Aetiology of Overuse Injury
The most common injury for a runner is that of runners' knee which can also be known as iliotibial band friction syndrome. The knee is a complex joint and involves the tibia, femur and patella to work in unison. For many years the cause of runners' knee was thought to be caused by chondromalacia of the patella which is a softening of the cartilage of the knee cap; however it is also widely thought to be from the richly innervated subchondral bone, infrapatellar fat pad, or the medial and lateral retinaculum of the joint. However there is still confusion defining anterior knee pain with Witvrouw et al (2005) stating "there seems to be no clear consensus in the literature regarding the terminology for pain in the anterior aspect of the knee".
Mcginnis (1999) argued that ankle pronation and supination as well as knee flexion and extension should occur simultaneously to avoid placing the tibia in torsion and stressing the knee joint. Furthermore if overpronation occurs the unison of the ankle and knee may be disrupted and thus the coordination of the joint action is disrupted and abnormal stresses are imposed and muscle activity patterns will be altered. This in turn will cause a different line of pull on the patella tendon by misalignment of the femur and tibia altering the tracking of the patella within the femoral groove. This results in an abnormal stress pattern on the sides and the back of the patella causing injury to the patella or the femur, which is referred to as patellofemoral pain syndrome.
However, it is widely thought that another disorder called iliotibial band friction syndrome is more common within runners and is more appropriate to be called runners knee. Fredericson and Wolf (2005) state iliotibial band friction syndrome is the most common cause of lateral knee pain in runners, with 12% of all runners suffering from it at any time. Iliotibial band friction syndrome is a disorder commonly found in long distance and recreational runners. Fredericson and Wolf (2005) state "Iliotibial band syndrome is the most common cause of lateral knee pain in runners. It is an overuse injury that results from repetitive friction of the iliotibial band over the lateral femoral epicondyle" with pain occurring at around an angle of 30 degrees from straight and providing a snapping sensation as the inflamed part of the tract jumps over femoral epicondyle.
Iliotibial band friction syndrome can also be commonly found in other types of athletes such as cyclists, weight lifters and volleyball players as well as long distance and recreational runners'. Training related to this injury are thought to be such activities as running in same direction on a track, greater than normal weekly mileage, downhill running as well as running on a uneven surface. Fredericson and Wolf (2005) further argue that recent studies have demonstrated that weakness or inhibition of the lateral gluteal muscles is a causative factor in this injury. Fredericson and Wolf (2005) state when the gluteal muscles do not fire properly throughout the support phase of the running cycle, there is a decreased ability to stabilize the pelvis and eccentrically control femur abduction resulting in other muscles having to compensate leading to excessive soft tissue damage or tightness and myofascial restrictions contributing to iliotibial band friction syndrome.
The iliotibial tract is a strong band, extending down the outer side of the thigh to the top of the outer edge of the shin bone. Fredericson and Wolf (2005) state the iliotibial band is considered a continuation of the tendinous portion of the tensor fascia lata muscle, with some contribution from the gluteal muscle. It is connected to the linea aspera via the intramuscular septum until just proximal to the lateral epicondyle of the femur. The iliotibial band spans out and inserts on the lateral border of the patella, the lateral retinaculum, and Gerdy's tubercle of the tibia. However; Fairclough et al (2006) state "Iliotibial band syndrome overuse injuries may be more likely to be associated with fat compression beneath the tract, rather than with repetitive friction as the knee flexes and extends". A symptom related to iliotibial band friction syndrome is pain occurring to the lateral side of the knee which affects range of movement in the knee.
The pain may begin after the athlete has been running for a certain time or distance and increased to a point where running becomes impossible. Grisogono (1984) states that the pain usually occurs gradually with a slight ache being noticed at first, occurring at a particular moment within your activity such as 10 minutes running, and thus happens every time. The area will become inflamed and feel tender to touch and may radiate proximally or distally to the lateral side of the knee. An angle of 30 degrees is stated as a position where the athlete will become aware of the pain in the lateral side of the knee, with a snapping sensation as the inflamed part of the tract jumps over the prominent part of the edge of the thigh bone. Treatment for iliotibial band friction syndrome consists of such actions as modifying activities to avoid causing pain to the knee,these include not running down hill or running on uneven road surfaces.
When resuming a normal training regime applying heat to the area may be helpful as well as applying ice post activity to reduce swelling of the knee. Other methods maybe anti inflammatory medication to help prevent swelling to the area as well as complete rest, lateral wedge orthosis to correct any postural imbalance and finally a administered local steroid injection as a alternative option could be used. Hintermann and Nigg (1998) state 70% of runners with lower extremity injuries treated with orthotic devices will improve. Specific stretching techniques can be used as well to provide pain relief and help prevent future lateral knee problems. The use of knee strengthening exercises can also be used to strengthen the knee and prevent lateral knee pain.
If the lower limbs of the runner is not absorbing the shock correctly or efficiently as possible, it is likely that the runner's structure will become overloaded and thus the athlete will become tired and injury will occur. The most common biomechanical factor is pronation and this can lead to increased tension in the planter fascia and tibiallis posterior tendon, or possibly lead to posterolateral impingement of the peroneii tendons. Higher up the leg, excessive pronation will cause medial rotation of the tibia as previously stated and can effect patella tracking and can also increase tension in the iliotibial band thus causing iliotibial band friction syndrome. Hintermann and Nigg (1998) state that excessive pronation can be potentially harmful with compensatory pronation occurring due to anatomical reasons, however, not just the level of foot eversion but also the way the foot eversion is transferred into tibial rotation may be crucial to the overloading stress on the knee.
The overloading of the knee occurs within the running cycle with internal rotation of the tibia counteracting with the external rotation of the pelvis thus creating external rotation of the femur. Overuse injuries are more often caused by excessive loading rates to the specific area. Hintermann and Nigg (1998) argued that excessive pronation has been typically associated with the development of overuse injuries in locomotion, and that the transfer of foot eversion into the rotation of the tibia has most commonly been associated with the incidence of knee pain. McGinnis (1999) supports this and states pronation and supination also affect the magnitude of the stress imposed on the knee joint.
If the muscle group is stretched slowly then the loading rate is of a level which is comfortable, however if the muscle group is stretched quickly with a great amount of force then the risk of an overuse injury will be increased. A quick loading rate on a cold muscle group will produce a brittle response causing torn fibres and inflammation to the specific area thus causing iliotibial band friction syndrome. McGinnis (1999) states that the iliotibial band tendon consists of 70% water, 25% collagen and 5% elastin. Fredericson and Wolf (2005) further state that the fibres are tightly bound in a parallel arrangement along the functional axis of the tendon, this provides high tensile strength thought to be similar to soft steel.
An overuse injury to a runner's knee is caused by a constant repetitive loading to the knee joint. Tendons behave viscoelastically and exhibit adaptive responses to conditions of increased loading and disuse. Maganaris et al (2004) states most studies report that long term physical activity improves the tensile mechanical properties of tendons, yielding results opposite to those of disuse. It is further stated by Maganaris et al (2004) that hypertrophy may be partly accountable for these effects; however changes in young's modulus also indicate training induced changes in the tendon intrinsic material properties McGinnis (1999) states that running speed directly influences the size of the ground reaction force components with faster speeds being associated with higher loading rates.
The maximum vertical ground reaction force, for example increasing from approx two times body weight at a slow jog to six times body weight at a fast run. The higher forces associated with faster running speeds cause greater torques at the joints. Iliotibial band friction syndrome is a non traumatic overuse injury which is common in long distance runners. Hintermann and Nigg (1998) state that the factors most associated with running injuries such as iliotibial band friction syndrome include anatomical or biomechanical abnormalities. Further more Hintermann and Nigg (1988) state that poor alignment in the lower extremities and/or over pronation have frequently been associated with stress fractures of the lower limbs.
Hintermann and Nigg (1998) argue that excessive pronation determines the amount of compensatory internal tibia rotation, thus the greater it is the greater the potential of iliotibial band friction syndrome will have of occurring in the athlete. To lower the risk of iliotibial band friction syndrome the athlete should incorporate high levels of lower limb flexibility, strength training regime specific to the lower limb area as well as wearing the correct footwear and using orthotics if needed to correct any postural problems. Alternative methods of exercise such as swimming may be used to minimise risk of aggravating the tendon and thus not causing iliotibial band friction syndrome.
References
Bahr. R, Maehlum. S, Bolic. T. (2004).Clinical guide to sports injuries. Gazette Bok. 348-349.
Fredericson. M, Wolf. C. (2005). Iliotibial band syndrome in runners innovations in treatment. Journal of Sports Medicine. 35 (5). 451-459.
Grisogono, V. (1984). Sports Injuries - A self help guide. John Murray publishers ltd. 104-106.
Hintermann. B, Nigg. B.M. (1998). A Review: Pronation in runners implications for injury. Journal of Sports Medicine. 26 (3). 169-176.
Maganaris. C.N, Narici. M.V, Almekinders. L.C, Maffulli. N. (2004). A Review: Biomechanics and pathophysiology of overuse tendon injuries: ideas on insertional tendinopathy. Journal of Sports Medicine. 34 (14). 1005-1017.
McGinnis. P.M. (1999). Biomechanics of sport and exercise. Human Kinetics. 358-362.
Peterson. L, Renstrom. P. (2001). Sports injuries: their prevention and treatment. Taylor and Francis. 327-329.
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