Sports Injuries: Overuse PDF

Chapte r 5 And he's got the icepack on his groin there, so possi.bly 11 0t the old shoLdder injury. Ray French , British TV sports commentator Overuse injuries present three distinct challenges to Table 5.1 Overuse injuries: predisposing factors the clinician--...

Chapte r 5 And he's got the icepack on his groin there, so possi.bly 11 0t the old shoLdder injury. Ray French , British TV sports commentator Overuse injuries present three distinct challenges to Table 5.1 Overuse injuries: predisposing factors the clinician----ciiagnosis, understanding of why the Extrinsic factors Intrinsic factors injury occurred. and treatment. Diagnosis requires taking a comprehensive history of the onset, nature, Training errors MalaHgnment and site of the pain along with a thorough assess- excessive vol ume pes planus ment of potential risk factors; for example, train- excessive intensity pes cavus ing and technique. Careful examination may reveal rapid increase rearfoot varus which anatomical structure is affected. It is often sudden change in type tibia vara helpful to ask patients to perform the maneuver that excessive fatigue genu valgum produces their pain. inadequate recovery genu varum The skilled clinician must seek a cause for every faulty technique patella alta overuse injury. The cause may be quite evident, such Surfaces femora l neck as a sudden doubling of training quantity, poor foot- hard anteversion wear, or an obvious biom echanical abnormality, or soft tibial torsion m ay be more subt1e, such as running on a cambered cambered Leg length discrepancy surface, muscle imbalance, or leg length discrepancy. Shoes Muscle imbalance The causes of overuse injuries are usually divided inappropriate Muscle weakness into extrinsic facto rs such as training, surfaces, worn out Lack of flexibility shoes, equipment, and environmental conditions, or Equipment generalized muscle intrinsic factors such as age, gender, malalignment, inappropriate tightness leg length discrepancy, muscle imbalance, m uscle Environment al conditions focal areas of muscle weakness, lack of flexibility, and body compos ition. hot t hickening Possible factors in the development of overuse inju- cold restricted joint range of ries are shown in Tabl e 5.!. humid motion Treabnent of overuse injuries will usually require Psychological factors Sex, size, body co mposition addressing of the cause as well as specific additional Inadequate nutrition Other elements such as activity modification, specific exer- genetic factors cises to promote tissue repair, soft tissue massage, endocrine factors and pharmacologic agents where appropriate metabolic conditions (Chapler I)). Stress fractures account fo r 0.7% to 20% of all sports Bone stress medicine clinic injuries.' Track-and-field athletes Bone stress reactions, which can develop into stress have the highes t incidence of stress fractures com- fractures, are fati gue failure injuries of the bone. pared with other athletes.'-l There is a continuum of 25  Fundamental princ ip les bone response to stress that ranges from mild (bone includes the forces transferred from surrounding strain) to severe (stress fracture) (Fig. 5.1). The clini- muscle activity. High levels of bone stress, through cal features of bone strain, stress reaction, and stress an increase in activity, may lead to higher rates of fractures are summarized in Table 5.2. Different fa tigue damage where the remodeling response may sites of stress fractures are associated with particular not be able to cope. This then manifests clinically as sporting activities (Fig. 5.2). a bone stress injury. Overload stress can be applied to bone through Mechanism two mechanisms: In a normal environment, musculoskeletal integrity 1. the redistribution of impact forces reSUlting in is maintained by a balance of fatigue damage with increased stress at focal points in bone remodeling activity, stimulated by normal repetitive 2. the action of muscle pull across bone. low-intensity loading forces.! The rate of remod· eling responds to the loads through the bone, which Such overload leads to osteoclastic activity that sur· passes the rate of osteoblastic new bone formation. resulting in temporary weakening of bone. If physical activity is continued, trabecular microfracrures result and these cause early bone marrow edema seen on MRI scanning. In most cases, bone responds to these microfracrures by forming periosteal new bone for reinforcement. However, if the osteoclastic activity continues to exceed the rate of osteoblastic new bone formation, eventually a full cortical break occurs.2 A summary of the histological changes resulting from bone stress is displayed in Figure 5.} Risk factors CT, X-ray or MRI There has been considerable research investigating changes the association between bone stress injuries and Bone strain various risk factors (Table 5.3). Two important risk factors are (i) a rapid increase or change in the load Figure 5.1 The continuum of bone stress: from silent on the bone (rapid change in volume or intensity stress reaction through to stress fracture. Stress fracture of training), and (ii) an energy imbalance between is detected by changes on X-ray, CT scan or MRI calories expended and taken in. Energy imbalance Table 5.2 Continuum of bony changes with overuse Clinical features Bone stra in Stress reaction Stress fracture Local pain Nil Yes Yes Loca l tenderness Nil Yes Yes X-ray appearance Normal Normal Abnormal (periosteal reaction or cortical defect in cortical bone, sclerosis in trabecular bone) MRI appearance May show increased high Increased high signal Increased high Signal ± signal cortical defect Radioisotopic bone scan Increased uptake Increased uptake Increased uptake appearance CT scan appearance Normal Normal Features of stress fracture (as for X-ray) 26  Spo rt s i njurie s: ov e r us e Site of stre ss fracture Associated sport/activity ~./ Coracoid prOi:ess of scapula Tra pshooting ~q ~ Scapula Running with hand weights Humerus Throwing; racq uet sports 1st i Olet:ranon Throwing; pitching r- 5capu la Ulna Racquet sports (esp. ten nis); gymnastics; volleyball; swimming; softball; wheelchair sp orts Ribs." Ribs-2nd- lOth Throwing; pitching Rowing; kayaking f-rlbS , - ~ ~\ ~ Pars interarticularis Gymnastics; ballet; cricket fast bowling; volleyball; springboard diving Pubic ra mus' Distance running; ballet ".,IS I , I Femur- neck Distance running; jumping; ballet p,ble _