Biomechanics and Physiology ( Rehabilitation of the anterior crugiate - Essay Example

 Introduction Rugby League can be considered as a ‘collision sport’ with a high risk of injury. According to statistics, the injury rates maybe as high as 1.4 serious injuries per game. The injuries occur not just during competition but also during training activities. (Sports Injury Bulletin, n.d). The most common injuries are strains, sprains and contusions. Injuries to the lower extremity are the most common with the medial collateral ligament sprain or tear being the most frequent lower extremity injury. Upper extremity injuries, especially to the shoulder, hand and fingers are also very common. Although less frequent, injuries to the head and neck are not unusual, the injury rates being between 11.8% and 81.1%. Gabbett TJ (2001) in his study to determine the severity and cost of injuries in amateur rugby league found that 58.8% sustained an injury that resulted in one or more missed games, 40.0% missed five or more training sessions, and 30% missed five or more games as a result of injuries. “The median time lost from employment or study for all injured players was 2 days per playing injury. A considerable proportion of injuries sustained in the present sample of amateur rugby league players were major, resulting in a loss of training, playing and employment or study time, and these injuries were associated with significant direct and indirect economic costs.” . However, only a small sample of players were used in this study, and further studies using a larger sample, would complement this study. Professional players sustain a higher proportion of recurrent injuries. The long term consequences of injury may include job limitations, reduced income earning potential, and increased personal medical costs. Detraining effects caused by injury Detraining can be considered as a partial or complete loss of training-induced adaptations, in response to an insufficient training stimulus. The detraining effects can be considered as short term and long-term consequences. The short-term effects include: a. Cardiorespiratory effects: Rapid decline in maximal oxygen uptake (VO2max) and blood volume. Due to the decreased stroke volume, the exercise heart rate increases insufficiently, and maximal cardiac output is thus reduced. b. Ventilatory efficiency and endurance performance maybe impaired. c. Metabolic: There is an increased reliance on carbohydrate metabolism during exercise d. Muscle: Capillary density and oxidative enzyme activities are reduced. Training-induced changes in fibre cross-sectional area are reversed, but strength performance declines are limited. e. Hormonal changes : Reduced insulin sensitivity, a possible increase in testosterone and growth hormone levels in strength athletes, and a reversal of short term training-induced adaptations in fluid-electrolyte regulating hormones. The long-term effects include: a. Marked decline in the VO2max and endurance performance. b. Increased carbohydrate utilisation and lowered lactate threshold. c. Muscle capillarisation, arterial-venous oxygen difference and oxidative enzyme activities decline. Oxidative fibre proportion is decreased. Force production declines slowly. The breakdown of proteins and deterioration of motor units causes a decrease in nerve impulses, reduced contraction rates and therefore, a decrease in the power capabilities of muscle contraction. “The negative effects of detraining can be avoided or limited by reduced training strategies, as long as training intensity is maintained and frequency reduced only moderately”. A marked reduction in the training volume maybe beneficial. Cross training may be effective to maintain training-induced adaptations. “Athletes should use similar-mode exercise, but moderately trained individuals could also benefit from dissimilar-mode cross-training”. In order to limit the detraining effects during periods of unilateral immobilisation, the existence of a cross-transfer effect between ipsilateral and contralateral limbs should be considered. Frequency and intensity of training after surgery Following ACL reconstruction, patients can expect to be using crutches with touch weight bearing for 1 week. The crutches can be discarded after 2-4 weeks, in a simple knee support. In this early period of rehabilitation, the emphasis is on control of swelling, flexibility of the joint, and return of strength. As the range of motion improves, the emphasis is more on recovering strength. Swimming and cycling are excellent methods of strengthening the muscles around the knee. Muscle strengthening is critical to recover muscle mass lost due to surgery, and to improve stability of the joint. The increase in muscle strength reduces stress on the joint ligaments. Activities like running can be resumed at about 2-4 months following surgery. More advanced strength and balancing or co-ordination exercises such as the wobble board, hopping and plyometrics, which strengthen the hamstrings and quadriceps muscles simultaneously, and gives the knee the strength to return to normal sport at about 8 months. Over 90% are able to resume their previous level of activity after ACL reconstruction. A small percentage of patients will be limited by persistent pain or instability Techniques used to rehabilitate the ACL ligament Following anterior-cruciate-ligament reconstruction, training programmes include exercises to strengthen the muscles around the knee, including the knee extensors. There are two types of programmes, the open-kinetic-chain exertions for the quadriceps and the closed-kinetic-chain activity. Either one of the two is prefered by trainers and physical therapists. The closed-kinetic-chain (CKC) exercise require the the foot to be fixed to a supporting surface (either stationary or moving), while open-kinetic-chain (OKC) movements allow the foot to be unattached to a supporting surface. The relative merits of OKC and CKC during post-ACL-reconstruction rehabilitation has been a subject of debate. Proponents of OKC exercises believe that they isolate the knee extensors the best and may produce maximum gain in knee-extensor strength, while proponents of CKC exercises feel that CKC exercises require simultaneous muscle activation across multiple joints, thereby stimulating greater functional improvement in the extensors and entire leg, compared with OKC. For both exercises “the muscle and resistance torque difference should be small, and thus the training stimulus should be maximal, as the knee moves toward full extension.” At present, it appears that both CKC and OKC training may produce equivalent gains in knee-extensor strength, between two and six weeks after ACL reconstruction, at least when strength is measured isokinetically New techniques and methods in rehabilitation Smart portable rehabilitation devices Real time monitoring of the patient's motions and forces and the ability for real time adjustments of the applied forces and motions is not possible with the majority of current portable orthotic devices and rehabilitative braces. A second class of devices with "active" or powered devices, which usually employs some type of actuator(s)and are definitely more versatile. Dynamic joint control training Ihara H, Nakayama A, 1986, in their study introduced dynamic joint control training and assessed its effects in improving neuromuscular coordination of injured knees using the Kin-Com Isokinetic Dynamometer. They concluded that simple muscle training does not increase the speed of muscular reaction but dynamic joint control training can shorten the time lag of muscular reaction. Aerobic water exercise This can include running, jogging and walking underwater in a pool. A typical water aerobic routine or workout lasts about 45 minutes and involves warm-up, cool-down and stretching exercises. The advantages of aerobic water exercise are: 1. The buoyancy offered by the water causes less strain on the joints and muscles. 2. The exercise routine can be adjusted to suit individual needs, restrictions and fitness levels. 3. It offers resistance in all directions, which is an excellent rehabilitating exercise as opposed to land exercises where work is done against gravity. 3. Water offers a natural resistance, which leads to better muscular endurance and tone. 4. Specialised equipment is not needed. 5. Compared to activities like cycling and running, the heart rate is maintained at a lower rate. However, although exercise in water may not be as effective as exercise on land for regaining maximum muscle performance, “rehabilitation in water may minimize the amount of joint effusion and lead to greater self-reports of functional improvement in subjects with intra-articular ACL reconstructions” Changes in dynamics/kinematics of the knee movement after knee injury The ACL has complex biomechanical functions. Other than providing mechanical stability and proprioceptive feedback to the knee, it also has a stabilizing role. The four main functions are, restraining the anterior translation of the tibia, preventing hyperextension of the knee, acting as a secondary stabilizer to valgus stress, reinforcing the medial collateral ligament, and controlling rotation of the tibia on the femur in femoral extensions of 0-30°. Any defect in this critical function can affect movements such a sidestepping and pivoting. ACL deficiency causes subluxation of the tibia on the femur. “With each episode of ACL instability, there is subluxation of the tibia on the femur, causing stretching of the enveloping capsular ligaments and abnormal shear forces on the menisci and on the articular cartilage”. In the long-term, an ACL deficient knee can develop significant osteoarthrosis The use of force plates during the rehabilitation programme Most force plates are designed into foot tracks and contain piezoelectric force sensors with quartz crystals that convert force into data signal. Graduated force patterns visually represent the physical condition, and the impressions are captured for gait in motion analysis and to monitor improvement. However, “standard gait analysis techniques can be cumbersome and time consuming. Subjects must walk at a set speed, place their feet squarely on one or more force plates, and data normally cannot be collected for successive strides. “Temporal, kinetic, and kinematic information collected during formal gait analyses can also be obtained from subjects walking on a motorized treadmill.” The advantage of this is the capacity to ensure a constant gait speed, and the ability to collect continuously. During rehabilitation, patients can receive continuous real-visual feedback. Knee braces According to the American Academy of Orthopaedic Surgeons, knee braces are of the following types: a. Prophylactic braces, which prevent or reduce the severity of knee injuries in contact sports. b. Functional knee braces, which provide stability for unstable knees and have been recommended following reconstructive surgery to reduce strain in an ACL graft. c. Rehabilitative braces designed to allow protected and controlled motion during the rehabilitation of injured knees. d. Patellofemoral braces, which are designed to improve patellar tracking and relieve anterior knee pain. There has been no study that has conclusively proved that post-operative knee braces help protect the healing graft after an ACL reconstruction. A knee brace cannot effectively stabilize a force that is high enough to disrupt an ACL reconstruction. However, there is really no harm in wearing a brace and if it makes the athlete more comfortable, wearing the brace does not affect the likelihood of re-injuring the ACL Motion capture/video in rehabilitation Human gait analysis helps in the correction of abnormal and inefficient gait in physical rehabilitation (Debrunner C, n.d). “Video capture virtual reality (VR) uses a video camera and software to track movement in a single plane. The user's image is thereby embedded within a simulated environment such that it is possible to interact with animated graphics in a completely natural manner.”. It has been applied in rehabilitation only in the past five years. Conclusion Postoperative rehabilitation is a major factor in the success of anterior cruciate ligament (ACL) reconstruction. In addition, biomechanical factors are also important from a prevention perspective. Biomechanical factors are modifiable and by modifying biomechanical factors, it may be possible to reduce the stress on the ACL. Ultimately, this may reduce the incidence of non-contact ACL injury and the associated long-term disability effects. Based on previous research, ACL stress may be reduced through reduced quadriceps activation, increased hamstrings activation, increased knee flexion, reduced knee valgus, and reduced tibial rotation. Functional knee braces provide a protective shielding effect on the ACL. Both CKC and OKC training may produce equivalent gains in knee-extensor strength. Read More