Associations of pain sensitivity and conditioned pain modulation with physical activity: findings from the Multicenter Osteoarthritis Study (MOST).

OBJECTIVE: Individuals with chronic pain due to knee osteoarthritis (OA) are insufficiently physically active, and alterations of facilitatory and inhibitory nociceptive signaling are common in this population. Our objective was to examine the association of these alterations in nociceptive signaling with objective accelerometer-based measures of physical activity in a large observational cohort. DESIGN: We used data from the Multicenter Osteoarthritis Study. Measures of peripheral and central pain sensitivity included pressure pain threshold at the knee and mechanical temporal summation at the wrist, respectively. The presence of descending pain inhibition was assessed by conditioned pain modulation (CPM). Physical activity was quantitatively assessed over 7 days using a lower back-worn activity monitor. Summary metrics included steps/day, activity intensity, and sedentary time. Linear regression analyses were used to evaluate the association of pain sensitivity and the presence of descending pain inhibition with physical activity measures. RESULTS: Data from 1873 participants was analyzed (55.9% female, age = 62.8 ± 10.0 years). People having greater peripheral and central sensitivity showed lower step counts. CPM was not significantly related to any of the physical activity measures, and none of the exposures were significantly related to sedentary time. CONCLUSIONS: In this cohort, greater peripheral and central sensitivity were associated with reduced levels of objectively-assessed daily step counts. Further research may investigate ways to modify or treat heightened pain sensitivity as a means to increase physical activity in older adults with knee OA.

Obesity is related to incidence of patellofemoral osteoarthritis: the Cohort Hip and Cohort Knee (CHECK) study.

To determine the longitudinal association of baseline body mass index and change in body mass index over 8 years to incident of patellofemoral osteoarthritis at the 8-year follow-up. A sample of 528 women and men, aged 45-65 years, with knee complaints and without radiographic evidence of patellofemoral and tibiofemoral osteoarthritis at baseline, were selected from the Cohort Hip and Cohort Knee cohort. Incidence of patellofemoral osteoarthritis was defined as presence of radiographic patellofemoral osteoarthritis (with or without tibiofemoral osteoarthritis) at the 8-year follow-up. Baseline body mass index data were categorized into normal, overweight, and obese weight-categories. Logistic regression analyses, adjusted for age and sex, were conducted to determine the association of baseline body mass index and change in body mass index to patellofemoral osteoarthritis incidence 8 years later. Obesity was associated with greater odds of radiographic patellofemoral osteoarthritis incident (odds ratio: 1.8 [95% CI 1.1, 3.1]) 8 years later. There were no significant associations observed between body mass index change over 8 years and incidence of radiographic patellofemoral osteoarthritis in overweight and obese individuals. Obesity is associated with increased odds of developing radiographic patellofemoral osteoarthritis 8 years later.

Prevalence of knee osteoarthritis features on magnetic resonance imaging in asymptomatic uninjured adults: a systematic review and meta-analysis.

BACKGROUND: Knee MRI is increasingly used to inform clinical management. Features associated with osteoarthritis are often present in asymptomatic uninjured knees; however, the estimated prevalence varies substantially between studies. We performed a systematic review with meta-analysis to provide summary estimates of the prevalence of MRI features of osteoarthritis in asymptomatic uninjured knees. METHODS: We searched six electronic databases for studies reporting MRI osteoarthritis feature prevalence (ie, cartilage defects, meniscal tears, bone marrow lesions and osteophytes) in asymptomatic uninjured knees. Summary estimates were calculated using random-effects meta-analysis (and stratified by mean age: <40 vs ≥40 years). Meta-regression explored heterogeneity. RESULTS: We included 63 studies (5397 knees of 4751 adults). The overall pooled prevalence of cartilage defects was 24% (95% CI 15% to 34%) and meniscal tears was 10% (7% to 13%), with significantly higher prevalence with age: cartilage defect <40 years 11% (6%to 17%) and ≥40 years 43% (29% to 57%); meniscal tear <40 years 4% (2% to 7%) and ≥40 years 19% (13% to 26%). The overall pooled estimate of bone marrow lesions and osteophytes was 18% (12% to 24%) and 25% (14% to 38%), respectively, with prevalence of osteophytes (but not bone marrow lesions) increasing with age. Significant associations were found between prevalence estimates and MRI sequences used, physical activity, radiographic osteoarthritis and risk of bias. CONCLUSIONS: Summary estimates of MRI osteoarthritis feature prevalence among asymptomatic uninjured knees were 4%-14% in adults aged <40 years to 19%-43% in adults ≥40 years. These imaging findings should be interpreted in the context of clinical presentations and considered in clinical decision-making.

Relationship of Trochlear Morphology and Patellofemoral Joint Alignment to Superolateral Hoffa Fat Pad Edema on MR Images in Individuals with or at Risk for Osteoarthritis of the Knee: The MOST Study.

Purpose To determine the relationship of patellofemoral joint alignment and trochlear morphology to superolateral Hoffa fat pad (SHFP) edema on magnetic resonance (MR) images in older adults with or at risk for osteoarthritis of the knee. Materials and Methods Institutional review board approval and written informed consent were obtained from all subjects. The Multicenter Osteoarthritis Study is a prospective cohort study of older adults with or at risk for osteoarthritis of the knee. Subjects were recruited from Birmingham, Alabama, and Iowa City, Iowa. In this cross-sectional study, patellofemoral joint alignment (bisect offset, patellar tilt angle, and Insall-Salvati ratio), trochlear morphology (sulcus angle, lateral and medial trochlear inclination, and trochlear angle) and SHFP edema were assessed on MR images of the knee. Measures of alignment and morphology were divided into quartiles, and SHFP was determined to be present or absent. Separate logistic regression models were used to determine the relationship of each measure of alignment and morphology to the presence of SHFP edema, with adjustments for age, sex, and body mass index. Results SHFP edema was present in 152 (13.4%) of the 1134 knees that were included. When compared with knees with measurements in the lowest quartile, knees with measurements in the highest quartile for trochlear angle, bisect offset, and Insall-Salvati ratios were 1.6 (95% confidence interval [CI]: 1.0, 2.6), 2.3 (95% CI: 1.3, 4.0), and 8.9 (95% CI: 4.7, 16.9) times more likely to show SHFP edema, respectively. No relationship was found between other measures and SHFP edema. Conclusion A more anterior trochlear facet, a more laterally displaced patella, and knees with patella alta were significantly associated with SHFP edema on MR images in subjects with or at risk for osteoarthritis of the knee. © RSNA, 2017.

The prevalence of radiographic and MRI-defined patellofemoral osteoarthritis and structural pathology: a systematic review and meta-analysis.

BACKGROUND: Patellofemoral osteoarthritis (PF OA) is more prevalent than previously thought and contributes to patient's suffering from knee OA. Synthesis of prevalence data can provide estimates of the burden of PF OA. OBJECTIVE: This study aims to conduct a systematic review and meta-analysis on the prevalence of PF OA and structural damage based on radiography and MRI studies in different populations. METHODS: We searched six electronic databases and reference lists of relevant cross-sectional and observational studies reporting the prevalence of PF OA. Two independent reviewers appraised methodological quality. Where possible, data were pooled using the following categories: radiography and MRI studies. RESULTS: Eighty-five studies that reported the prevalence of patellofemoral OA and structural damage were included in this systematic review. Meta-analysis revealed a high prevalence of radiographic PF OA in knee pain or symptomatic knee OA (43%), radiographic knee OA or at risk of developing OA (48%) and radiographic and symptomatic knee OA (57%) cohorts. The MRI-defined structural PF damage in knee pain or symptomatic population was 32% and 52% based on bone marrow lesion and cartilage defect, respectively. CONCLUSION: One half of people with knee pain or radiographic OA have patellofemoral involvement. Prevalence of MRI findings was high in symptomatic and asymptomatic population. These pooled data and the variability found can provide evidence for future research addressing risk factors and treatments for PF OA. TRIAL REGISTRATION NUMBER: PROSPERO systematic review protocol (CRD42016035649).

Gait Alterations and Association With Worsening Knee Pain and Physical Function: A Machine Learning Approach With Wearable Sensors in the Multicenter Osteoarthritis Study.

OBJECTIVE: The objective of this study was to identify gait alterations related to worsening knee pain and worsening physical function, using machine learning approaches applied to wearable sensor-derived data from a large observational cohort. METHODS: Participants in the Multicenter Osteoarthritis Study (MOST) completed a 20-m walk test wearing inertial sensors on their lower back and ankles. Parameters describing spatiotemporal features of gait were extracted from these data. We used an ensemble machine learning technique ("super learning") to optimally discriminate between those with and without worsening physical function and, separately, those with and without worsening pain over two years. We then used log-binomial regression to evaluate associations of the top 10 influential variables selected with super learning with each outcome. We also assessed whether the relation of altered gait with worsening function was mediated by changes in pain. RESULTS: Of 2,324 participants, 29% and 24% had worsening knee pain and function over two years, respectively. From the super learner, several gait parameters were found to be influential for worsening pain and for worsening function. After adjusting for confounders, greater gait asymmetry, longer average step length, and lower dominant frequency were associated with worsening pain, and lower cadence was associated with worsening function. Worsening pain partially mediated the association of cadence with function. CONCLUSION: We identified gait alterations associated with worsening knee pain and those associated with worsening physical function. These alterations could be assessed with wearable sensors in clinical settings. Further research should determine whether they might be therapeutic targets to prevent worsening pain and worsening function.

Association between measures of patella height, morphologic features of the trochlea, and patellofemoral joint alignment: the MOST study.

BACKGROUND: Patellofemoral joint (PFJ) malalignment (lateral patella displacement and tilt) has been proposed as a cause of patellofemoral pain. Patella height and/or the morphologic features of the femoral trochlea may predispose one to patella malalignment. QUESTIONS/PURPOSES: The purposes of our study were to assess the associations among patella height, morphologic features of the trochlea, and measures of PFJ alignment and to determine which measures of patella height and morphologic features of the trochlea were the best predictors of PFJ alignment. METHODS: Measures of patella height (Insall-Salvati ratio and modified Insall-Salvati ratio), morphologic features of the trochlea (sulcus angle, trochlear angle, lateral trochlear inclination, medial trochlear inclination), and PFJ alignment (bisect offset and patella tilt angle) were assessed in 566 knees from the Multicenter Osteoarthritis Study. RESULTS: Bisect offset was correlated with the Insall-Salvati ratio (r = 0.25) and lateral trochlear inclination (r = -0.38). Patella tilt angle correlated with the trochlear angle (-0.27) and lateral trochlear inclination (-0.32). Linear regression models including the Insall-Salvati ratio and lateral trochlear inclination explained 20% and 11% of the variance in bisect offset and patella tilt angle, respectively. CONCLUSIONS: Of the variables measured in the current study, the Insall-Salvati ratio and lateral trochlear inclination were the best predictors of lateral patella displacement and lateral tilt. This knowledge will aid clinicians in the identification of anatomic risk factors for PFJ malalignment and/or PFJ dysfunction.

Association of tibial acceleration during walking to pain and impact loading in adults with knee osteoarthritis.

BACKGROUND: Higher impact loading during walking is implicated in the pathogenesis of knee osteoarthritis. Accelerometry enables the measurement of peak tibial acceleration outside the laboratory. We characterized the relations of peak tibial acceleration to knee pain and impact loading during walking in adults with knee osteoarthritis. METHODS: Adults with knee osteoarthritis reported knee pain then walked at a self-selected speed on an instrumented treadmill for 3 min with an ankle-worn inertial measurement unit. Ground reaction forces and tibial acceleration data were sampled for 1 min. Vertical impact peaks, and average and peak instantaneous load rates were determined and averaged across 10 steps. Peak tibial acceleration was extracted for all steps and averaged. Pearson's correlations and multiple linear regression analyses assessed the relation of peak tibial acceleration to pain and impact loading metrics, independently and after controlling for gait speed and pain. FINDINGS: Higher peak tibial acceleration was associated with worse knee pain (r = 0.39; p = 0.01), and higher vertical average (r = 0.40; p = 0.01) and instantaneous (r = 0.46; p = 0.004) load rates. After adjusting for gait speed and pain, peak tibial acceleration was a significant predictor of vertical average (R2 = 0.33; p = 0.003) and instantaneous (R2 = 0.28; p = 0.02) load rates, but not strongly associated with vertical impact peak. INTERPRETATIONS: Peak tibial acceleration during walking is associated with knee pain and vertical load rates in those with knee osteoarthritis. Clinicians can easily access measures of peak tibial acceleration with wearable sensors equipped with accelerometers. Future work should determine the feasibility of improving patient outcomes by using peak tibial acceleration to inform clinical management.

Sitting may increase risk for radiographic incidence and progression of knee osteoarthritis over 2 years: Data from a large cohort study.

OBJECTIVES: To examine the association of leisure-time sitting with radiographic incidence and progression of knee osteoarthritis (OA) over 2 years, and to determine whether worktime sitting modifies this association. METHODS: We included adults with or at high risk for knee OA who enroled in the Osteoarthritis Initiative (OAI). Participants reported leisure-time sitting (≤4 vs. >4 h/day) and worktime sitting (frequent vs. infrequent) at enrolment, and had bilateral knee radiographs at enrolment and 2 years later. Our outcome, radiographic knee OA incidence/progression (yes/no), was defined as any increase in Kellgren-Lawrence grade over 2 years. We examined the association of leisure-time sitting (≤4 vs. >4 h/day) with risk of radiographic knee OA incidence/progression using binary linear regression, adjusting for potential confounders. We stratified by worktime sitting (frequent vs. infrequent) and repeated our analysis. RESULTS: We included 4254 adults (mean age 61 years; 58% women; mean body mass index 29 kg/m2 ) who contributed a total of 8127 knees. Adults with >4 h/day of leisure-time sitting had 25% higher risk (adjusted risk ratio [RR] 1.25, 95% confidence interval [95% CI] 1.08-1.50) for radiographic knee OA incidence/progression compared with adults with ≤4 h/day of leisure-time sitting (referent group). Importantly, this association was intensified (RR 1.60, 95% CI 1.19-2.33) among adults with frequent worktime sitting, but was attenuated (RR 1.11, 95% CI 0.89-1.39) among adults with infrequent worktime sitting. CONCLUSIONS: Higher leisure-time sitting (>4 h/day) may be associated with greater risk for radiographic knee OA incidence/progression over 2 years. Furthermore, this association was intensified among adults who also reported frequent worktime sitting.

Association of mechanical temporal summation of pain with muscle co-contraction during walking in people with knee osteoarthritis.

BACKGROUND: People with knee osteoarthritis walk with excessive muscle co-contraction that can accelerate disease progression. Central pain sensitization is common in people with knee osteoarthritis and may be related to walking patterns. The objective of this study was to examine the relation of central pain sensitization with muscle co-contraction during walking in people with knee osteoarthritis. METHODS: This study reports secondary analysis from baseline data of two clinical trials (n = 90 participants with knee osteoarthritis). The presence of central pain sensitization was measured by mechanical temporal summation at the patella and the wrist. Quadriceps and hamstrings activation was assessed using surface electromyography during walking at self-selected and fast paces. Muscle co-contraction indices for vastus medialis-medial hamstrings and vastus lateralis-lateral hamstrings muscle pairs were calculated during stance phases. Co-contraction outcomes were compared between people with and without mechanical temporal summation at each site, adjusting for age, sex, and body mass index. FINDINGS: People with mechanical temporal summation at the knee had greater vastus lateralis-lateral hamstrings co-contraction while walking at a fast pace (P = 0.04). None of the other differences was statistically significant, but the overall trends and effect sizes indicated greater co-contraction in people with temporal summation at the knee irrespective of gait phase, walking speed, or muscle pairs. INTERPRETATION: Central pain sensitization, assessed as mechanical temporal summation at the knee, is related to greater knee muscle co-contraction during fast walking in people with knee osteoarthritis. Thus, mitigating central sensitization may be an interventional target to reduce muscle co-contraction for people with knee osteoarthritis.

Relation of Temporal Asymmetry During Walking to Two-Year Knee Pain Outcomes in Those With Mild-to-Moderate Unilateral Knee Pain: An Exploratory Analysis From the Multicenter Osteoarthritis Study.

OBJECTIVE: We aimed to explore the cross-sectional relation of unilateral knee pain severity and temporal asymmetry during walking and to determine relations of temporal asymmetry during walking to 2-year changes in ipsilateral and contralateral knee pain in those with mild-to-moderate unilateral knee pain. METHODS: The Multicenter Osteoarthritis Study is a prospective cohort study of adults with or at risk for knee osteoarthritis. The current study included participants with unilateral knee pain. Gait was assessed during self-selected and fast walking at baseline. Knee pain was assessed at baseline and 2 years. We calculated limb symmetry indices (LSIs; nonpainful limb/painful limb × 100) for stance, single-limb support time, and double-limb support time, then examined their relations to unilateral knee pain severity, incident contralateral knee pain, and persistent ipsilateral knee pain. RESULTS: Unilateral knee pain severity was not associated with temporal asymmetry during self-selected or fast walking. At 2 years, 17.1% of participants had incident contralateral knee pain and 51.4% had persistent ipsilateral knee pain. For self-selected walking, greater LSIs (i.e., longer time on the nonpainful limb) for stance and single-limb support time were associated with decreased odds of incident contralateral knee pain. Measures of temporal asymmetry were not associated with persistent ipsilateral knee pain, except for single-limb support time during fast walking. CONCLUSION: For those with unilateral knee pain, temporal asymmetry during walking is not associated with pain severity. However, select measures of stance and single-limb support time during self-selected and fast walking relate to longitudinal knee pain outcomes.

Hip Abductor Weakness and Its Association With New or Worsened Knee Pain: Data From the Multicenter Osteoarthritis Study.

OBJECTIVE: Hip abductors, important for controlling pelvic and femoral orientation during gait, may affect knee pain. Our objective was to evaluate the relation of hip abductor strength to worsened or new-onset frequent knee pain. Given previously noted associations of knee extensor strength with osteoarthritis in women, we performed sex-specific analyses. METHODS: We used data from the Multicenter Osteoarthritis study. Hip abductor and knee extensor strength was measured. Knee pain was assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire and a question about frequent knee pain at baseline (144-month visit), and 8, 16, and 24 months thereafter. Knee pain outcomes were worsened knee pain (2-point increase in WOMAC pain) and incident frequent knee pain (answering yes to the frequent knee pain question among those without frequent knee pain at baseline). Leg-specific analyses tested hip abductor strength as a risk factor for worsened and new frequent knee pain, adjusting for potential covariates. Additionally, we stratified by knee extensor strength (high versus low). RESULTS: Among women, compared to the highest quartile of hip abductor strength, the lowest quartile had 1.7 (95% confidence interval [95% CI] 1.1-2.6) times the odds of worsened knee pain; significant associations were limited to women with high knee extensor strength (odds ratio 2.0 [95% CI 1.1-3.5]). We found no relation of abductor strength to worsening knee pain in men or with incident frequent knee pain in men or women. CONCLUSION: Hip abductor weakness was associated with worsening knee pain in women with strong knee extensors, but not with incident frequent knee pain in men or women. Knee extensor strength may be necessary, but not sufficient, to prevent pain worsening.

Breaking the Law of Valgus: the surprising and unexplained prevalence of medial patellofemoral cartilage damage.

OBJECTIVES: To compare the prevalence of medial and lateral patellofemoral (PF) cartilage damage in three large osteoarthritis (OA) studies and determine the relationship of this damage to varus, neutral and valgus knee alignment. METHODS: In the Boston OA of the Knee, Framingham OA and Multicenter OA studies, MRIs were read for cartilage morphology at the medial and lateral patella and trochlea femoris using Whole-Organ MRI Scores (WORMS). WORMS scores ≥2 (any cartilage defect), ≥3 (areas of partial thickness loss), ≥4 (diffuse partial thickness loss) and ≥5 (extensive full thickness loss) were all variously considered as thresholds to identify damage that may indicate OA. Full-limb radiographs were measured for mechanical alignment, and varus (<-2°), neutral (-2° to 2°) and valgus (>2°) knees were identified. RESULTS: The prevalence of medial PF cartilage damage exceeded that of lateral damage in all three studies and according to nearly every threshold. Only among severely involved knees (WORMS ≥4 or ≥5) did the prevalence of lateral PF cartilage damage approximate that of medial damage. The high prevalence of medial PF damage persisted in all strata of knee alignment. Even among knees with valgus alignment, the prevalence of lateral PF cartilage damage equalled or surpassed that of medial PF damage only when the threshold was specific to severely involved knees. CONCLUSIONS: Medial PF cartilage damage is at least as prevalent within these older adult populations as lateral PF cartilage damage.

Relationship of Patellofemoral Osteoarthritis to Changes in Performance-based Physical Function Over 7 Years: The Multicenter Osteoarthritis Study.

OBJECTIVE: To determine the relationship of patellofemoral osteoarthritis (PFOA) to changes in performance-based function over 7 years. METHODS: There were 2666 participants (62.2 ± 8.0 yrs, BMI 30.6 ± 5.9 kg/m2, 60% female) from the Multicenter Osteoarthritis Study with knee radiographs at baseline who completed repeated chair stands and a 20-meter walk test (20MWT) at baseline, 2.5, 5, and 7 years. Generalized linear models assessed the relation of radiographic PFOA and radiographic PFOA with frequent knee pain to longitudinal changes in performance-based function. Analyses were adjusted for age, sex, BMI, tibiofemoral OA, and injury/surgery. RESULTS: Linear models demonstrated a significant group-by-time interaction for the repeated chair stands (P = 0.04) and the 20MWT (P < 0.0001). Those with radiographic PFOA took 1.01 seconds longer on the repeated chair stands (P = 0.02) and 1.69 seconds longer on the 20MWT (P < 0.0001) at 7 years compared with baseline. When examining the relation of radiographic PFOA with frequent knee pain to performance-based function, there was a significant group-by-time interaction for repeated chair stands (P = 0.05) and the 20MWT (P < 0.0001). Those with radiographic PFOA with frequent knee pain increased their time on the repeated chair stands by 1.12 seconds (P = 0.04) and on the 20MWT by 1.91 seconds (P < 0.0001) over 7 years. CONCLUSION: Individuals with radiographic PFOA and those with radiographic PFOA with frequent knee pain have worsening of performance-based function over time. This knowledge may present opportunities to plan for early treatment strategies for PFOA to limit functional decline over time.

Magnetic Resonance Imaging-Defined Osteoarthritis Features and Anterior Knee Pain in Individuals With, or at Risk for, Knee Osteoarthritis: A Multicenter Study on Osteoarthritis.

OBJECTIVE: The lack of strong association between knee osteoarthritis (OA) structural features and pain continues to perplex researchers and clinicians. Evaluating the patellofemoral joint in addition to the tibiofemoral joint alone has contributed to explaining this structure-pain discordance, hence justifying a more comprehensive evaluation of whole-knee OA and pain. The present study, therefore, was undertaken to evaluate the association between patellofemoral and tibiofemoral OA features with localized anterior knee pain (AKP) using 2 study designs. METHODS: Using cross-sectional data from the Multicenter Osteoarthritis Study, our first approach was a within-person, knee-matched design in which we identified participants with unilateral AKP. We then assessed magnetic resonance imaging (MRI)-derived OA features (cartilage damage, bone marrow lesions [BMLs], osteophytes, and inflammation) in both knees and evaluated the association of patellofemoral and tibiofemoral OA features to unilateral AKP. In our second approach, MRIs from 1 knee per person were scored, and we evaluated the association of OA features to AKP in participants with AKP and participants with no frequent knee pain. RESULTS: Using the first approach (n = 71, 66% women, mean ± SD age 69 ± 8 years), lateral patellofemoral osteophytes (odds ratio [OR] 5.0 [95% confidence interval (95% CI) 1.7-14.6]), whole-knee joint effusion-synovitis (OR 4.7 [95% CI 1.3-16.2]), and infrapatellar synovitis (OR 2.8 [95% CI 1.0-7.8]) were associated with AKP. Using the second approach (n = 882, 59% women, mean ± SD age 69 ± 7 years), lateral and medial patellofemoral cartilage damage (prevalence ratio [PR] 2.3 [95% CI 1.3-4.0] and PR 1.9 [95% CI 1.1-3.3], respectively) and lateral patellofemoral BMLs (PR 2.6 [95% CI 1.5-4.7]) were associated with AKP. CONCLUSION: Patellofemoral but not tibiofemoral joint OA features and inflammation were associated with AKP.

The Branching and Innervation Pattern of the Radial Nerve in the Forearm: Clarifying the Literature and Understanding Variations and Their Clinical Implications.

BACKGROUND: This study attempted to clarify the innervation pattern of the muscles of the distal arm and posterior forearm through cadaveric dissection. METHODS: Thirty-five cadavers were dissected to expose the radial nerve in the forearm. Each muscular branch of the nerve was identified and their length and distance along the nerve were recorded. These values were used to determine the typical branching and motor entry orders. RESULTS: The typical branching order was brachialis, brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, supinator, extensor digitorum, extensor carpi ulnaris, abductor pollicis longus, extensor digiti minimi, extensor pollicis brevis, extensor pollicis longus and extensor indicis. Notably, the radial nerve often innervated brachialis (60%), and its superficial branch often innervated extensor carpi radialis brevis (25.7%). CONCLUSIONS: The radial nerve exhibits significant variability in the posterior forearm. However, there is enough consistency to identify an archetypal pattern and order of innervation. These findings may also need to be considered when planning surgical approaches to the distal arm, elbow and proximal forearm to prevent an undue loss of motor function. The review of the literature yielded multiple studies employing inconsistent metrics and terminology to define order or innervation.

The Spectrum of Learning and Teaching: The Impact of a Fourth-Year Anatomy Course on Medical Student Knowledge and Confidence.

There is growing demand from accrediting agencies for improved basic science integration into fourth-year medical curricula and inculcation of medical students with teaching skills. The objective of this study was to determine the effectiveness of a fourth-year medical school elective course focused on teaching gross anatomy on anatomical knowledge and teaching confidence. Fourth-year medical student "teacher" participants' gross anatomy knowledge was assessed before and after the course. Students rated their overall perceived anatomy knowledge and teaching skills on a scale from 0 (worst) to 10 (best), and responded to specific knowledge and teaching confidence items using a similar scale. First-year students were surveyed to evaluate the effectiveness of the fourth-year student teaching on their learning. Thirty-two students completed the course. The mean anatomy knowledge pretest score and posttest scores were 43.2 (±22.1) and 74.1 (±18.4), respectively (P < 0.001). The mean perceived anatomy knowledge ratings before and after the course were 6.19 (±1.84) and 7.84 (±1.30), respectively (P < 0.0001) and mean perceived teaching skills ratings before and after the course were 7.94 (±1.24) and 8.53 (±0.95), respectively (P = 0.002). Student feedback highlighted five themes which impacted fourth-year teaching assistant effectiveness, including social/cognitive congruence and improved access to learning opportunities. Together these results suggest that integrating fourth-year medical students in anatomy teaching increases their anatomical knowledge and improves measures of perceived confidence in both teaching and anatomy knowledge. The thematic analysis revealed that this initiative has positive benefits for first-year students.

Reducing knee pain and loading with a gait retraining program for individuals with knee osteoarthritis: Protocol for a randomized feasibility trial.

Objective: This study aims to 1) determine the feasibility of conducting a full-scale randomized controlled trial (RCT) evaluating the efficacy of a gait retraining program on decreasing knee pain and impact loading in people with knee osteoarthritis, and 2) provide an estimate of treatment effects for a gait retraining program compared to a traditional walking program. Methods: Forty individuals with knee osteoarthritis will be enrolled in this randomized, double-blind, feasibility trial with two parallel groups. Participants will be randomly allocated to a gait retraining program aimed to decrease peak axial acceleration of the lower leg (i.e., tibia) by 20% or a traditional walking program. Both programs involve 8 sessions of walking on a treadmill. Feasibility will be assessed with recruitment, enrollment, and retention rates, and number of adverse events and unanticipated problems. Treatment effects will be estimated with measures of knee pain and impact loading collected at baseline, follow-up (<1 week post-intervention), and retention (≥1 month post-intervention) visits. Knee pain will be evaluated with the Western Ontario and McMaster Universities Osteoarthritis Index and impact loading will be measured during walking with three-dimensional motion analysis. Conclusion: Findings of this study will inform the feasibility of a full-scale RCT investigating the efficacy of a gait retraining program for people with knee osteoarthritis. Trial registration: (NCT04148807).

Patient-Reported Outcomes One to Five Years After Anterior Cruciate Ligament Reconstruction: The Effect of Combined Injury and Associations With Osteoarthritis Features Defined on Magnetic Resonance Imaging.

OBJECTIVE: Persistent symptoms and poor quality of life (QoL) are common following anterior cruciate ligament reconstruction (ACLR). We aimed to determine the influence of a combined ACL injury (i.e., concomitant meniscectomy and/or arthroscopic chondral defect at the time of ACLR and/or secondary injury/surgery to ACLR knee) and cartilage defects defined on magnetic resonance imaging (MRI), bone marrow lesions (BMLs), and meniscal lesions on patient-reported outcomes 1 to 5 years after ACLR. METHODS: A total of 80 participants (50 men; mean ± SD age 32 ± 14 years) completed the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the International Knee Documentation Committee (IKDC) questionnaires as well as a 3T MRI assessment at 1 and 5 years after ACLR. Median patient-reported outcome scores were compared between isolated and combined ACL injuries and with published normative values. Using multivariate regression, we evaluated the association between compartment-specific MRI cartilage, BMLs, and meniscal lesions and patient-reported outcomes at 1 and 5 years. RESULTS: Individuals with a combined injury had significantly worse scores in the KOOS subscale of function in sport and recreation (KOOS sport/rec) and in the IKDC questionnaire at 1 year, and worse scores in the KOOS subscales of pain (KOOS pain), symptoms (KOOS symptoms), and QoL (KOOS QoL) and in the IKDC questionnaire at 5 years compared to those with an isolated injury. Although no feature on MRI was associated with patient-reported outcomes cross-sectionally at 1 year, patellofemoral cartilage defects at 1 year were significantly associated with worse 5-year KOOS symptoms (ß = -9.79, 95% confidence interval [95% CI] -16.67, -2.91), KOOS sport/rec (ß = -7.94, 95% CI -15.27, -0.61), KOOS QoL (ß = -8.29, 95% CI -15.28, -1.29), and IKDC (ß = -4.79, 95% CI -9.34, -0.24) scores. Patellofemoral cartilage defects at 5 years were also significantly associated with worse 5-year KOOS symptoms (ß = -6.86, 95% CI -13.49, -0.24) and KOOS QoL (ß = -11.71, 95% CI -19.08, -4.33) scores. CONCLUSION: Combined injury and patellofemoral cartilage defects shown on MRI are associated with poorer long-term outcomes. Clinicians should be vigilant and aware of individuals with these injuries, as such individuals may benefit from targeted interventions to improve QoL and optimize symptoms.