .
Th e second phase of the rehabilitation program begins at 6 weeks post surgery and lasts until the end of the 12 week. Th is phase is primarly focused on increasing muscle strength and working on gait pattern in order to normalize gait. Balance exercises are gradually introduced and the patient will be headlined idea of ,,gait cycle'' in order to to better comprehend the mechanisms of walking 26,29 .
Knee symmetry for range of motion is expected to be obtained during this period. Soft tissue and patelar mobilisation are continued. Hip and core strenghtening are performed. Possibile muscle imbalances must be taken into account and corrected. Heel slides and wall slides are suggested. One of the principle precautions that needs to be taken into consideration is the appearence of arthrofi brosis in case the patient doesn't fully participate into the rehabilitation program. Once the patient has advanced to complete weight bearing, proprioception exercises are included. For patients who had a posterior ligament reconstruction, open chained exercises are forbidden for the fi rst 12 postoperative weeks 30,31 .
When the patient has reached and maintained 90 degrees of fl exion, two legged press can be performed. bilitation protocol is governed by an early protection phase. Weight bearing restrictions are maintained for the fi rst 6 weeks post surgery, with the patient is being recommanded to wear a brace locked in extension 19 . One of the fi rst objectives is quadriceps training, while teaching the patient to perform isometric pumps numerous times a day by using a towel placed under the leg. However, if the patient presents an evident quadriceps insuffi ciency, neuromuscular electrical stimulation can be added in order to increase muscle performance. Obtaining full knee extension is another objective of the fi rst rehabilitation phase. Th is can be done by educating the patient to roll a towel under the ankle in order to facilitate gravitational forces to put the knee in extension 20 .
Plantar fl exion exercises using a resistant band and straight leg raises can be added to the rehabilitation program in order to induce muscle strenghtening. A special attention needs to be put on the exercise of the hamstring muscles in order not to put too much pressure, in case the graft has been taken from that area 21 .
Phase two of the rehabilitation protocol is characterised by gait restoration, after the brace has been removed and the patient is able to realize a straight leg raise without hesitation. Advances in gait training will be done gradually, with fi rst removing one crutch, and maintaining walking with a single crutch or the use of a cane, and then progress towards independent walking when the patient demonstrates a pain free ambulation and gait, and also the ability to execute a straight leg test without a lag 22 . In this phase of rehabilitation, aquatic therapy can be added to the program and especially ambulation on a water trendmill if permitted. According to AAOS guidelines, when the patient is able to perform 85 degrees of fl exion, a 90mm stationary bycicle can be added, in order to promote range of motion, and then will advence to a normal bycicle of 170mm after achieving 115 degrees of fl exion 10,23 .
In case of multiple ligament lesions, the rehabilitation program requires a higher degree of participation from both the pacient and the rehabilitation specialist, and also requires an interdisciplinary comunication with the orthopaedic surgeon. Multiple ligament injuries often necessitate longer rehabilitation periods, regaining full activity level being estimated at around 1 year post surgery. In this type of traumatic patients, a preoperative rehabilitation program is imperative, in order to functionally assess the patient and set optimal rehabilitation goals. Th e most demanding task in the rehabilitation protocol is fi nding an equilibrium betwe-fact that it presents a relatively low incidence compared to single ligament injury, and therefor there isn't a suffi cient amount of data and high quality evidence on the subject. On the other hand, surgical treament has proven to have statistically better outcome compared to conservative treatment, but there is still a lack of consensus regarding surgical procedure and optimal timing of the operation. Early weight-bearing is considered a risk for later instability of the knee and infl uence over the healing tissue. On the other side, this results in the patient not loading a signifi cant amount of weight when given the indication of partial weight bearing as some studies have evidenced 37 . Controlled weight bearing results in better proprioception and favors correct muscle activity. Th e evolution of the rehabilitation program should be adapted in order to adress the operated structure that presents the slowest time period for healing or has higher chances of failing. Th is idea is empowered by biomechanical studies that have evidenced the need to restrain diff erent muscle activities in order to protect vulnerable tissues 38 .

CONCLUSIONS
Multiple knee ligament injuries require an elaborate rehabilitation program which must harmoniously approach early mobilisation, weight bearing, adequate planning, muscle strenghtening and protection of the surgically treated structures in order to obtain a full return to daily activities and more endevour sport activities. Preoperative councelling and rehabilitation need to be taken into consideration, for proper treatment from the onset of the injury. Patient adherence plays a crucial role in order to optimise long term goals. Once motor control in obtained, a crossover to single leg press can be produced. For patients with associated PCL injury, range of motion is limited to 60 degrees when working with a leg press. Stationary bicycle can be introduced in the rehab protocol at the moment when full range of motion has been obtained. After reaching 100 degrees of fl exion, forward step up exercises are introduced, while step down exercises are being executed after reaching 120 degrees of fl exion, using at the beggining a 4 inch /10 centimeters step. Progression is to be made to 6 inch/15 centimeters step when proper coordination is observed. Afterwards, an eliptical machine can be used 10,32 .

ABBREVIATIONS
Progression criteria to the next rehabilitation phase will be based on the patients capacity to maintain a normal gait on all surfaces, a full range of motion on the operated knee and the ability to demonstrate and adequate leg control. A relevant kinetotherapy exercise for progressing is the patients ability to perform a step up and down single leg test with a good control 33 .
In the third phase of the rehabilitation program squats can be introduced, with an initial limited range of 45 degrees and then increase as the patient progresses into the rehabilitation program. On a fi rst basis, wall squats are recommanded, and then advance to independent squats. Th e patient will continue to improve muscle strength and proprioception. Aquatic therapy can be introduced in this moment of the rehab period. Isolated hamstrings strenghtening exercises will also be associated. Patients will perform open chain kinetic exercises with progressive resistance. Balance training will advance to exercises on unstable surfaces 34 .
Final phase of the rehabilitation protocol starts at 20 weeks post surgery, and includes adding more demanding tasks and introducing sport related programs adapted to the patientţs individual functional level. It is the phase that includes running and plyometric exercises, agility drills and single leg squats. Return to sport activities must be made after a thorough evaluation of the knee regarding the possibility of reproducing all the involved sport movements without any signs of pain or infl ammation, and the patient is able to demonstrate knee symmetry and similar quadriceps and hamstring muscle force. However, return to sport percentage is lower than return to work percentage according to some authors 10,35,36 .
Nonetheless, there are still many controversies regarding rehabilitation programs following multiple ligament injuries. Th e main cause is determined by the