Effect of physical activity on cartilage development in healthy kids

Mean femoral cartilage thickness is higher in athletes as compared with sedentary individuals

PURPOSE

It is unclear how high-intensity physical activity (HIPA) affects the knee joint, specifically the femoral cartilage (FC). Therefore, the aims of this study were to evaluate FC thickness via ultrasound among elite athletes involved in different types of HIPA, and to determine whether there is a correlation between serum cartilage oligomeric matrix protein (sCOMP) and rectus femoris (RF) thickness.

METHOD

A total of 132 male individuals participated in this study and were assigned to two groups, the sedentary (n = 43, 23.9 ± 3.7) and athlete groups (n = 89, 22.7 ± 4.6), which did not significantly differ in age. The athletes were elite and performed HIPA during sports such as volleyball (n = 20), soccer (n = 21), basketball (n = 28), and weightlifting (n = 20). RF thickness and three (mid-point) measurements were obtained for each knee. The mean FC thickness for each knee was defined as the sum of the medial, lateral condyles, and intercondylar areas. Blood samples for sCOMP analyses were also obtained.

RESULTS

All the measurements of the FC of both knees were significantly higher in the athletes than in the sedentary individuals (p < 0.001 and p = 0.001). The mean right and left FC values were also higher in the athletes (p < 0.001). Multiple linear regression analysis showed that participation in sporting activities was a significant predictor associated with the right and left mean FC thickness (p < 0.001 for both). No significant differences in the sCOMP levels were found between the two groups.

CONCLUSION

It was found that the mean FC was higher among athletes than among sedentary individuals. As a result, it is suggested that sports' participation is an independent factor associated with the right and left mean FC thickness.

LEVEL OF EVIDENCE

III.

Does Injection of Hyaluronic Acid Protect Against Early Cartilage Injury Seen After Marathon Running? A Randomized Controlled Trial Utilizing High-Field Magnetic Resonance Imaging

BACKGROUND

Previous studies have shown that runners demonstrate elevated T2 and T1ρ values on magnetic resonance imaging (MRI) after running a marathon, with the greatest changes in the patellofemoral and medial compartment, which can persist after 3 months of reduced activity. Additionally, marathon running has been shown to increase serum inflammatory markers. Hyaluronic acid (HA) purportedly improves viscoelasticity of synovial fluid, serving as a lubricant while also having chondroprotective and anti-inflammatory effects.

PURPOSE/HYPOTHESIS

The purpose was to investigate whether intra-articular HA injection can protect articular cartilage from injury attributed to marathon running. The hypothesis was that the addition of intra-articular HA 1 week before running a marathon would reduce the magnitude of early cartilage breakdown measured by MRI.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

After institutional review board approval, 20 runners were randomized into receiving an intra-articular injection of HA or normal saline (NS) 1 week before running a marathon. Exclusionary criteria included any prior knee injury or surgery and having run >3 prior marathons. Baseline 3-T knee MRI was obtained within 48 hours before the marathon (approximately 5 days after injection). Follow-up 3-T MRI scans of the same knee were obtained 48 to 72 hours and 3 months after the marathon. The T2 and T1ρ relaxation times of articular cartilage were measured in 8 locations-the medial and lateral compartments (including 2 areas of each femoral condyle) and the patellofemoral joint. The statistical analysis compared changes in T2 and T1ρ relaxation times (ms) from baseline to immediate and 3-month postmarathon scans between the HA and NS groups with repeated measures analysis of variance.

RESULTS

Fifteen runners completed the study: 6 women and 2 men in the HA group (mean age, 31 years; range, 23-50 years) and 6 women and 1 man in the NS group (mean age, 27 years; range, 20-49 years). There were no gross morphologic MRI changes after running the marathon. Postmarathon studies revealed no statistically significant changes between the HA and NS groups in all articular cartilage areas of the knee on both T2 and T1ρ relaxation times.

CONCLUSION

Increased T2 and T1ρ relaxation times have been observed in marathon runners, suggesting early cartilage injury. The addition of intra-articular HA did not significantly affect relaxation times in all areas of the knee when compared with an NS control.

Baseline knee adduction moment interacts with body mass index to predict loss of medial tibial cartilage volume over 2.5 years in knee Osteoarthritis

This study aimed to determine the extent to which changes over 2.5 years in medial knee cartilage thickness and volume were predicted by: (1) Peak values of the knee adduction (KAM) and flexion moments; and (2) KAM impulse and loading frequency, representing cumulative load, after controlling for age, sex and body mass index (BMI). Adults with clinical knee osteoarthritis participated. At baseline and approximately 2.5 years follow-up, cartilage thickness and volume of the medial tibia and femur were segmented from magnetic resonance imaging scans. Gait kinematics and kinetics, and daily knee loading frequency were also collected at baseline. Multiple linear regressions predicted changes in cartilage morphology from baseline gait mechanics. Data were collected from 52 participants (41 women) [age 61.0 (6.9) y; BMI 28.5 (5.7) kg/m² ] over 2.56 (0.51) years. There were significant KAM peak-by-BMI (p = 0.023) and KAM impulse-by-BMI (p = 0.034) interactions, which revealed that larger joint loads in those with higher BMIs were associated with greater loss of medial tibial cartilage volume. In conclusion, with adjustments for age, sex, and cartilage measurement at baseline, large magnitude KAM peak and KAM impulse each interacted with BMI to predict loss of cartilage volume of the medial tibia over 2.5 years among individuals with knee osteoarthritis. These data suggest that, in clinical knee osteoarthritis, exposure to large KAMs may be detrimental to cartilage in those with larger BMIs. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2476-2483, 2017.

Osteoarthritis in Football

Football is currently the most popular sporting activity in the world. Multiple reports have shown that a high incidence of osteoarthritis is found in football players. Evidence clearly shows that traumatic injury significantly predisposes players for such pathophysiology. Injuries are frequent in amateur as well as professional football players, with knee and ankle accounting for the most severe injuries. Many professional athletes lose playing time due to injuries and many are forced into early retirement. Posttraumatic osteoarthritis is a common finding among ex-football players with numbers well above the normal population. Today's surgical techniques are advanced and capable of restoring the joint to a certain extent. However, a restitution ad integrum is reached only in very rare cases. Professional football players that return to play after serious injuries perform their extremely strenuous activity on morphologically compromised joints. Incomplete rehabilitation and pressure to return to play after an injurious event clearly put the athlete at an even higher risk for joint degeneration. Prevention strategies, improved surgical management, strict rehabilitation, as well as future aspects such as early suppression of inflammation, personalized medicine, and predictive genomics DNA profiling are needed to reduce incidence and improve the health perspectives of football players.

Polymers in Cartilage Defect Repair of the Knee: Current Status and Future Prospects

Cartilage defects in the knee are often seen in young and active patients. There is a need for effective joint preserving treatments in patients suffering from cartilage defects, as untreated defects often lead to osteoarthritis. Within the last two decades, tissue engineering based techniques using a wide variety of polymers, cell sources, and signaling molecules have been evaluated. We start this review with basic background information on cartilage structure, its intrinsic repair, and an overview of the cartilage repair treatments from a historical perspective. Next, we thoroughly discuss polymer construct components and their current use in commercially available constructs. Finally, we provide an in-depth discussion about construct considerations such as degradation rates, cell sources, mechanical properties, joint homeostasis, and non-degradable/hybrid resurfacing techniques. As future prospects in cartilage repair, we foresee developments in three areas: first, further optimization of degradable scaffolds towards more biomimetic grafts and improved joint environment. Second, we predict that patient-specific non-degradable resurfacing implants will become increasingly applied and will provide a feasible treatment for older patients or failed regenerative treatments. Third, we foresee an increase of interest in hybrid construct, which combines degradable with non-degradable materials.

Compressive and shear hip joint contact forces are affected by pediatric obesity during walking

Obese children exhibit altered gait mechanics compared to healthy-weight children and have an increased prevalence of hip pain and pathology. This study sought to determine the relationships between body mass and compressive and shear hip joint contact forces during walking. Kinematic and kinetic data were collected during treadmill walking at 1ms(-1) in 10 obese and 10 healthy-weight 8-12 year-olds. We estimated body composition, segment masses, lower-extremity alignment, and femoral neck angle via radiographic images, created personalized musculoskeletal models in OpenSim, and computed muscle forces and hip joint contact forces. Hip extension at mid-stance was 9° less, on average, in the obese children (p<0.001). Hip abduction, knee flexion, and body-weight normalized peak hip moments were similar between groups. Normalized to body-weight, peak contact forces were similar at the first peak and slightly lower at the second peak between the obese and healthy-weight participants. Total body mass explained a greater proportion of contact force variance compared to lean body mass in the compressive (r(2)=0.89) and vertical shear (perpendicular to the physis acting superior-to-inferior) (r(2)=0.84) directions; lean body mass explained a greater proportion in the posterior shear direction (r(2)=0.54). Stance-average contact forces in the compressive and vertical shear directions increased by 41N and 48N, respectively, for every kilogram of body mass. Age explained less than 27% of the hip loading variance. No effect of sex was found. The proportionality between hip loads and body-weight may be implicated in an obese child׳s increased risk of hip pain and pathology.

Pediatric obesity and walking duration increase medial tibiofemoral compartment contact forces

With the high prevalence of pediatric obesity there is a need for structured physical activity during childhood. However, altered tibiofemoral loading during physical activity in obese children likely contribute to their increased risk of orthopedic disorders of the knee. The goal of this study was to determine the effects of pediatric obesity and walking duration on medial and lateral tibiofemoral contact forces. We collected experimental biomechanics data during treadmill walking at 1 m•s(-1) for 20 min in 10 obese and 10 healthy-weight 8-12 year-olds. We created subject-specific musculoskeletal models using radiographic measures of tibiofemoral alignment and centers-of-pressure, and predicted medial and lateral tibiofemoral contact forces at the beginning and end of each trial. Obesity and walking duration affected tibiofemoral loading. At the beginning of the trail, the average percent of the total load passing through the medial compartment during stance was 85% in the obese children and 63% in the healthy-weight children; at the end of the trial, the medial distribution was 90% in the obese children and 72% in the healthy-weight children. Medial compartment loading rates were 1.78 times greater in the obese participants. The medial compartment loading rate increased 17% in both groups at the end compared to the beginning of the trial (p = 0.001). We found a strong linear relationship between body-fat percentage and the medial-lateral load distribution (r(2) = 0.79). Altered tibiofemoral loading during walking in obese children may contribute to their increased risk of knee pain and pathology.

Association of physical activity and physical performance with tibial cartilage volume and bone area in young adults

Introduction

Physical activity has been recommended to patients with knee osteoarthritis for improving their symptoms. However, it is still controversial if physical activity has effects on joint structures including cartilage volume. The aim of this study was to describe the associations between physical activity and performance measured 5 years prior and tibial cartilage volume and bone area in young adults.

Methods

Subjects broadly representative of the Australian population (n = 328, aged 31–41 years, female 47.3 %) were selected from the Childhood Determinants of Adult Health study. They underwent T1-weighted fat-suppressed magnetic resonance imaging (MRI) scans of their knees. Tibial bone area and cartilage volume were measured from MRI. Physical activity (measured using long international physical activity questionnaire (IPAQ)) and performance measures (long jump, leg muscle strength, physical work capacity (PWC₁₇₀)) were measured 5 years prior.

Results

In multivariable analyses, total physical activity (min/week) (β: 0.30 mm³, 95 % CI: 0.13,0.47), vigorous (β: 0.54 mm³, 95 % CI: 0.13,0.94), moderate (β: 0.34 mm³, 95 % CI: 0.01,0.67), walking (β: 0.40 mm³, 95 % CI: 0.07,0.72) and IPAQ category (β: 182.9 mm³, 95 % CI: 51.8,314.0) were positively associated with total tibial cartilage volume but not tibial bone area. PWC₁₇₀, long jump and leg muscle strength were positively and significantly associated with both total tibial cartilage volume and total tibial bone area; and the associations with tibial cartilage volume decreased in magnitude but remained significant for PWC₁₇₀ and long jump after further adjustment for tibial bone area.

Conclusion

While tibial bone area is affected only by physical performance, total tibial cartilage volume can be influenced by both physical activity and performance in younger adults. The clinical significance suggests a beneficial effect for cartilage but the bone area association was restricted to performance suggesting other factors rather than physical activity may be important.

Different exercise modalities have distinct effects on the integrin-linked kinase (ILK) and Ca2+ signaling pathways in the male rat bone

Mechanical loading is essential to maintain optimal skeletal health. Despite the fact that early-life exercise has positive, long-lasting effects on the musculo-skeletal system, the response of the musculo-skeletal system to spontaneous low-impact exercise has been poorly studied. Previously, we identified subtle morphological changes in the femoral diaphysis of exercised animals compared to nonexercised controls. We hypothesized that significant changes in gene expression of cells should precede significant measurable phenotypic changes in the tissues of which they are part. Here, we employed RNA-Seq to analyse the transcriptome of the cortical bone from the femoral mid-diaphysis of prepubertal male Sprague-Dawley rats that were assigned to control (CON); bipedal stance (BPS); or wheel exercise (WEX) groups for 15 days. We identified 808 and 324 differentially expressed transcripts in the BPS and WEX animals respectively. While a number of transcripts change their levels in an exercise-specific manner, we identified 191 transcripts that were differentially expressed in both BPS and WEX. Importantly, we observed that the exercise mode had diametrically opposite effects on transcripts for multiple genes within the integrin-linked kinase (ILK) and Ca(2+) signaling pathways such that they were up-regulated in BPS and down-regulated in WEX. The findings are important for our understanding of possible ways in which different exercise regimens might affect bone when normal activities apply mechanical stimuli during postnatal growth and development.

Cartilage issues in football-today's problems and tomorrow's solutions

Articular cartilage injury is prevalent in football players and results from chronic joint stress or acute traumatic injuries. Articular cartilage injury can often result in progressive painful impairment of joint function and limit sports participation. Management of articular cartilage injury in athletes aims to return the player to competition, and requires effective and durable joint surface restoration that resembles normal hyaline articular cartilage that can withstand the high joint stresses of football. Existing articular cartilage repair techniques can return the athlete with articular cartilage injury to high-impact sports, but treatment does not produce normal articular cartilage, and this limits the success rate and durability of current cartilage repair in athletes. Novel scientific concepts and treatment techniques that apply modern tissue engineering technologies promise further advancement in the treatment of these challenging injuries in the high demand athletic population. We review the current knowledge of cartilage injury pathophysiology, epidemiology and aetiology, and outline existing management algorithms, developing treatment options and future strategies to manage articular cartilage injuries in football players.

Current concepts for rehabilitation and return to sport after knee articular cartilage repair in the athlete

Articular cartilage injury is observed with increasing frequency in both elite and amateur athletes and results from the significant acute and chronic joint stress associated with impact sports. Left untreated, articular cartilage defects can lead to chronic joint degeneration and athletic and functional disability. Treatment of articular cartilage defects in the athletic population presents a therapeutic challenge due to the high mechanical demands of athletic activity. Several articular cartilage repair techniques have been shown to successfully restore articular cartilage surfaces and allow athletes to return to high-impact sports. Postoperative rehabilitation is a critical component of the treatment process for athletic articular cartilage injury and should take into consideration the biology of the cartilage repair technique, cartilage defect characteristics, and each athlete's sport-specific demands to optimize functional outcome. Systematic, stepwise rehabilitation with criteria-based progression is recommended for an individualized rehabilitation of each athlete not only to achieve initial return to sport at the preinjury level but also to continue sports participation and reduce risk for reinjury or joint degeneration under the high mechanical demands of athletic activity.

Mechanical loading: bone remodeling and cartilage maintenance

Bone remodeling and cartilage maintenance are strongly influenced by biomechanical signals generated by mechanical loading. Although moderate loading is required to maintain bone mass and cartilage homeostasis, loading can cause deleterious effects such as bone fracture and cartilage degradation. Because a tight coupling exists between cartilage and bone, alterations in one tissue can affect the other. Bone marrow lesions are often associated with an increased risk of developing cartilage defects, and changes in the articular cartilage integrity are linked to remodeling responses in the underlying bone. Although mechanisms regulating the maintenance of these two tissues are different, compelling evidence indicates that the signal pathways crosstalk, particularly with the Wnt pathway. A better understanding of the complex tempero-spatial interplay between bone remodeling and cartilage degeneration will help develop a therapeutic loading strategy that prevents bone loss and cartilage degeneration.

Bone mineral density is cross sectionally associated with cartilage volume in healthy, asymptomatic adult females: Geelong Osteoporosis Study

INTRODUCTION

The association between osteoporosis and osteoarthritis (OA) is controversial. Although previous studies have shown total body, lower limb, spinal and knee BMD and knee cartilage volume to be positively associated, the relationship between other distant site-specific measures of BMD and other knee structures is unknown. The aim of this study was to determine the associations between BMD at eight skeletal sites, and knee structure in asymptomatic young to middle-aged females without any clinical signs of OA.

METHODS

One hundred and sixty healthy, asymptomatic females (29-50 yr) underwent magnetic resonance imaging of the knee. BMD was measured at the spine, hip, total body and forearm by dual energy X-ray absorptiometry, and at the calcaneus by quantitative ultrasound. BMD was tested for an association with cartilage volume, defects, and bone marrow lesions (BMLs).

RESULTS

Medial cartilage volume was positively associated with BMD at the spine, total body, femoral neck, and Ward's triangle (all p<0.05), with non-significant associations in the same direction at the trochanter (p=0.07). Findings in the lateral compartment were similar. The presence of medial cartilage knee defects were also associated with BMD at the spine; defects in the lateral compartment were associated with BMD at the forearm (both p=0.05). BMD was not associated with the presence of BMLs. No associations were observed with calcaneus BMD.

CONCLUSIONS

Site-specific BMD is associated with cartilage volume at the knee in asymptomatic young to middle-aged adults, with the direction and effects trending in the same direction. The magnitude of changes correlates with clinically relevant changes. QUS defined calcaneus BMD, showed no associations with knee structure. Although systemic factors may underlie the association between knee cartilage volume and axial/lower limb BMD, these data suggest that common local, possibly biomechanical factors may also play a role.

Mild exercise early in life produces changes in bone size and strength but not density in proximal phalangeal, third metacarpal and third carpal bones of foals

Exercise or lack of it in early life affects chondro-osseous development. Two groups of horses were used to investigate the effects of age and exercise regimen on bone parameters of diaphyseal, metaphyseal, epiphyseal and cuboidal bones of the distal limb of Thoroughbreds. One group had exercised only spontaneously from an early age at pasture (PASTEX group), while the other group of horses were exposed to a 30% greater workload through additional defined exercise (CONDEX). Longitudinal data from peripheral quantitative computed tomography (pQCT) were obtained from eight scan sites of the left forelimb (proximal phalangeal (P(p); 1 site), third metacarpal (Mc3; six sites) and third carpal (C(3); one site) bones) of 32 Thoroughbred foals scanned five times from ∼3 weeks to 17 months of age. The primary outcome measures were bone mineral content (BMC), bone area (BA), and periosteal circumference (Peri C) in diaphyseal bone, with cortical thickness (CortTh), volumetric bone mineral density (BMD(v)) and a bone strength index (SSI) also being analysed. At the P(p) site within the model there was a significant effect (P=0.00-0.025) of conditioning exercise increasing bone parameters, except endosteal circumference (Endo C) and BMD(v). The BMC, BA, and SSI of P(p) were significantly greater in the CONDEX than PASTEX groups at 12 and 17 months (P=0.015-0.042) and CortTh at 17 months (P=0.033). At the M55 site of Mc3 BMC, BA and SSI (P=0.02-0.04), and at the M33 site, SSI (P=0.05) were higher in the CONDEX than PASTEX group. The adaptive responses, consistent with diaphyseal strengthening, were more marked in the diaphysis of P(p) than Mc3. In the Mc3, metaphysis, trabecular BMD(v) was less in the CONDEX than PASTEX group, associated with greater bone mineral accretion in the outer cortical-sub-cortical bone in the CONDEX group. There were no significant between-group differences in any epiphyseal or cuboidal bone parameter. Although the early imposed exercise regimen was not intensive, it had significant effects on diaphyseal bone strength, through change in size but not bone density.

Ultrasonographic measurements of joint cartilage thickness in healthy children: age- and sex-related standard reference values

OBJECTIVE

Loss of joint cartilage may be an early feature of chronic inflammatory joint diseases like juvenile idiopathic arthritis (JIA). Conventional radiography usually detects only late changes such as joint space narrowing and bone erosion rather than early inflammatory changes. Joint cartilage is easily visualized with high-frequency ultrasonography (US), but age- and gender-related normal standard reference values should be established before US measurement of cartilage thickness becomes standard procedure in the clinic.

METHODS

A cross-sectional study of bilateral grey-scale US cartilage thickness of the knee, ankle, wrist, and second metacarpophalangeal (MCP) and second proximal interphalangeal (PIP) joints was performed in 394 (215 boys/179 girls) healthy Danish Caucasian children aged between 7 and 16 years.

RESULTS

Cartilage thickness differed significantly between sexes (p < 0.001 for all joints), boys having thicker cartilage than girls. Cartilage thickness clearly decreased with increasing age in both sexes. A formula for calculating sex-specific cartilage thickness at different ages in childhood is suggested. No difference between the right and left side of the investigated joints was observed.

CONCLUSION

Using US, we established age- and sex-related normal reference intervals for cartilage thickness of the knee, ankle, wrist, and MCP and PIP joints in 7- to 16-year-old children, and designed a formula for calculating hyaline cartilage thickness in all age groups throughout childhood.

New developments in osteoarthritis. Prevention of injury-related knee osteoarthritis: opportunities for the primary and secondary prevention of knee osteoarthritis

Where risk factors have been identified in knee and hip osteoarthritis (OA), with few exceptions, no prevention strategies have proven beneficial. The major risk factors for knee OA are advanced age, injury and obesity. However, there is limited or no evidence that they are modifiable or to what degree modifying them is effective in preventing development of knee OA or in preventing symptoms and progressive disease in persons with early OA. The notable exception is the growing epidemic of (sports) injury related knee OA. This review details the biological and clinical data indicating the efficacy of interventions targeting neuromuscular and biomechanical factors that make this subset of OA an attractive public health target, and highlights research opportunities for the future.

Articular Cartilage Injury in Athletes

Articular cartilage lesions in the athletic population are observed with increasing frequency and, due to limited intrinsic healing capacity, can lead to progressive pain and functional limitation over time. If left untreated, isolated cartilage lesions can lead to progressive chondropenia or global cartilage loss over time. A chondropenia curve is described to help predict the outcome of cartilage injury based on different lesion and patient characteristics. Nutriceuticals and chondroprotective agents are being investigated as tools to slow the development of chondropenia. Several operative techniques have been described for articular cartilage repair or replacement and, more recently, cartilage regeneration. Rehabilitation guidelines are being developed to meet the needs of these new techniques. Next-generation techniques are currently evaluated to optimize articular cartilage repair biology and to provide a repair cartilage tissue that can withstand the high mechanical loads experienced by the athlete with consistent long-term durability.

Rehabilitation after autologous chondrocyte implantation in athletes

Over the years a variety of cartilage restorative procedures have been developed for athletes to address focal, full-thickness cartilaginous defects in the knee joint, including microfracture, osteochondral autografts, osteochondral allografts, autologous chondrocyte implantation (ACI), and most recently, next-generation ACI involving scaffolds or cell-seeded scaffolds. Since its introduction, ACI has yielded some very promising results in athletes and nonathletes alike. Rehabilitation following ACI requires an in-depth understanding of joint mechanics, and knowledge of the biologic and biomechanical properties of healing articular cartilage. A patient-, lesion-, and sports-specific approach is required on the part of the trainer or physical therapist to gradually restore knee joint function and strength so that the athlete may be able to return to competitive play. This article reviews the rehabilitation protocols for injured athletes following an ACI procedure.

Effect of exercise on thicknesses of mature hyaline cartilage, calcified cartilage, and subchondral bone of equine tarsi

OBJECTIVE-To investigate effects of exercise on hyaline cartilage (HC), calcified cartilage (CC), and subchondral bone (SCB) thickness patterns of equine tarsi. SAMPLE POPULATION-30 tarsi from cadavers of horses with known exercise history. PROCEDURES-Tarsi were assigned to 3 groups according to known exercise history as follows: pasture exercise only (PE tarsi), low-intensity general-purpose riding exercise (LE tarsi), and high-intensity elite competition riding exercise (EE tarsi). Osteochondral tissue from distal tarsal joints underwent histologic preparation. Hyaline cartilage, CC, and SCB thickness were measured at standard sites at medial, midline, and lateral locations across joints with a histomorphometric technique. RESULTS-HC, CC, and SCB thickness were significantly greater at all sites in EE tarsi, compared with PE tarsi; this was also true when LE tarsi were compared with PE tarsi. At specific sites, HC, CC, and SCB were significantly thicker in EE tarsi, compared with LE tarsi. Along the articular surface of the proximal aspect of the third metatarsal bone, SCB was thickest in EE tarsi and thinnest in LE tarsi; increases were greatest at sites previously reported to undergo peak strains and osteochondral damage. CONCLUSIONS AND CLINICAL RELEVANCE-Increased exercise was associated with increased HC, CC, and SCB thickness in mature horses. At sites that undergo high compressive strains, with a reported predisposition to osteoarthritic change, there was increased CC and SCB thickness. These results may provide insight into the interaction between adaptive response to exercise and pathological change.

Does intensive rehabilitation permit early return to sport without compromising the clinical outcome after arthroscopic autologous chondrocyte implantation in highly competitive athletes?

BACKGROUND

Despite improvement in treatment for articular cartilage lesions, prolonged recovery still precludes early return to competitive sports. The challenge of postoperative rehabilitation is to optimize return to preinjury activities without jeopardizing the graft.

HYPOTHESIS

Intensive rehabilitation after second-generation arthroscopic autologous cartilage implantation (Hyalograft C) facilitates graft maturation and safely allows for early return to competition without jeopardizing clinical outcome at longer follow-up.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The outcome of 31 competitive male athletes with International Cartilage Repair Society grade III-IV cartilaginous lesions of the medial or lateral femoral condyle or trochlea were evaluated at 1-, 2-, and 5-year follow-up. The athletic cohort was compared with a similar control cohort of 34 nonathletic patients who were treated with autologous chondrocyte implantation. The athletic cohort followed a 4-phase intensive rehabilitation protocol. Eleven of the patients in this cohort were also treated with an isokinetic exercise program and on-field rehabilitation. The patients in the control cohort completed only phase 1 of rehabilitation.

RESULTS

When comparing the 2 groups, a greater improvement in the group of athletes was achieved at 5-year follow-up (P = .037) in the self-assessment of quality of life and International Knee Documentation Committee subjective evaluation at 12 months and at 5 years of follow-up (P = .001 and P = .002, respectively). When analyzing the return to sports activity, 80.6% of the athletes returned to their previous activity level in 12.4 +/- 1.6 months; athletes treated with the on-field rehabilitation and isokinetic exercise program had faster recovery and an even earlier return to competition (10.6 +/- 2.0 months).

CONCLUSION

For optimal results, autologous chondrocyte implantation rehabilitation should not only follow but also facilitate the process of graft maturation. Intensive rehabilitation may safely allow a faster return to competition and also influence positively the clinical outcome at medium-term follow-up.

The determinants of change in patella cartilage volume--a cohort study of healthy middle-aged women

OBJECTIVES

Although cartilage loss occurs with advancing age and is a hallmark of OA, the factors that affect cartilage change are not well established. The aim of this study was to explore the determinants of change in patella cartilage volume over 2 yrs among healthy middle-aged women with no clinical knee OA.

METHODS

One hundred and forty-eight women with no clinical knee OA were recruited from a previous population-based cross-sectional study of healthy women aged 40-67 yrs. MRI was performed at baseline and at 2 yrs, to assess patella cartilage and bone volume. Self-reported exercise was assessed by questionnaire.

RESULTS

Annual loss of patella cartilage volume was 1.6% (95% CI 1.2, 1.9). Age was positively associated with patella cartilage volume loss after adjustment for confounders (P = 0.05). For every 1 mm(3) increase in patella bone volume at baseline, annual cartilage loss was reduced by 8.05 mm(3) (95% CI 12.91, 3.19; P < 0.001). Fortnightly participation in exercise promoting an increased heart and respiratory rate for at least 20 min also tended to be associated with a reduced rate of patella cartilage volume loss (P = 0.09).

CONCLUSION

Among middle-aged women with no clinical knee OA, advancing age expedites the rate of patella cartilage volume loss, while increased patella bone volume and exercise participation tends to be associated with a reduction in the rate of patella cartilage volume loss. Interventions targeting modifiable factors, such as physical activity, warrant further investigation as they may help to prevent patellofemoral OA.

Allometric relationships between knee cartilage volume, thickness, surface area and body dimensions

OBJECTIVE

To determine if anthropometric factors obtainable on routine examination can be used to estimate premorbid knee total subchondral bone area (tAB), cartilage surface area (AC), cartilage thickness (ThC), and cartilage volume (VC).

METHOD

Young individuals (21-39 years old) without history of knee joint pain, injury or disease were studied. Magnetic resonance imaging of the right knee was used to determine tAB, AC, ThC and VC for knee cartilage. Multilinear regression and curve fitting by variance minimization were used to model the data.

RESULTS

VC and AC closely depended on tAB(1.5) in both men and women. This relationship subsumed all dependency on sex, height, weight and body mass index. In females, VC depended on height cubed and tAB on height squared. The relationship was much weaker in males. ThC was poorly related to tAB and VC. Confidence limits for VC standardized to tAB(1.5) were narrower than standardization to tAB or height.

CONCLUSION

The absence of a tight relationship of VC and tAB with height in males suggests that the factors stimulating bone and cartilage growth may be different between sexes. The high correlation between tAB and VC across both sexes suggests, however, that (opposite to measures from routine clinical examination) tAB(1.5) can provide individual reference values for VC, against which changes with age and disease can be estimated with high confidence.

Importance of sports in cartilage regeneration after autologous chondrocyte implantation: a prospective study with a 3-year follow-up

BACKGROUND

There have been no data in the literature reporting the influence of sports on the outcome of autologous chondrocyte implantation in chondral defects of the knee.

HYPOTHESIS

Sports can improve the result of autologous chondrocyte implantation in postoperative follow-up.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Between 1997 and 2003, 118 patients with symptomatic isolated chondral lesions of the knee underwent autologous chondrocyte implantation. According to the sports activity level before the start of symptoms, patients were assigned to 2 groups: group II with no or rare sports involvement (1-3 times/month); group I with regular (1-3 times/week) or competitive sports (4-7 times/week). All patients underwent clinical and magnetic resonance imaging evaluation preoperative and 6, 18, and 36 months after autologous chondrocyte implantation.

RESULTS

Group I patients showed significantly better results (< .01) in the International Cartilage Repair Society and Cincinnati scores than group II patients. Preoperative evaluation revealed no correlation between the sports activity levels and the clinical scores (P > .05). However, from the sixth month on, correlation was statistically significant, increasing from 6 to 18 months, and from 18 to 36 months postoperatively.

CONCLUSION

Physical training improves long-term results after autologous chondrocyte implantation of the knee and should be carried out for at least 2 years after surgery.

High-impact athletics after knee articular cartilage repair: a prospective evaluation of the microfracture technique

BACKGROUND

Knee articular cartilage injuries in athletes present a therapeutic challenge and have been identified as an important cause of permanent disability because of the high mechanical joint stresses in athletes.

PURPOSE

To determine whether microfracture treatment of knee articular cartilage injuries can return athletes to high-impact sports and to identify the factors that affect the ability to return to athletic activity.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Thirty-two athletes who regularly participated in high-impact, pivoting sports before articular cartilage injury were treated with microfracture for single articular cartilage lesions of the knee. Functional outcome was prospectively evaluated with a minimum 2-year follow-up by subjective rating, activity-based outcome scores, and the ability for postoperative participation in high-impact, pivoting sports.

RESULTS

At last follow-up, 66% of athletes reported good or excellent results. Activity of daily living, Marx activity rating scale, and Tegner activity scores increased significantly after microfracture. After an initial improvement, score decreases were observed in 47% of athletes. Forty-four percent of athletes were able to regularly participate in high-impact, pivoting sports, 57% of these at the preoperative level. Return to high-impact sports was significantly higher in athletes with age <40 years, lesion size <200 mm(2), preoperative symptoms <12 months, and no prior surgical intervention.

CONCLUSION

Microfracture is an effective first-line treatment to return young athletes with short symptomatic intervals and small articular cartilage lesions of the knee back to high-impact athletics.

The response of bone, articular cartilage and tendon to exercise in the horse

Horses can gallop within hours of birth, and may begin training for athletic competition while still growing. This review cites studies on the effects of exercise on bone, tendon and articular cartilage, as detected by clinical and research imaging techniques, tissue biochemical analysis and microscopy of various kinds. For bone, alterations in bone mineral content, mineral density and the morphology of the mineralized tissue are the most common end-points. Apparent bone density increases slightly after athletic training in the cortex, but substantially in the major load paths of the epiphyses and cuboidal bones, despite the lower material density of the new bone, which is deposited subperiosteally and on internal surfaces without prior osteoclastic resorption. With training of greater intensity, adaptive change is supervened by patho-anatomical change in the form of microdamage and frank lesions. In tendon, collagen fibril diameter distribution changes significantly during growth, but not after early training. The exact amount and type of protracted training that does cause reduction in mass average diameter (an early sign of progressive microdamage) have not been defined. Training is associated with an increase in the cross-sectional area of some tendons, possibly owing to slightly greater water content of non-collagenous or newly synthesized matrix. Early training may be associated with greater thickness of hyaline but not calcified articular cartilage, at least in some sites. The age at which adaptation of cartilage to biomechanical influences can occur may thus extend beyond very early life. However, cartilage appears to be the most susceptible of the three tissues to pathological alteration. The effect of training exercise on the anatomical or patho-anatomical features of connective tissue structures is affected by the timing, type and amount of natural or imposed exercise during growth and development which precedes the training.

Musculoskeletal disorders associated with obesity: a biomechanical perspective

Despite the multifactorial nature of musculoskeletal disease, obesity consistently emerges as a key and potentially modifiable risk factor in the onset and progression of musculoskeletal conditions of the hip, knee, ankle, foot and shoulder. To date, the majority of research has focused on the impact of obesity on bone and joint disorders, such as the risk of fracture and osteoarthritis. However, emerging evidence indicates that obesity may also have a profound effect on soft-tissue structures, such as tendon, fascia and cartilage. Although the mechanism remains unclear, the functional and structural limitations imposed by the additional loading of the locomotor system in obesity have been almost universally accepted to produce aberrant mechanics during locomotor tasks, thereby unduly raising stress within connective-tissue structures and the potential for musculoskeletal injury. While such mechanical theories abound, there is surprisingly little scientific evidence directly linking musculoskeletal injury to altered biomechanics in the obese. For the most part, even the biomechanical effects of obesity on the locomotor system remain unknown. Given the global increase in obesity and the rapid rise in musculoskeletal disorders, there is a need to determine the physical consequences of continued repetitive loading of major structures of the locomotor system in the obese and to establish how obesity may interact with other factors to potentially increase the risk of musculoskeletal disease.

Magnetic resonance imaging (MRI) of articular cartilage in knee osteoarthritis (OA): morphological assessment

OBJECTIVE

Magnetic resonance imaging (MRI) is a three-dimensional imaging technique with unparalleled ability to evaluate articular cartilage. This report reviews the current status of morphological assessment of cartilage with quantitative MRI (qMRI), and its relevance for identifying disease status, and monitoring progression and treatment response in knee osteoarthritis (OA).

METHOD

An international panel of experts in MRI of knee OA, with direct experience in the analysis of cartilage morphology with qMRI, reviewed the existing published and unpublished data on the subject, and debated the findings at the OMERACT-OARSI Workshop on Imaging technologies (December 2002, Bethesda, MA) with scientists and clinicians from academia, the pharmaceutical industry and the regulatory agencies. This report reviews (1) MRI pulse sequence considerations for morphological analysis of articular cartilage; (2) techniques for segmenting cartilage; (3) semi-quantitative scoring of cartilage status; and (4) technical validity (accuracy), precision (reproducibility) and sensitivity to change of quantitative measures of cartilage morphology.

RESULTS

Semi-quantitative scores of cartilage status have been shown to display adequate reliability, specificity and sensitivity, and to detect lesion progression at reasonable observation periods (1-2 years). Quantitative assessment of cartilage morphology (qMRI), with fat-suppressed gradient echo sequences, and appropriate image analysis techniques, displays high accuracy and adequate precision (e.g., root-mean-square standard deviation medial tibia=61 microl) for cross-sectional and longitudinal studies in OA patients. Longitudinal studies suggest that changes of cartilage volume of the order of -4% to -6% occur per annum in OA in most knee compartments (e.g., -90 microl in medial tibia). Annual changes in cartilage volume exceed the precision errors and appear to be associated with clinical symptoms as well as with time to knee arthroplasty.

CONCLUSIONS

MRI provides reliable and quantitative data on cartilage status throughout most compartments of the knee, with robust acquisition protocols for multi-center trials now being available. MRI of cartilage has tremendous potential for large scale epidemiological studies of OA progression, and for clinical trials of treatment response to structure modifying OA drugs.

Functional outcome of knee articular cartilage repair in adolescent athletes

BACKGROUND

Limited information exists about the treatment of full-thickness articular cartilage lesions of the knee in adolescent athletes.

PURPOSE

To evaluate the functional outcome and athletic activity after articular cartilage repair in the knees of adolescent athletes.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty adolescent athletes with full-thickness articular cartilage lesions of the knee were treated with autologous chondrocyte transplantation. Functional outcome was evaluated by subjective patient outcome rating, knee activity scores, and level of athletic participation.

RESULTS

At a mean of 47 months after autologous chondrocyte transplantation, 96% of adolescents reported good or excellent results with significant increases in postoperative Tegner activity scores and Lysholm scores. Ninety-six percent returned to high-impact sports and 60% to an athletic level equal or higher than that before knee injury. Return to preinjury sports correlated with shorter preoperative symptoms and a lower number of prior operations. All adolescents with preoperative symptoms < or =12 months returned to preinjury-level athletics, compared to 33% with preoperative intervals longer than 12 months.

CONCLUSION

Treatment of full-thickness articular injuries of the knee in adolescent athletes with autologous chondrocyte transplantation yields a high rate of functional success at a mean follow-up of 47 months. The rate of return to demanding athletic activities is higher in cases in which the preoperative duration of symptoms is 12 months or less.

Musculoskeletal responses of 2-year-old Thoroughbred horses to early training. 7. Bone and articular cartilage response in the carpus

AIM

To describe features of the morphology of the carpus, quantify the thickness of hyaline and calcified cartilage, and to describe the morphology and density of subchondral bone in the third carpal bone (C3) of young Thoroughbred horses in early training.

METHODS

C3 of seven 2-year-old horses in training and seven untrained horses matched for age, sex and breed were assessed by gross appearance, computed tomography, fine-structure radiography, image analysis of high-resolution photographs, and histology.

RESULTS

Macroscopic lesions in cartilage were few and mild, and not significantly different between groups. High bone mineral density (BMD), in some cases typical of cortical bone, was confined to the dorsal load path, and was significantly higher in trained than in untrained horses (p<0.01). In the most dorsoproximal aspect of the radial articular facet, apparently outside the dorsal load path, the BMD in both trained and untrained horses was significantly less than in other regions of interest (ROIs). Adaptive increase in density was associated with thickening of the (junctions of) trabeculae oriented proximo-distally. Hyaline cartilage was thicker (p<0.001) in the concavity of the radial articular facet than dorsal or palmar to it, and was thicker in the trained than untrained group (p=0.007). No such differences were detected in the thickness of articular calcified cartilage (ACC).

CONCLUSIONS

The rapid response of bone in C3 to relatively small amounts of high-speed exercise was confirmed. A previously unreported increase in thickness of hyaline cartilage was evident, perhaps indicating that this tissue may be more responsive than hitherto thought, at least to particular types of exercise at particular times. These changes occurred with little evidence of abnormality, and thus appeared to be adaptive to the exercise regimen. The model developed should be used for further definition of the exercise stimulus required to produce adaptive, protective changes in sites susceptible to athletic injury.

CLINICAL RELEVANCE

The data will serve as reference for use in subsequent imaging studies in which sophisticated aids such as magnetic resonance imaging (MRI) may be used to predict carpal lesions.

Toward imaging biomarkers for osteoarthritis

Many new therapeutic strategies have been and are being developed to correct, prevent, or slow the progression of osteoarthritis. Our ability to evaluate the efficacy of these techniques, or to determine the situations for which they might provide the most benefit, critically depends on diagnostic measures that can serve as proxies for the present or predicted state of the cartilage. Many of the magnetic resonance imaging techniques that have been emerging over the past decades appear promising in that they have shown technical validity in measuring the morphologic and molecular state of cartilage. With continued development and added insight from pilot clinical studies, these or related methods may soon be in customary use. These techniques are part of a paradigm shift where therapeutic strategies are developed hand-in-hand with diagnostic approaches-a shift that offers the promise of speeding development of effective therapies, and focusing their use in areas where they can be most successful.