Effects of in vivo exercise on ankle cartilage deformation and recovery in healthy volunteers: an experimental study

Ultrasound Measurement of Femoral Articular Cartilage Thickness Before and After Marathon Running

OBJECTIVE

The purpose of this study was to use ultrasonography to measure femoral articular cartilage thickness changes during marathon running, which could support MRI studies showing that deformation of knee cartilage during long-distance running is no greater than that for other weight-bearing activities.

MATERIALS AND METHODS

Participants included 38 marathon runners with no knee pain or history of knee injury, aged 18-39. Ultrasound images of the femoral articular cartilage were taken two hours before and immediately after the race. Femoral articular cartilage thickness was measured at both the medial and lateral femoral condyles.

RESULTS

The maximum change in femoral articular cartilage thickness, measured at the left outer lateral femoral condyle, was 6.94% (P=.006). All other femoral articular cartilage thickness changes were not significant.

CONCLUSION

A change in femoral articular cartilage thickness of 6.94% supports our hypothesis that long-distance running does not induce deformational changes greater than that of regular daily activities. This study using ultrasonography supports MRI evidence that knee cartilage tolerates marathon running well.

[18F]Sodium fluoride PET-MRI detects increased metabolic bone response to whole-joint loading stress in osteoarthritic knees

OBJECTIVE

Altered joint function is a hallmark of osteoarthritis (OA). Imaging techniques for joint function are limited, but [18F]sodium fluoride (NaF) PET-MRI may assess the acute joint response to loading stresses. [18F]NaF PET-MRI was used to study the acute joint response to exercise in OA knees, and compare relationships between regions of increased uptake after loading and structural OA progression two years later.

METHODS

In this prospective study, 10 participants with knee OA (59 ± 8 years; 8 female) were scanned twice consecutively using a PET-MR system and performed a one-legged squat exercise between scans. Changes in tracer uptake measures in 9 bone regions were compared between knees that did and did not exercise with a mixed-effects model. Areas of focally large changes in uptake between scans (ROIfocal, ΔSUVmax > 3) were identified and the presence of structural MRI features was noted. Five participants returned two years later to assess structural change on MRI.

RESULTS

There was a significant increase in [18F]NaF uptake in OA exercised knees (SUV P < 0.001, KiP = 0.002, K1P < 0.001) that differed by bone region.

CONCLUSION

There were regional differences in the acute bone metabolic response to exercise and areas of focally large changes in the metabolic bone response that might be representative of whole-joint dysfunction.

T2*-Mapping of Knee Cartilage in Response to Mechanical Loading in Alpine Skiing: A Feasibility Study

Purpose: This study intends to establish a study protocol for the quantitative magnetic resonance imaging (qMRI) measurement of biochemical changes in knee cartilage induced by mechanical stress during alpine skiing with the implementation of new spring-loaded ski binding. Methods: The MRI-knee-scans (T2*-mapping) of four skiers using a conventional and a spring-loaded ski binding system, alternately, were acquired before and after 1 h/4 h of exposure to alpine skiing. Intrachondral T2* analysis on 60 defined regions of interest in the femorotibial knee joint (FTJ) was conducted. Intra- and interobserver variability and relative changes in the cartilage T2* signal and thickness were calculated. Results: A relevant decrease in the T2* time after 4 h of alpine skiing could be detected at the majority of measurement times. After overnight recovery, the T2* time increased above baseline. Although, the total T2* signal in the superficial cartilage layers was higher than that in the lower ones, no differences between the layers in the T2* changes could be detected. The central and posterior cartilage zones of the FTJ responded with a stronger T2* alteration than the anterior zones. Conclusions: For the first time, a quantitative MRI study setting could be established to detect early knee cartilage reaction due to alpine skiing. Relevant changes in the T2* time and thus in the intrachondral collagen microstructure and the free water content were observed.

Talar-Cartilage Deformation and Spatiotemporal Gait Patterns in Individuals With and Those Without Chronic Ankle Instability

CONTEXT

Individuals with chronic ankle instability (CAI) present with alterations in the compositional structure of their talar articular cartilage. These alterations likely influence how the talar cartilage responds to the loading associated with activities of daily living, such as walking. Ultrasonography has emerged as an alternative imaging modality for assessing the amount of cartilage deformation in response to loading because it is clinically accessible and cost effective for routine measurements.

OBJECTIVES

To (1) compare talar-cartilage deformation in response to a standardized exercise protocol between those with and those without CAI and (2) examine the association between spatiotemporal walking gait parameters and cartilage deformation.

DESIGN

Case-control study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

A volunteer sample of 24 participants with self-reported CAI (age = 23.2 ± 3.9 years, body mass index [BMI] = 25.1 ± 3.7 kg/m2) and 24 uninjured controls (age = 24.3 ± 2.9 years, BMI = 22.9 ± 2.8 kg/m2).

MAIN OUTCOME MEASURE(S)

Spatiotemporal walking gait was first assessed from 5 self-selected trials using an electronic walkway with data sampled at 120 Hz. An 8- to 13-MHz linear-array ultrasound transducer placed transversely in line with the medial and lateral malleoli captured 3 images before and after a standardized loading protocol consisting of 30 single- and double-limb squats, 2-minute single-limb balance, and 10 single-legged drops from a 40-cm-height box.

RESULTS

After controlling for BMI, we found that the participants with CAI had greater deformation than the uninjured control participants (P = .034). No other between-groups differences were observed (P values > .05). No significant partial correlations were noted between talar-cartilage deformation and spatiotemporal gait parameters when controlling for BMI (P > .05).

CONCLUSIONS

Individuals with CAI had greater talar-cartilage deformation in response to a standardized exercise protocol than control individuals. The amount of talar-cartilage deformation was not associated with the spatiotemporal walking gait.

T1rho and T2 mapping of ankle cartilage of female and male ballet dancers

BACKGROUND

Since ballet dancers begin their training before skeletal maturity, accurate and non-invasive identification of cartilage diseases is clinically important. Angle-dependent analysis of T1rho and T2 sequences can be useful for quantification of the composition of cartilage.

PURPOSE

To investigate the angle-dependent T1rho and T2 profiles of ankle cartilage in non-dancers and dancers.

MATERIAL AND METHODS

Ten female non-dancers, ten female dancers, and 9 male dancers were evaluated using T1rho and T2 mapping sequences. Manual segmentation of talar and tibial cartilage on these images was performed by two radiologists. Inter- and intra-rater reliabilities were calculated using intraclass correlation coefficients (ICCs) and Bland-Altman analysis. Mean thickness and volume of cartilage were estimated. Angle-dependent relaxation time profiles of talar and tibial cartilage were created.

RESULTS

ICCs of the number of segmented pixels were poor to excellent. Bland-Altman plots indicated that differences were associated with segment sizes. Segmented cartilage on T1rho demonstrated larger thickness and volume than those on T2 in all populations. Male dancers showed larger cartilage thickness and volume than female dancers and non-dancers. Each cartilage demonstrated angular-dependent T1rho and T2 profiles. Minimal T1rho and T2 values were observed at approximately 180°-200°; higher values were seen at the angle closer to the magic angle. Minimal T2 value of talar cartilage of dancers was larger than that of non-dancers.

CONCLUSION

In this small cohort study, regional and sex variations of ankle cartilage T1rho and T2 values in dancers and non-dancers were demonstrated using an angle-dependent approach.

Comparison of Cartilage Mechanical Properties Measured During Creep and Recovery

The diagnosis of osteoarthritis (OA) currently depends on the presence of pain and radiographic imaging findings, which generally do not present until later stages of the disease when the condition is difficult to treat. Therefore, earlier detection of OA pathology is needed for improved disease management. Ex vivo cartilage studies indicate that changes in the mechanical function of cartilage occur as degeneration progresses during OA. Thus, measurement of the in vivo cartilage mechanical response may serve as an earlier indicator of OA pathology. Though mechanical characterization is classically performed during loading, the unloading (recovery) response of cartilage may also enable determination of mechanical response. Therefore, the purpose of this study was to validate the use of the recovery response for mechanical characterization of cartilage in a controlled, ex vivo environment. To do so, confined compression creep and recovery tests were conducted on cartilage explants (N = 10), and the resulting mechanical properties from both the creep and recovery phases were compared. No statistically significant differences were found in the mechanical properties between the two phases, reinforcing the hypothesis that unloading (recovery) may be a good surrogate for loading.

Plausible mechanisms of and techniques to assess ankle joint degeneration following lateral ankle sprains: a narrative review

Lateral ankle sprain (LAS) is the most common lower extremity musculoskeletal injury sustained during daily life and sport. The cascade of events that starts with ligamentous trauma leads to clinical manifestations such as recurrent sprains and giving way episodes, hallmark characteristics of chronic ankle instability (CAI). The sequelae of lateral ankle sprains and CAI appear to contribute to aberrant biomechanics. Combined, joint trauma and aberrant biomechanics appear to directly and/or indirectly play a role in talar cartilage degeneration. Up to 80% of all cases of ankle osteoarthritis (OA) are post-traumatic in nature and common etiologies for ankle post-traumatic osteoarthritis (PTOA) are histories of a single and recurrent ankle sprains. Despite known links between LAS, CAI, and PTOA and evidence demonstrating the burden of LAS and its sequelae, early pathoetiological changes of ankle PTOA and how they can be assessed are poorly understood. Therefore, the purpose of this paper is to review the plausible mechanistic links among LAS and its sequelae of CAI and PTOA as well as review non-surgical techniques that can quantify talar cartilage health. Understanding the pathway from ligamentous ankle injury to ankle PTOA is vital to developing theoretically sound therapeutic interventions aimed at slowing ankle PTOA progression. Further, directly assessing talar cartilage health non-surgically provides opportunities to quantify if current and novel intervention strategies are able to slow the progression of ankle PTOA.

Full biomechanical mapping of the ovine knee joint to determine creep-recovery, stiffness and thickness variation

BACKGROUND

Clinical cartilage repair strategies can be tested using the sheep model as suggest by the European Medicines Agency. To characterize variation within the joint a full biomechanical mapping is necessary. The aim of this study is to establish a loading model, to map regional differences within the knee and determine reference areas for area specific replacement techniques.

METHODS

A porous indenter was selected to evaluate 22 defined test locations (femoral condyles, tibia plateau, patella, femoral groove) on ovine knees (n = 7). A high-dynamic force-controlled micro creep and creep-recovery indentation test system applied five loading (0.11 MPa) and unloading (5.6 kPa) cycles for 60 s each and recorded creep-recovery. Needle indentation was used to measure cartilage thickness and calculate total strain.

FINDINGS

Steady state behaviour was observed from the third cycle and further evaluated. Little variation of stiffness in N/mm was found within the patella (4.3SD0.5) and femoral groove (8.1SD0.7) compared to larger variations in the femur (7.9SD2.0) and tibia (7.5SD3.2). Creep indentation showed values of 14.5%(SD2.7%) for the patella and 17.4%(SD3%) for the femoral grove opposed to 13.4%(SD4.3%) for the femoral condyles and 21.8%(SD6.6%) for the tibia plateau. Similar trends were observed analysing creep-recovery. Values were normalized to cartilage thickness which ranged between 0.36 mm and 1.14 mm.

INTERPRETATION

Our setup allows a reliable evaluation of zonal differences. Homogenous biomechanical behaviour is found within the patella and femoral groove whereas significant biomechanical variation within the femoral condyles and tibia plateau indicates the need for site-specific cartilage repair products.

T2* mapping of subtalar cartilage: Precision and association between anatomical variants and cartilage composition

Hindfoot arthritis is an important contributor to foot pain and physical disability. While the subtalar joint (STJ) is most frequently affected, anatomical variants such as facet configuration were suggested to further STJ cartilage deterioration. T2* mapping enables detection of ultra-structural cartilage change, particularly in thin cartilage layers, but its feasibility in the STJ has not yet been evaluated. The purpose of this study was to evaluate segmentation consistency and inter-scan short-term precision error of T2* mapping of talocalcaneal cartilage and to investigate the relationship between facet configuration and STJ T2* values. Using 3Tesla morphological magnetic resonance imaging, STJ configuration was categorized according to the degree of fusion between anterior, medial, or posterior facets. Subsequently, two repeats of multi-echo gradient recalled echo sequences were performed to obtain T2* maps with repositioning. Segmentation consistency of T2* values attained an ICC of 0.90 (95%CI 0.69-0.99). Precision errors comprised a coefficient of variation (CV) ranging 0.01-0.05, corresponding to a root mean square CV of 0.03-0.04. A 2-joint configuration type (i.e., fused anterior-medial facets) was significantly associated with a decrease in posterior facet T2* values (β = -0.6, p = 0.046). STJ T2* mapping is a reliable method requiring at least a 4% difference within people to enable detection of significant change. Anatomical variants in STJ configuration were associated with T2* values with the more stable 3-joint types exhibiting more favorable cartilage outcomes. Longer-term larger-scaled studies focusing on arthritis pathology are needed to further support the use of T2* mapping in hindfoot disease monitoring. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1969-1976, 2016.

An analysis of changes in in vivo cartilage thickness of the healthy ankle following dynamic activity

Abnormal cartilage loading after injury is believed to be an important factor leading to post-traumatic ankle osteoarthritis. Due to the viscoelastic behavior of cartilage, it is possible to measure localized cartilage strains from changes in thickness following dynamic activities. However, there are limited data characterizing in vivo cartilage mechanics under physiological loading conditions in the healthy ankle. Therefore, the objective of this study was to directly measure in vivo cartilage strains in the healthy ankle joint in response to a dynamic hopping exercise. Ten healthy subjects with no history of ankle injury underwent magnetic resonance imaging before and after a single-leg hopping exercise. Bony and articular cartilage surfaces were created from these images using solid modeling software. Pre-exercise and post-exercise models were then registered to each other, and site-specific cartilage strains (defined as the normalized changes in cartilage thickness) were calculated at grid points spanning the articular surfaces. The effects of both location and exercise on strain were tested using a two-way repeated measures analysis of variance. We did not detect any significant interaction effect between location and exercise for either tibial or talar cartilage. However, hopping resulted in significant decreases in tibial (p<0.05) and talar (p<0.05) cartilage thicknesses, corresponding to strains of 3% and 2%, respectively. Additionally, pre-exercise cartilage thickness varied significantly by location in the talus (p<0.05), but not in the tibia. These strain data may provide important baseline information for future studies investigating altered biomechanics in those at high risk for the development of post-traumatic ankle osteoarthritis.

In vivo deformation of thin cartilage layers: Feasibility and applicability of T2* mapping

The objectives of this study were as follows: (i) to assess segmentation consistency and scan precision of T2* mapping of human tibio-talar cartilage, and (ii) to monitor changes in T2* relaxation times of ankle cartilage immediately following a clinically relevant in vivo exercise and during recovery. Using multi-echo gradient recalled echo sequences, averaged T2* values were calculated for tibio-talar cartilage layers in 10 healthy volunteers. Segmentation consistency and scan precision were determined from two repeated segmentations and two repeated acquisitions with repositioning, respectively. Subsequently, acute in vivo cartilage loading responses were monitored by calculating averaged tibio-talar T2* values at rest, immediately after (i.e., deformation) and at 15 min (i.e., recovery) following a 30-repetition knee bending exercise. Precision errors attained 4-6% with excellent segmentation consistency point estimates (i.e., intra-rater ICC of 0.95) and acceptable limits of confidence. At deformation, T2* values were increased in both layers [+16.1 (10.7)%, p = 0.004 and +17.3 (15.3)%, p = 0.023, for the talus and tibia, respectively] whereas during recovery no significant changes could be established when comparing to baseline [talar cartilage: +5.2 (8.2)%, p = 0.26 and tibial cartilage: +6.6 (10.4)%, p = 0.23]. T2* mapping is a viable method to monitor deformational behavior in thin cartilage layers such as ankle cartilage. Longitudinal changes in T2* can be reliably appraised and require at least 4-6% differences to ascertain statistical significance. The ability to detect considerable change even after non-strenuous loading events, endorses T2* mapping as an innovative method to evaluate the effects of therapeutic exercise on thin cartilage layers. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:771-778, 2016.

Topographical and sex variations in the T2 relaxation times of articular cartilage in the ankle joints of healthy young adults using 3.0T MRI

PURPOSE

To prospectively evaluate topographical and sex variations in the T2 relaxation values of tibiotalar cartilage (TTC) of healthy young adults.

MATERIALS AND METHODS

Sagittal 8-echo multiecho spin-echo T2 maps of TTC were acquired using a 3.0T MR in 25 male and 25 female healthy young adult participants. Quantitative measurements of T2 values in tibial cartilage (TBC) and talar cartilage (TLC) were obtained from three zones (anterior zone, AZ; middle zone, MZ; and posterior zone, PZ) and from four compartments (medial compartment, MC; midmedial compartment, MMC; midlateral compartment, MLC; and lateral compartment, LC) of TBC and TLC in the sagittal plane.

RESULTS

The T2 values of AZ (for TBC, 29.31 msec; for TLC, 35.81 msec) and MZ (for TBC, 28.56 msec; for TLC, 36.12 msec) in males were significantly higher than those in females (for AZ of TBC, 26.99 msec; for AZ of TLC, 33.56 msec; for MZ of TBC, 25.88 msec; for MZ of TLC, 31.85 msec) (for TBC, AZ, P = 0.009, MZ, P = 0.002; for TLC, AZ, P = 0.047, MZ, P = 0.001). Except for MMC and MLC of TBC (MMC, P = 0.02, MLC, P = 0.03), TTC T2 values did not differ significantly between these compartment in either group (for TBC, MC, P = 0.27, LC, P = 0.37; for TLC, MC, P = 0.26, MMC, P = 0.08, MLC, P = 0.30, LC, P = 0.10).

CONCLUSION

We found significant sex and topographic variations among TTC T2 values of healthy young adults. Acknowledgment of the significant topographical and sex variations in cartilage T2 values may minimize misinterpretation of ankle joint TTC T2 mapping data.

Biochemical cartilage alteration and unexpected signal recovery in T2* mapping observed in ankle joints with mobile MRI during a transcontinental multistage footrace over 4486 km

OBJECTIVE

The effect of ultra-long distance running on the ankle cartilage with regard to biochemical changes, thickness and lesions is examined in the progress of a transcontinental ultramarathon over 4486 km.

METHOD

In an observational field study, repeated follow-up scanning of 22 participants of the TransEurope FootRace (TEFR) with a 1.5 T MRI mounted on a mobile unit was performed. For quantitative biochemical and structural evaluation of cartilage a fast low angle shot (FLASH) T2* weighted gradient-echo (GRE)-, a turbo-inversion-recovery-magnitude (TIRM)- and a fat-saturated proton density (PD)-weighted sequence were utilized. Statistical analysis of cartilage T2* and thickness changes was obtained on the 13 finishers (12 male, mean age 45.4 years, BMI 23.5 kg/m²). None of the nine non-finisher (eight male, mean age 53.8 years, BMI 23.4 kg/m²) stopped the race due to ankle problems.

RESULTS

From a mean of 17.0 ms for tibial plafond and 18.0 ms for talar dome articular cartilage at baseline, nearly all observed regions of interest (ROIs) of the ankle joint cartilage showed a significant T2*-signal increase (25.6% in mean), with standard error ranging from 19% to 33% within the first 2500 km of the ultra-marathon. This initial signal behavior was followed by a signal decrease. This signal recovery (30.6% of initial increase) showed a large effect size. No significant morphological or cartilage thickness changes (at baseline 2.9 mm) were observed.

CONCLUSION

After initial T2*-increase during the first 2000-2500 km, a subsequent T2*-decrease indicates the ability of the normal cartilage matrix to partially regenerate under ongoing multistage ultramarathon burden in the ankle joints.

Acute cartilage loading responses after an in vivo squatting exercise in people with doubtful to mild knee osteoarthritis: a case-control study

BACKGROUND

The effects of exercise on osteoarthritic cartilage remain elusive.

OBJECTIVE

The objective of this study was to investigate the effect of dynamic in vivo squatting exercise on the magnitude and spatial pattern of acute cartilage responses in people with tibiofemoral osteoarthritis (ie, Kellgren-Lawrence grades 1 and 2).

DESIGN

This investigation was a case-control study.

METHODS

Eighteen people with radiographic signs of doubtful to mild medial tibiofemoral osteoarthritis were compared with 18 people who were middle-aged and healthy (controls). Three-dimensional magnetic resonance imaging was used to monitor deformation and recovery on the basis of 3-dimensional cartilage volume calculations (ie, total volume and volumes in anterior, central, and posterior subregions) before and after a 30-repetition squatting exercise. Three-dimensional volumes were estimated after semiautomatic segmentation and were calculated at 4 time points (1 before and 3 after scans). Scans obtained after the exercise were separated by 15-minute intervals.

RESULTS

In both groups, significant deformation was noted in the medial compartment (-3.4% for the femur and -3.2% for the tibia in people with osteoarthritis versus -2.8% for the femur and -3.8% for the tibia in people in the control group). People with osteoarthritis had significant deformation in the lateral femur (-3.9%) and a tendency toward significant deformation in the lateral tibia (-3.1%). From 15 minutes after exercise cessation onward, volume changes were no longer significantly different from the baseline. At all time points, no significant between-group differences were revealed for volume changes. People with osteoarthritis showed a tendency toward slower recovery preceded by larger deformations in entire cartilage plates and subregions. Spatial subregional deformation patterns were similar between groups.

LIMITATIONS

Generalizability is limited to people with doubtful to mild osteoarthritis and low levels of pain.

CONCLUSIONS

Tibiofemoral cartilage deformation appeared similar in magnitude and spatial pattern in people who were middle-aged and either had or did not have tibiofemoral osteoarthritis (ie, Kellgren-Lawrence grades 1 and 2). Restoration of volumes required a 15-minute recovery, especially in the presence of osteoarthritic cartilage degeneration.

Cartilage status in relation to return to sports after anterior cruciate ligament reconstruction

BACKGROUND

Osteoarthritis after anterior cruciate ligament (ACL) reconstruction receives much attention in orthopaedic science. Anterior cruciate ligament reconstruction is related to increased joint fluid volumes, bone marrow edema, and cartilage biochemical and morphological changes believed to cause fragile joint conditions. These joint conditions may not be able to adequately counter the imposed loads during sports.

HYPOTHESIS

At 6 months after surgery, knee cartilage displays inferior quality in ACL-reconstructed knees when compared with controls. This inferior quality is influenced by the time to return to sports and/or by the time to surgery.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Fifteen patients treated with isolated ACL reconstruction were compared with 15 matched controls. In all participants, a 3-T magnetic resonance imaging cartilage evaluation was performed entailing quantitative morphological characteristics (3-dimensional volume/thickness), biochemical composition (T2/T2* mapping), and function (after a 30-minute run: in vivo deformation including recovery). Nonparametric statistics were executed reporting median (95% CI).

RESULTS

No volume and thickness between-group differences existed. In patients, medial femur (FM) T2 was higher (45.44 ms [95% CI, 40.64-51.49] vs 37.19 ms [95% CI, 34.67-40.39]; P = .028), whereas T2* was lower in the FM (21.81 ms [95% CI, 19.89-22.74] vs 24.29 ms [95% CI, 22.70-26.26]; P = .004), medial tibia (TM) (13.81 ms [95% CI, 10.26-16.78] vs 17.98 ms [95% CI, 15.95-18.90]; P = .016), and lateral tibia (TL) (14.69 ms [95% CI, 11.71-16.72] vs 18.62 ms [95% CI, 17.85-22.04]; P < .001). Patients showed diminished recovery at 30 minutes after a 30-minute run in the FM (-1.60% [95% CI, -4.82 to -0.13] vs 0.01% [95% CI, -0.34 to 1.23]; P = .040) and at 30 (-3.76% [95% CI, -9.29 to -1.78] vs 0.04% [95% CI, -1.52 to -0.72]; P = .004) and 45 minutes after exercise (-1.86% [95% CI, -4.66 to -0.40] vs 0.43% [95% CI, -0.91 to 0.77]; P = .024) in the TL. Eight patients returned to sports at 6 months or earlier. Return before 5 months (3/8 patients) was associated with increased cartilage thickness (in TM, TL, and lateral femur [FL]), deformation (in FL), and delayed recovery after running (in FL and FM). Median surgical delay was 10 weeks (range, 5-17 weeks). Surgery within 10 weeks (9/15 patients) was also associated with delayed cartilage recovery (in FL and FM). For the other parameters, no significant relationships could be established for either return to sports or surgical delay.

CONCLUSION

At 6 months after surgery, cartilage in patients with ACL reconstruction shows diminished quality and in vivo resiliency compared with controls. Caution is advised in an early return to sports especially when dealing with patients who received prompt surgery. Possibly, high impacts on this qualitatively diminished cartilage might play a role in the development of osteoarthritis in ACL reconstruction. Replication in larger samples and follow-up are warranted.

Microfracture for osteochondral lesions of the talus: a systematic review of reporting of outcome data

BACKGROUND

Microfracture is recognized as a primary treatment strategy for osteochondral lesions of the talus up to 15 mm in size. The ability of fibrocartilage to withstand the mechanical loading of the joint over time is unknown.

PURPOSE

The purpose of this study was to systematically review studies of microfracture for OLT and descriptively analyze the outcome data reported to determine whether it is consistent from one study to another and able to be pooled for systematic review.

METHODS

A systematic electronic search was performed using the MEDLINE and EMBASE databases. Studies that were published between January 1966 and June 2011 were included in the review. Only studies that reported data specifically on microfracture for treatment of osteochondral lesions of the talus and written in English were included in this review.

RESULTS

Twenty-four studies were included in this systematic review. The categories of general demographics and study design were generally well reported (each over 80% of studies). Patient history and patient-reported outcome data were reported less (55%-66%). Clinical variables (48%) and imaging data (39%) were the least reported in studies.

CONCLUSION

There were gross inconsistencies and an underreporting of data between studies such that pooling was deemed impossible. A concerted effort must be made by investigators to ensure that there is adequate reporting of data in studies of microfracture treatment for OLT. A set of guidelines to assist surgeons in reporting data may be useful for future research.

Diurnal variations in articular cartilage thickness and strain in the human knee

Due to the biphasic viscoelastic nature of cartilage, joint loading may result in deformations that require times on the order of hours to fully recover. Thus, cartilaginous tissues may exhibit cumulative strain over the course of each day. The goal of this study was to assess the magnitude and spatial distribution of strain in the articular cartilage of the knee with daily activity. Magnetic resonance (MR) images of 10 asymptomatic subjects (six males and four females) with mean age of 29 years were obtained at 8:00 AM and 4:00 PM on the same day using a 3T magnet. These images were used to create 3D models of the femur, tibia, and patella from which cartilage thickness distributions were quantified. Cartilage thickness generally decreased from AM to PM in all areas except the patellofemoral groove and was associated with significant compressive strains in the medial condyle and tibial plateau. From AM to PM, cartilage of the medial tibial plateau exhibited a compressive strain of -5.1±1.0% (mean±SEM) averaged over all locations, while strains in the lateral plateau were slightly lower (-3.1±0.6%). Femoral cartilage showed an average strain of -1.9±0.6%. The findings of this study show that human knee cartilage undergoes diurnal changes in strain that vary with site in the joint. Since abnormal joint loading can be detrimental to cartilage homeostasis, these data provide a baseline for future studies investigating the effects of altered biomechanics on diurnal cartilage strains and cartilage physiology.