Urho M. Kujala

Intrinsic Risk Factors and Athletic Injuries

SummaryThe benefits of physical activity are widely known. However, the risk of a musculoskeletal injury is an unfavourable consequence in physical training. Age, gender, injury history, body size, local anatomy and biomechanics, aerobic fitness, muscle strength, imbalance and tightness, ligamentous laxity, central motor control, psychological and psychosocial factors as well as general mental ability are factors in the predisposition to injury.Junior (15 to 16 years) and senior athletes seem to be at a higher risk of injury in many types of sport. However, the relationship between age and injuries apparently depends on both the type and intensity of activity practiced. The majority of injured athletes in many studies have been males. Men are, however, more likely to participate in vigorousexercise and sport and it is not known if men are at a generally higher risk of injury when the exposure is taken into account. Certain lesions, such as sprains, strains and dislocations, tend to recur. Previous injuries may necessarily not cause a repetition of injury if treated adequately, but certain individuals may be at a higher risk of injury due to injury-prone biological characteristics. Excessive height and weight have been shown to predispose to stress injuries in physical training. Idiopathic or acquired abnormalities in the anatomy or biomechanics in any joint may lead to a local injury. However, physical requirements vary widely between different types of activity and predisposition to injury due to anatomical or biomechanical factors seems to be characteristic for each type of exercise. Lack of fitness, muscle weakness, joint looseness and poor general flexibility have been suggested as factors in the outcome of athletic injuries but no definite conclusions can be made on the basis of the existing literature. Long simple reaction times to visual stimuli and long choice reaction times to visual stimuli have recently been related to musculoskeletal injuries. No exceptional personality dimension in injury proneness as a whole has been found and the results from specific groups cannot be extrapolated generally. Accumulation of life stress apparently predisposes to an athletic injury. Musculoskeletal injuries seem to be more common in subjects with lower scores in intelligence tests but no causation has been shown yet. Altogether, a complex network of risk factors for athletic injuries has been found. However, no prospective study including all the recognised injury risk factors has been presented in the literature. Further research is needed in the subject.It has been shown that injury rates in athletes can be decreased by modifying coaching and efforts to prevent injuries can therefore be recommended. Each type of activity has its characteristic injury profile and degree of risk and the type of injuries vary widely. Athletes, coaches and supervisors should be aware of the risk factors concerning the specific type of activity they are involved in. Anatomical considerations, motor performance requirements and psychological factors are particularly important. In addition major exposure to injury in a state of high life stress should be avoided in any type of physical activity. Athletes, coaches and supervisors should also be aware of the relevance of adequate treatment and rehabilitation after an injury to avoid recurrence of injuries.

Patellofemoral relationships in recurrent patellar dislocation

Magnetic resonance imaging was used to analyse the patellofemoral relationships during the first 30 degrees of knee flexion in women with recurrent patellar dislocation. The patellofemoral joints were imaged both sagittally and axially with the knee flexed 0 degrees, 10 degrees, 20 degrees, and 30 degrees. At the beginning of knee flexion the sulcus angle was greater than in unaffected women, the lateral patellofemoral angle was smaller, the patella displaced further laterally, tilted more laterally and the congruence angle was directed more laterally. At 30 degrees of knee flexion these differences were less marked than at 0 degree to 10 degrees. Logistic regression analysis showed that the sulcus angle at 10 degrees of knee flexion was the most diagnostic feature, indicating that there is an anatomical predisposition to recurrent dislocation and that pathological patellar tracking starts from the beginning of flexion. Traditional sunrise radiographic films taken at 25 degrees to 30 degrees knee flexion clearly miss diagnostically important information.

Disc degeneration in young gymnasts A magnetic resonance imaging study

Magnetic resonance imaging (MRI) was performed on 35 young competitive gymnasts and 10 control subjects in order to detect the number of degenerated discs and other lumbar spinal disorders. Lumbar radiographs were obtained from all gymnasts who showed evidence of disc abnormality on MRI. Eleven gymnasts had suf fered from episodes of low back pain during exercises and eight were found to have evidence of back trauma. Only 3 of the 35 gymnasts had MRI evidence of degen erated discs associated with Scheuermanns manifes tations and spondylolysis. Lumbar radiographs con firmed the diagnosis in these three cases. The results indicate that despite the excessive range of motion and strong axial loading of the lumbar spine that are asso ciated with gymnastic maneuvers, incurable primary damage to the intervertebral discs is uncommon in young gymnasts dunng growth.

GONADOTROPHIN‐RELEASING HORMONE AND HUMAN CHORIONIC GONADOTROPHIN TESTS REVEAL THAT BOTH HYPOTHALAMIC AND TESTICULAR ENDOCRINE FUNCTIONS ARE SUPPRESSED DURING ACUTE PROLONGED PHYSICAL EXERCISE

The mechanism of suppression of gonadotrophins and; testosterone during prolonged exercise was studied. Fourteen healthy males were injected immediately before an exhaustive bicycle run for 4 h, and; before a control period without exercise, with one of the following substances: (1) 1 ml of saline, (2) 100 μg of a GnRH agonist (buserelin), and; (3) 50 IU/kg of hCG. Each test was repeated for each subject 2 weeks apart, in a randomized single‐blind fashion. Blood samples were taken before the injections (sample A), 6 h after the injections (sample B), and; the following morning (sample C). During placebo treatment testosterone concentration decreased from A samples to B samples more in the exercise trial than in rest trial (31 vs 8%, P =0.02). This exercise‐associated decrease was reversed by both the GnRH agonist and; hCG treatments. Serum gonadotrophin concentrations responded identically to GnRH agonist injections during exercise and rest trials. hCG resulted in a greater increase of serum testosterone from A to C samples at rest than during the exercise trial (52 vs 33%, P=0.04). In conclusion, the exercise‐induced suppression of serum testosterone is associated with two effects: suppressed endogenous GnRH stimulation of gonadotrophin release during exercise, and decreased testicular capacity to secrete testosterone during recovery period.

Relationship between the pivot shift and the configuration of the lateral tibial plateau.

SummaryTwenty patients with a chronic anterior cruciate ligament tear were studied. First they were interviewed on the preoperative history of unexpected giving way (pivot shift), then they were tested for clinical pivot shift sign, and last, the configuration of the lateral tibial plateau was studied using magnetic resonance imaging. A connection could be noticed between the history of instability symptoms and the pivot shift sign at clinical examination (P < 0.001). Interestingly, there was also a link between the instability history and the configuration of the lateral tibial plateau (P = 0.0021), and, further, between the clinical pivot shift sign and the configuration of the lateral tibial plateau (P = 0.0002). The variation in the shape of the convexity of the lateral tibial plateau seems to be associated with the symptoms and prognosis of the patients with rupture of the anterior cruciate ligament.

Patellofemoral relationships and distal insertion of the vastus medialis muscle: A magnetic resonance imaging study in nonsymptomatic subjects and in patients with patellar dislocation

The correlation between the insertion level of the vastus medialis muscle and lateral patellofemoral angle (LPA), lateral patellar displacement (LPD) and tilt (LPT), and the height of the patella (LT/LP) was analyzed by magnetic resonance imaging (MRI) in patients with patellar dislocation (n = 10) and in control subjects (n = 10). Images were produced in 0 degrees and 20 degrees of knee flexion. The insertion level to the patella was also analyzed with the knee in extension. No significant correlation was noted between the insertion level and different patellofemoral indexes, but multiple-regression analysis showed that the best predictor for the insertion level was the LPA with the knee in extension. The insertion level was significantly more proximal in patients with patellar dislocations than in normal subjects.

The effect of volleyball playing on the knee extensor mechanism

The knee extensor mechanism was examined in 32 male competitive volleyball players (Group V) and in a control group of 49 young adult males (Group C) to evaluate the effects of previous jumping activity on the knee extensor mechanism. Several variables were re corded by means of a structured questionnaire, and by clinical and radiographic examination. The amount of physical activity from the age of 7 years onward was significantly greater in Group V than in Group C. The incidence of anterior knee pain during the year preceding the examination was higher in Group V (31%) than in Group C (6%;P < 0.01). The most common reason for anterior knee pain in Group V was so-called jumpers knee. No significant difference be tween the groups was found in the incidence of clinical symptoms and signs of patellar chondromalacia. There were radiologically detectable soft tissue calcifications at the upper or lower pole of the patella or anterior to the patella in 38% of the subjects in Group V, but no such calcifications were seen in Group C (P < 0.001). However, persistent symptoms did not correlate with the calcifications. Group V subjects had a slight but significant trend to patella alta when compared to Group C (P < 0.05) according to the Blackburne and Peel index.

Restoration of patellofemoral congruity by combined lateral release and tibial tuberosity transposition as assessed by MRI analysis

Twelve knees in eleven patients with subluxation or dislocation of the patella were assessed by MRI at 0, 10, 20 and 30 degrees of knee flexion, before and after vastus lateralis release and medial transplant of the tibial tuberosity. The preoperative position of the patella deviated the greatest from normal in 0–20 degrees of knee flexion. The operations were found to correct the lateral patellofemoral angle and the lateral patella tilt with or without quadriceps muscle contraction, but did not completely correct the marked preoperative lateral patellar displacement and tracking.RésuméDans 12 genoux présentant une subluxation ou une luxation de la rotule, la situation de celle-ci a été analysée en utilisant la technique de limagerie par résonance magnétique. Les images ont été réalisées, avant et après lopération, le genou à 0, 10, 20 et 30 degrés de flexion. La position préopératoire anormale de la rotule était parfaitement visible sue le genou étendu ou fléchi à 20°. La libération externe associée à la transposition de la tubérosité tibiale antérieure corrigeait cette déviation, surtout par rapport à langle fémoro-patellaire externe, avec et sans contraction du quadriceps. La correction du déplacement externe de la rotule nétait pas complète lorsque la déviation externe préopératoire était particulièrement importante.

Repair of the anterior cruciate ligament: Augmentation versus conventional suture of fresh rupture

A prospective case control study was made by comparing the results of a modified combination parapatellar tendon transposition repair of a fresh anterior cruciate ligament rupture with those of the conventional Palmer technique. The mean follow-up time was 4 (3-7) years. A tendency to better stability was shown by an objective clinical device. Subjective results concerning stability sensations of the knee were also better than those obtained by the conventional method.

Effect of patellar brace on patellofemoral relationships

The effect of patellar brace on patellofemoral relationships was analyzed using magnetic resonance imaging in 17 knees with patellar subluxation or dislocation. Images were produced in 0° and 20° knee flexions without the patellar brace, with patellar brace and with patellar brace after 1 h of walking. In knee extension, the patellar brace had an unfavorable effect on lateral patellar tilt, but decreased the tilt in 20° knee flexion. The excessive lateral patellar displacement was alleviated in both knee flexion angles. The corrected position was still apparent after physical exercise. Isometric quadriceps muscle contraction increased the displacement. These results suggest a positive stabilizing effect of the brace in patients with patellar instability.