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Biomedical subjects

P Kannus

Publications and source records attributed to P Kannus.

At least 19 recordsLinked to original sources

Genetic factors and osteoporotic fractures in elderly people: prospective 25 year follow up of a nationwide cohort of elderly Finnish twins.

OBJECTIVE: To determine whether genetic factors partly explain variation in risk of osteoporotic fracture, the true end point of the osteoporosis problem. DESIGN: Prospective 25 year follow up of a nationwide cohort of elderly Finnish twins. SETTING: The Finnish twin cohort and the national hospital discharge register, covering the entire 5 million population of Finland. SUBJECTS: All same sex twin pairs born before 1946. The cohort contained 2308 monozygotic and 5241 dizygotic twin pairs (15 098 people) at the beginning of follow up. Main: outcome measure The number and concordance of osteoporotic fractures in the twin pairs, 1972-96. RESULTS: 786 cohort members sustained an osteoporotic fracture. In women, the pairwise concordance rate for fracture (that is, the relative number of twin pairs in whom the fracture affected both twins in a pair) was 9.5% (95% confidence interval 5.3% to 15.5%) in monozygotic pairs and 7.9% (5.2% to 11.4%) in dizygotic pairs. In men, the figures were 9.9% (4.4% to 18.5%) and 2.3% (0.6% to 5.7%). CONCLUSIONS: Susceptibility to osteoporotic fractures in elderly Finns is not strongly influenced by genetic factors, especially in elderly women. The traditional strategy for prevention of osteoporotic fractures-that is, increasing peak bone mass and preventing age related bone loss-should be changed to include new elements such as prevention of falls and protection of the critical anatomical sites of the body when a fall occurs.

Aged

Fall-induced injuries and deaths among older adults.

CONTEXT: Although various fall-induced injuries and deaths among older adults are increasing, little is known about the epidemiology of these events. OBJECTIVE: To determine the trends in the number and incidence of fall-induced injuries and deaths of older adults in a well-defined white population. DESIGN AND SETTING: Secular trend analysis of the population of Finland, using the Finnish National Hospital Discharge Register and the Official Cause-of-Death Statistics of Finland. PARTICIPANTS: All persons aged 50 years or older who were admitted to hospitals in Finland for primary treatment of a first fall-induced injury from the years of 1970 to 1995, and for comparison, all fall-induced deaths in the same age group from the years 1971 to 1995. MAIN OUTCOME MEASURE: The number and the age-specific and age-adjusted incidence rate (per 100000 persons) of fall-induced injuries and deaths in each year of the study. RESULTS: For the study period, both the total and population-adjusted number (per 100000 persons) of Finns aged 50 years or older with fall-induced injury increased substantially. Total fall-induced injuries increased from 5622 in 1970 to 21 574 in 1995, a 284% increase, and the rate increased from 494 to 1398 per 100000 persons, a 183% increase. The age-adjusted incidence also increased in both women (from 648 in 1970 to 1469 in 1995, a 127% increase) and men (from 434 in 1970 to 972 in 1995, a 124% increase). Moreover, the number of deaths due to falls in the overall population increased from 441 in 1971 to 793 in 1995, an 80% increase, and the rate increased from 38 in 1971 to 51 in 1995, a 34% increase. However, after age adjustment the incidence of fall-induced death did not show a clear upward trend. CONCLUSIONS: In a well-defined white population, the number of older persons with fall-induced injuries is increasing at a rate that cannot be explained simply by demographic changes. Preventive measures should be adopted to control the increasing burden of these injuries. Fortunately, the age-adjusted incidence of the fall-induced deaths shows no increasing trend over time.

Accidental Falls

Hip fractures in Finland between 1970 and 1997 and predictions for the future.

BACKGROUND: Hip fractures in elderly people are common worldwide, and the predicted ageing of populations is increasing the burden of these fractures on health-care systems. However, prediction of the true increases in number of patients needing treatment requires exact knowledge of whether the number of hip fractures is rising more rapidly than can be accounted for by demographic changes alone. We aimed to make such a prediction for people aged 50 years or more in Finland. METHODS: All patients aged 50 years or more, who were admitted to hospitals in Finland during 1970-97 for primary treatment of first hip fracture were selected from the National Hospital Discharge Register. The age-specific and age-adjusted fracture incidences were expressed as the number of patients per 100,000 individuals per year, and prediction of the number, and incidence of hip fractures in Finland (population 5 million) until the year 2030 was calculated with a regression model. FINDINGS: The number of hip fractures in Finnish people aged 50 or more rose during the study period, from 1857 in 1970 to 7122 in 1997. The corresponding fracture incidence (per 100,000 people) increased from 163 to 438. The age-adjusted incidence of hip fractures also showed a steady increase from 1970 to 1997: in women, from 292 to 467, and in men, from 112 to 233. If this trend continues, the number of hip fractures in Finland will be almost three-fold higher in the year 2030 than in 1997. INTERPRETATION: The number of hip fractures in elderly Finnish men and women is increasing at a rate that cannot be explained merely by demographic changes. The precise reasons for this are not known, but deterioration in age-adjusted bone-mineral density and strength, with accompanying increase in the age-adjusted incidence of injurious falls of the elderly, could partly account for the development.

Age Factors

Increasing number and incidence of fall-induced severe head injuries in older adults: nationwide statistics in Finland in 1970-1995 and prediction for the future.

To increase knowledge about recent trends in the number and incidence of various fall-induced injuries among older adults, the authors selected from the National Hospital Discharge Register all patients 60 years of age or older who were admitted to hospitals in Finland for primary treatment of a first fall-induced severe head injury during 1970-1995. Similar patients aged 30-39 years served as a reference group. For the study period, the number and incidence (per 100,000 persons) of fall-induced severe head injuries in Finnish persons 60 years of age or older increased considerably (554 and 85, respectively, in 1970 compared with 1,393 and 144, respectively, in 1995). The age-adjusted incidence of these injuries also increased in women, from 80 in 1970 to 125 in 1995, and in men, from 102 in 1970 to 147 in 1995. In the reference group (patients aged 30-39 years), the absolute numbers and incidences of similar injuries did not show consistent trend changes over time. We conclude that the number of fall-induced severe head injuries in elderly Finnish women and men is increasing at a rate that cannot be explained simply by demographic changes, and therefore vigorous preventive measures should be instituted at once to control the increasing burden of these devastating injuries.

Accidental Falls

Effect of anterior cruciate ligament injury of the knee on bone mineral density of the spine and affected lower extremity: a prospective one-year follow-Up study.

The objective of this 1-year prospective follow-up study was to assess, with dual-energy X-ray absorptiometry (DXA), the effect of an anterior cruciate ligament (ACL) injury of the knee on areal bone mineral density (BMD) of the injured extremity and lumbar spine in two separate patient groups: 21 surgically treated patients (group A) and 12 conservatively treated patients (group B). Clinical and functional status of the patients and BMD of the spine (L2-L4), dominant distal radius, femoral neck, trochanter area of the femur, distal femur, patella, proximal tibia, and calcaneus of both lower extremities were determined at the time of the injury and after 4, 8, and 12 months. A surgically treated, complete ACL rupture (group A) resulted in considerable and statistically significant bone loss to the affected knee (distal femur 21%, patella 17%, proximal tibia 14%; P < 0.001 in each), whereas the other sites were clearly less affected. Patients with a conservatively treated, complete or partial ACL injury (group B) had only a small but statistically significant bone loss at the patella (-3%; P = 0.005) and proximal tibia (-2%; P = 0.022) of the injured knee, and the other sites remained unchanged. The obvious differences between the groups A and B in the severity of the injury itself (complete or partial tear), its treatment (surgical or conservative), and subsequent rehabilitation (longer nonweight-bearing times in group A) explain these different BMD results, and the forthcoming years will show whether the considerable posttraumatic osteoporosis in the affected knee of group A patients will finally recover, and if so, to what extent.

Absorptiometry, Photon

Majority of hip fractures occur as a result of a fall and impact on the greater trochanter of the femur: a prospective controlled hip fracture study with 206 consecutive patients.

The objectives of this study were to learn how hip fracture patients fall, and to compare the mechanics of their falls with those falls that did not result in hip fracture. In this way we sought to obtain reliable insight into the etiology and pathogenesis of hip fracture and fracture prevention. A total of 206 consecutive patients with fresh hip fracture and 100 controls were interviewed and examined between October 1994 and May 1996. The only inclusion criterion was that the fracture had occurred within 24 hours of hospital admittance. The control subjects were admitted from the same community after an accidental fall that did not result in hip fracture. The characteristics of the accident were determined by personal interview and examination of the patients within 24 hours of the event. In 98% of the hip fracture patients, the fracture was a result of a fall. The majority of the patients (76%) reported that they had fallen directly to the side. Forty-eight fracture cases had one or more eyewitnesses and their reports supported this observation. In 56% of the hip fracture patients, a fresh subcutaneous hematoma was seen on the greater trochanter of the proximal femur; such a hematoma was rare in the controls (6%) (P < 0. 001), and this gave evidence for the direct impact of the greater trochanter during the fall of the hip fracture subjects. Most of the elderly fallers who fractured a hip did not manage to break the fall, e.g., with an outstretched arm. In conclusion, our results suggest that a typical hip fracture is the result of a fall and a subsequent impact on the greater trochanter of the proximal femur. The clinical implication of this finding is that effective prevention of hip fractures could be achieved by the diminution of the number and severity of falls of the elderly. We suggest that the severity of the falls (impacts on the greater trochanter) could be decreased by an external hip protector.

Accidental Falls

Bone-patellar tendon-bone reconstruction of the anterior cruciate ligament. A long-term comparison of early and late repair.

Ninety-one patients were assessed 5-9 years after an anterior cruciate ligament reconstruction (bone patella-tendon bone autograft). Forty-eight patients had been treated within 6 weeks of the injury (Group I) and 43 patients more than 3 months after the injury (Group II). 73 patients had either a normal or nearly normal final outcome. The mean Lysholm score was 82 and the mean Marshall score was 42. Eighty nine patients had normal or nearly normal stability in the operated knee when compared to the contralateral joint. In none of these results was there any significant difference between the groups. Results of functional and of isokinetic strength tests, as well as the presence of anterior knee pain, were also similar in both groups. However, patients with early reconstruction had fewer degenerative changes in the tibio-femoral joint and were more satisfied with the result. They also returned to their pre-injury level of sports activity more often than those patients in the late reconstruction group.

Adolescent

Comparison of force attenuation properties of four different hip protectors under simulated falling conditions in the elderly: an in vitro biomechanical study.

The purpose of this in vitro biomechanical study is to determine the force attenuation capacity of four different hip protectors (KPH1, KPH2, Safehip, and Safetypants) in falling simulations in elderly subjects (falls to the side). The simulated falling conditions were created by a biomechanical testing system, which consisted of an impact pendulum, surrogate pelvis and femur, and two load cells. Three series of impact experiments were conducted in an ascending order (low, moderate-, and high-force experiments), each exceeding the literature-provided average (+/- 1 SD) fracture threshold (3100 +/- 1200 N) of the proximal femur of elderly women with a mean age of 71 years. Using a low impact force of 4330 N, the trochanteric soft tissue (20-mm-thick polyethylene foam) attenuated the peak femoral impact force to 3740 N and, accordingly, the KPH1 protector to 590 N, KPH2 to 510 N, Safehip to 1080 N, and Safetypants to 790 N. Thus, in this low force experiment, all tested protectors could reduce the peak impact force entered into the proximal femur below the aforementioned average fracture threshold area (3100 +/-1200 N) of the proximal femur of elderly women. With a moderate impact force of 7230 N, the soft tissue attenuated the peak femoral impact force to 6130 N, and the protectors to 780 N, 760 N, 2240 N, and 2760 N, respectively. Thus, with this impact force, only the KPH hip protectors could reduce the impact force clearly below the fracture threshold area. In the final series of the experiment, the peak femoral impact force was set to be so high (10,840 N) that the protector, if effective, should prevent the hip fracture in almost all cases and situations. The trochanteric soft tissue attenuated this peak impact force to 9190 N, and the tested protectors to 1360 N, 1170 N, 4640 N, and 5770 N. Thus, with the KPH protectors the force received by the proximal femur remained below the average force required to fracture the proximal femur of elderly women, whereas with the two other protectors the impact force entered into the proximal femur clearly exceeded this threshold value. In conclusion, the test results showed that, of the four tested hip protectors, the anatomically designed energy-shunting and energy-absorbing KPH protectors can provide an effective impact force attenuation in a sideways-fall simulation in the elderly, whereas the force attenuation capacity of the two other protectors seems more limited. However, the true efficacy of any protector in the prevention of hip fractures can only be evaluated in randomized clinical trials.

Accidental Falls

Isokinetic muscle performance after surgery of the lateral ligaments of the ankle.

In this study, we assessed the isokinetic strength and power profile of 138 patients with a surgically treated lateral ligament injury of an ankle. In addition, the outcome predicting factors were analyzed. The measurements were done 6.2+/-0.8 years after the surgery using the Cybex II isokinetic dynamometer. The general strength status of the patients was good, the isokinetic testing showing no or only moderate (always < or = 18%) average strength deficits in the peak torque values of dorsiflexor and plantar flexor muscles of the injured ankle. Of the outcome predicting variables, only the age of the patient in the group with surgery for chronic ankle instability correlated significantly with the isokinetic peak torque deficits: the older the subject, the greater the peak torque deficit in the injured ankle (r(s) = -0.388 with p = 0.015) in ankle dorsiflexion at the speed of 60 degrees/s. In conclusion, patients having surgery for ankle ligament insufficiency, either in acute or chronic phase of the injury, seem to recover well showing no remarkable deficiencies in the isokinetic ankle muscle strengths several years after the repair.

Acute Disease

Changes in bone mineral content with decreased training in competitive young adult tennis players and controls: a prospective 4-yr follow-up.

PURPOSE: The purpose of this 4-yr prospective follow-up study of male tennis players was to determine the changes in the playing-to-nonplaying arm differences in bone mineral content (BMC) and answer two questions: 1) Are training induced bone gains lost with decreased training? and 2) Are the possible bone changes related to the changes in training? METHODS: Subjects were 13 former competitive male tennis players and their 13 controls. The players had started their playing career at the mean age of 11 yr. The initial comparisons between the playing and contralateral arms' BMC were done in 1992 (mean age 26 yr), and follow-up was performed 4 yr later. The players were competing at the national top level in the beginning of the study, and all had retired from the top tennis (mean) 2.3+/-0.6 yr before follow-up. Accordingly, they had reduced the average training frequency from 5.2 times a week to 2.6 times a week and the mean hours of training per week from 7.6 to 3.3. RESULTS: The 1996 measurements revealed that on average the players' exercise-induced bone gain in the playing arm had not disappeared with time despite decreased average playing activity and that observed bone changes were not related to changes in training. The side-to-side BMC differences were largest in the humeral shaft (25% in 1992 and 26% 4 yr later) and the proximal humerus (19% and 18%). The radial shaft difference was 14% and the distal radius difference 13% in both 1992 and 1996. In controls, the side-to-side BMC differences were small, less than 5%, and they did not change by time. CONCLUSIONS: In conclusion, this study suggests that bone gain obtained by regular tennis training does not disappear by time despite decreased playing activity. Regular exercise can be valuable for maximizing peak bone mass and thus contributing to prevention of osteoporosis and related fractures later in life.

Adult

Long-term functional outcome after surgery of chronic ankle instability. A 5-year follow-up study of the modified Evans procedure.

Chronic ankle instability is a rather common consequence of poorly healed rupture of the lateral ligaments of the ankle. In some rare cases, instability symptoms can be caused by general laxity of the joints, but since these cases are normally bilateral, they can easily be distinguished from posttraumatic instability. This report presents the long-term (average follow-up 4.6 years) functional outcome after a modified Evans tenodesis of 48 patients. The follow-up examination consisted of a questionnaire evaluating the subjective assessment of the ankle, and clinical examination measuring ankle stability, range of motion and swelling, and atrophy of the calf muscles. Additionally, the functional recovery of the ankle was assessed by a standardized performance test protocol. According to the subjective assessment, 25 subjects (52%) considered the ankle fully recovered, or at least much better than before surgery. In the performance test, however, only 17 subjects (35%) achieved an excellent or good score. In the performance test protocol, two functional tests, walking down a staircase and balancing on a square beam, best demonstrated the impaired function of the injured ankle. The modified Evans procedure could restore the stability of the ankle to the preinjury level, although the ankle range of motion was significantly impaired, and swelling of the ankle and atrophy of the calf muscles were frequent findings at the follow-up. In conclusion, surgical treatment of chronic ankle instability by the Evans procedure restores the mechanical stability of the joint, but too frequently the function of the ankle does not return to the pre-injury level.

Adolescent

Mechanical loading regulates tenascin-C expression in the osteotendinous junction.

Elastic extracellular matrix protein tenascin-C (TN) has very restricted expression in normal tissues, but is expressed in large quantities during embryogenesis and hyperplastic processes. To examine the importance of mechanical stress on the regulation of TN expression in vivo, the effects of various mechanical loading states (immobilization and three forms of subsequent remobilization) on the expression of TN were studied immunohistochemically at the bone-tendon attachment of the rat quadriceps muscle. This osteotendinous junction (OTJ) was selected as study site, since it receives its mechanical stimuli only from muscle contracting activity, which is easy to block by cast immobilization. TN was expressed abundantly in the normal OTJ. Following the removal of the mechanical stress from the junction by cast-immobilization of three weeks, the immunoreactivity of TN was almost completely absent. Normal mechanical stress in the form of free remobilization of eight weeks (free cage activity) resulted in a slight increase in TN expression, but could not restore the expression of TN to the level of the healthy contralateral leg. After the application of the increased mechanical stress (intensified remobilization of the eight weeks by low- or high-intensity treadmill running), the distribution and immunoreactivity of TN reached the level of the healthy contralateral limb in the low-intensity running group or even exceeded that in the high-intensity running group. High TN expression was seen around the chondrocytes and fibroblasts of the OTJ as well as around the collagen fibers of the tendon belly. We conclusively show that mechanical strain regulates the expression of TN in vivo, and propose that mechanical stress is a major regulator of TN expression in fibroblasts and chondrocytes. This may be an important aspect of the regulation of TN expression during embryogenesis, tendon degeneration, wound healing, bone formation, and in the other normal or regenerative morphogenetic processes TN is postulated to take part in.

Animals

Good maintenance of high-impact activity-induced bone gain by voluntary, unsupervised exercises: An 8-month follow-up of a randomized controlled trial.

The purpose of this study was to evaluate whether premenopausal women's voluntary unsupervised aerobic and step training could maintain the skeletal benefits obtained by an 18-month supervised high-impact training, and if so, to what extent. Thirty women of the original 39 study subjects (i. e., persons who completed the preceding 18-month randomized training intervention and who volunteered to continue the training on their own for a further 8 months) and 19 women of the 45 original control subjects (i.e., persons who volunteered to continue as controls) were included. The study group trained an average of twice per week and the training consisted of regular aerobic and step classes provided by local fitness centers. Areal bone mineral density (BMD, g/cm2) was measured from the lumbar spine, femoral neck, trochanter area of the femur, distal femur, patella, proximal tibia, calcaneus, and dominant distal radius at baseline and after 18 and 26 months. During the extended 8-month follow-up, the BMD of the study group increased more at the femoral neck (the intergroup change was +0.9% at 18 months and +2.8% at 26 months, p = 0.004 for the change between 18 and 26 months) and remained at the 18-month level at the distal femur, patella, proximal tibia, and calcaneus. In these sites, the statistically significant changes during the entire 26 months of training were 1.7-4.0% in the training group as compared with the changes of -0.9-1.5% in the control group. In the lumbar spine, BMD decreased from the 18-month level in both groups. In conclusion, the significant BMD increases that were obtained by supervised 18-month high-impact training were effectively maintained with subsequent unsupervised regular aerobic and step classes (twice per week). The finding emphasizes the effectiveness and feasibility of self-controlled aerobic and step exercises in the primary prevention of osteoporosis among healthy premenopausal women.

Adult

A tibial shaft fracture sustained in childhood or adolescence does not seem to interfere with attainment of peak bone density.

High peak bone mass or density in early adulthood is an important protective factor against osteoporotic fractures in later life, but it is not known whether injuries on growing bones affect the attainment of peak bone mass and density. The purpose of this study was therefore to examine with dual-energy X-ray absorptiometry the areal bone mineral density (BMD) of the injured and uninjured extremity (the femoral neck, trochanter area of the femur, distal femur, patella, proximal tibia, and distal tibia), lumbar spine, and distal radius of young adults with a history of early life tibial shaft fracture and to find out whether the fracture had affected the attainment of peak bone density of these patients. The second objective was to clarify whether any background or clinical follow-up variable would predict the BMD difference between the affected and unaffected extremity. Thus, the BMD and clinical status of 45 patients (34 men and 11 women), who had sustained a tibial shaft fracture in childhood or in adolescence (between 7 and 15 years of age) an average 11 years before the study, were examined. The results showed that the fracture had created a small but statistically significant injured-to-uninjured side BMD difference (proximal tibia -1.7%; p = 0.011, and distal tibia 2.6%; p = 0.014), while the other sites showed no significant side-to-side differences. There were neither significant differences in the spinal or radial BMDs between the patients and their age-, height-, and weight-matched healthy controls. A further analysis of the data showed that the better the muscle strength in the injured lower limb, the lower the side-to-side BMD deficit in the proximal tibia of the same limb (r = 0.51; p < 0.001). Smoking had a significant association with the relative BMD in the injured distal tibia (mean injured-to-uninjured side BMD difference: smokers 6.1% vs. nonsmokers -0.6%, p = 0.016). Also patient's age at the time of the injury showed an association: the younger the patient at the time of the injury, the lower the side-to-side BMD deficit in the injured distal tibia (r = -0.35; p = 0.048). In conclusion, this study indicates that early life tibial fracture leads to a small long-term BMD deficit in the fractured bone while the other sites of the skeleton seem not to be affected. Thus, a tibial shaft fracture sustained in childhood or adolescence seems to only marginally interfere the attainment of peak bone density, the important predictor of the osteoporotic fractures in later life.

Absorptiometry, Photon

Long-term recreational gymnastics, estrogen use, and selected risk factors for osteoporotic fractures.

The purpose of this cross-sectional study was to examine whether long-term participation in recreational gymnastics or folk dancing or estrogen replacement therapy (ERT) is associated with mechanically more competent bones and improved muscular strength and body balance. One hundred and seventeen healthy, female postmenopausal recreational gymnasts (mean age 62.1 [SD 4.7] years) and 116 sedentary controls (mean age 61.5 [4.6] years) were enrolled in the study. Bone mineral content (BMC) of the distal radius, femoral neck, and trochanter were measured with dual-energy X-ray absorptiometry. BMC of the midshaft and distal tibia and trabecular density (TrD) of the distal tibia were measured with peripheral computed quantitative tomography. Maximal isometric strength, muscular power, cardiorespiratory fitness, and body balance of the participants were also assessed. The cardiorespiratory fitness, muscular strength, and dynamic balance of the recreational gymnasts and folk dancers combined were significantly better than those of the controls, the average group difference ranging from 7.5% (95% confidence interval 5.0-9.9%) in dynamic balance to 12.8% (6.6-19. 4%) in dynamic muscular power. ERT was not associated with the fitness indicators, muscular power, or balance, but was significantly associated with the BMC at all the measured bone sites, the mean group difference between estrogen users and nonusers ranging from 6.5% (3.7-9.3%) for the tibial shaft to 11.8% (6.4-17. 0%) for the distal radius. Recreational gymnastics, in turn, was significantly associated with higher BMC at the tibia only, the mean group difference being 3.9% (0.9-6.9%) for the tibial shaft and 7.7% (3.7-11.9%) for the distal tibia. Recreational gymnastics was also associated with higher TrD at the distal tibia (5.2%; 1.2-9.2%), whereas estrogen usage did not show such association. The results indicate that ERT seems especially effective in preventing postmenopausal bone loss, whereas recreational gymnastics and folk dancing improve muscular performance and body balance in addition to increased bone mass and bone size in the tibia. All these factors are essential in prevention of fall-related fractures of the elderly.

Absorptiometry, Photon

An outcome study of chronic patellofemoral pain syndrome. Seven-year follow-up of patients in a randomized, controlled trial.

BACKGROUND: We determined prospectively the long-term outcomes of nonoperative treatment of chronic patellofemoral pain syndrome. METHODS: Of forty-nine patients in a prospective, randomized, double-blind study of unilateral chronic patellofemoral pain syndrome in the knee, forty-five were reexamined seven years after the initial trial of treatment. In the earlier trial, the short-term (six-month) effects of intra-articular injections of glycosaminoglycan polysulfate combined with intensive quadriceps-muscle exercises were compared with those of injections of a placebo combined with exercises and with those of exercises alone. At seven years, the follow-up consisted of standardized subjective, functional, and clinical assessments and muscle-strength measurements as well as magnetic resonance imaging, radiography, and bone-densitometry measurements of the knee. RESULTS: At six months, complete subjective, functional, and clinical recovery had occurred in almost three-fourths of the patients and, with the numbers available for study, neither significant nor clinically important differences among the three initial treatment groups were detected. The subjective and functional parameters showed few changes between six months and seven years; almost three-fourths of the patients still had full subjective and functional recovery at the time of the latest follow-up. However, according to the physician's clinical evaluation, the number of patients who had no symptoms on the patellar compression and apprehension tests decreased over time, from forty-two (93 percent) and forty (89 percent) of forty-five patients at six months to thirty (67 percent) and thirty-one (69 percent) at seven years; these changes were significant (p = 0.002 and p = 0.023, respectively). The number of patients who had crepitation on the patellar compression test increased over time, from twenty-six (58 percent) at six months to thirty-six (80 percent) at seven years (p = 0.021). The physician's overall assessment showed a similar trend, with thirty-four patients (76 percent) having had complete recovery at six months compared with thirty (67 percent) at seven years; however, with the numbers available, this change was not significant (p = 0.420). Magnetic resonance imaging, performed for thirty-seven patients, revealed no abnormalities in twenty-four (65 percent), mild abnormalities in four (11 percent), moderate abnormalities (a 25 to 75 percent decrease in the thickness of the cartilage) in seven (19 percent), and overt patellofemoral osteoarthritis in two (5 percent) at seven years. CONCLUSIONS: The seven-year overall outcome was good in approximately two-thirds of the patients. However, the remaining patients still had symptoms or objective signs of a patellofemoral abnormality.

Adult