Muscle Strength Deficits Research Articles

A Portable Passive Rehabilitation Robot for Upper-Extremity Functional Resistance Training.

Loss of arm function is common in individuals with neurological damage, such as stroke or cerebral palsy. Robotic devices that address muscle strength deficits in a task-specific manner can assist in the recovery of arm function; however, current devices are typically large, bulky, and expensive to be routinely used in the clinic or at home. This study sought to address this issue by developing a portable planar passive rehabilitation robot, PaRRo. We designed PaRRo with a mechanical layout that incorporated kinematic redundancies to generate forces that directly oppose the user's movement. Cost-efficient eddy current brakes were used to provide scalable resistances. The lengths of the robot's linkages were optimized to have a reasonably large workspace for human planar reaching. We then performed theoretical analysis of the robot's resistive force generating capacity and steerable workspace using MATLAB simulations. We also validated the device by having a subject move the end-effector along different paths at a set velocity using a metronome while simultaneously collecting surface electromyography (EMG) and end-effector forces felt by the user. Results from simulation experiments indicated that the robot was capable of producing sufficient end-effector forces for functional resistance training. We also found the endpoint forces from the user were similar to the theoretical forces expected at any direction of motion. EMG results indicated that the device was capable of providing adjustable resistances based on subjects' ability levels, as the muscle activation levels scaled with increasing magnet exposures. These results indicate that PaRRo is a feasible approach to provide functional resistance training to the muscles along the upper extremity. The proposed robotic device could provide a technological breakthrough that will make rehabilitation robots accessible for small outpatient rehabilitation centers and in-home therapy.

Relationship Between Rotator Cuff Strength & Functional Scores After Bankart Repair

PURPOSE: The anterior instability is representing approximately 95% of all shoulder instabilities that mainly caused by an abduction, extension, and external rotation of the shoulder movement. However capsular laxity and unstable glenohumeral joint which make the most frequently dislocated joint in shoulder have closely related with rotator cuff weakness. This study examines the association between strength and functional indices in patients with Bankart repair. The purpose of the study is the relationship between internal rotator and external rotator muscle strength, shoulder functional indices (ROWE and ASES scores) post one year of the Bankart repair. METHODS: This was a cross sectional study comprising of 40 patients, all males (24.5±13.5 yrs, ht 169.3±8.5 kg, and wt 67.8±11.4 kg) with Bankart lesion who may be treated arthroscopically. Isokinetic internal rotator(IR) and external rotator(ER) strength were evaluated with a CSMI dynamometer, with the subject seated and the shoulder abducted 45 in the scapular plane. Tests were performed at 60 /sec concentric mode for both sides. Shoulder strength was analyzed by comparison between involved side strength deficit and uninvolved side (side-to-side differences). Preoperatively and postoperatively, all the ROWE and ASES(American Shoulder and Elbow Surgeons) score was recorded that included subscores for ROM, muscle strength, pain, motion, and function.by the same exercise physiologist. RESULTS: The patients were divided into 4 groups for comparison in muscle strength deficit- Q1 (less than 20% difference in muscle strength deficit), Q2 (21-35% deficit), Q3 (36-50% deficit), and Q4 (more than 50% difference in muscle strength deficit). In our study, ROWE and ASES score (r = - .305; r = - .382) were significantly correlative difference in Q1 (less than 20% deficit) group with IR and ER muscle strength. CONCLUSIONS: This study suggests that muscle strength of the shoulder after Bankart repair will affect the functional ability more than any other factor. The muscle strength deficits in shoulder joint have significant negative consequences for the long term functional outcome after Bankart lesion. Therefore, it is deemed necessary to measure the muscle strength of the rotator cuff and continue rehabilitation exercise needed for recovery of muscle strength.

Fresh whole blood resuscitation does not exacerbate skeletal muscle edema and long-term functional deficit after ischemic injury and hemorrhagic shock.

Hemorrhagic shock caused by extremity vascular injuries is common in combat injuries. Fluid resuscitation is the standard treatment for severe hemorrhage (HEM). Tourniquets (TKs) used for HEM control cause ischemia-reperfusion (I/R) injury that induces edema formation in the injured muscle. Resuscitation fluids affect edema formation; however, its effect on long-term functional response remains unknown. The objectives of this study are to (1) compare acute muscle damage; (2) determine long-term functional recovery of ischemic muscle; and (3) compare local and systemic inflammatory response including the expression of junctional proteins following early resuscitation with Hextend and fresh whole blood using a rodent model of combined HEM and TK-induced limb I/R. Anesthetized Sprague-Dawley rats underwent 42.5% arterial HEM, followed by 3 hours of TK application. Animals were either not resuscitated or resuscitated with Hextend or fresh whole blood. Two time points were evaluated, 2 and 28 days. Plasma cytokine concentrations were determined at baseline and end resuscitation. At 2 days, edema formation, expression of junctional proteins, and tissue level cytokines concentrations were evaluated. At 28 days, in vivo muscle contractile properties were determined. At both time points, routine histology was performed and graded using a semiquantitative grading system. All animals developed hemorrhagic hypovolemia; the mortality rate was 100% in nonresuscitated rats. Hextend resuscitation exacerbated muscle edema (~11%) and muscle strength deficit (~20%). Fresh whole blood resuscitation presented edema and muscle strength akin to TK only. Fresh whole blood resuscitation upregulated expression of junctional proteins including proangiogenic factors and dampened the inflammatory response. Fresh whole blood resuscitation does not exacerbate either TK-induced edema or muscle strength deficit. Fresh whole blood resuscitation may reduce both acute and long-term morbidity associated with extremity trauma. To our knowledge, this is the first study to demonstrate the nature of the resuscitation fluid administered following HEM impacts short- and long-term indices of I/R in skeletal muscle.

The Utility of Objective Strength and Functional Performance to Predict Subjective Outcomes After Anterior Cruciate Ligament Reconstruction.

Background:Many clinicians release patients to return to activity after anterior cruciate ligament reconstruction (ACLR) based on time from surgery despite deficits in muscle strength and function. It is unclear whether symmetry or unilateral performance is the best predictor of subjective outcomes after ACLR.Purpose:To determine physical performance predictors of patient-reported outcomes after reconstruction.Study Design:Cross-sectional study; Level of evidence, 3.Methods:A total of 88 participants (49 males, 39 females; mean ± SD height, 174.0 ± 9.6 cm; weight, 76.1 ± 18.5 kg; age, 19.4 ± 3.7 years) who underwent primary, unilateral ACLR volunteered for this study. Participants had undergone reconstruction a mean of 6.9 ± 1.8 months (range, 5.0-14.1 months) before the study. All participants underwent strength testing as well as hop testing and then completed the International Knee Documentation Committee (IKDC) and Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaires. Stepwise linear regression models were used for symmetry and unilateral performance to identify the proportion of variance explained in the IKDC score, KOOS total score, KOOS-sport subscale, and time from surgery, as well as receiver operating characteristic (ROC) curve analyses on those variables that explained the most variance in patient-reported outcomes to determine cutoff thresholds.Results:No significant correlations were found between time from surgery and objective performance. The only significant predictors of IKDC score were single-hop limb symmetry index (LSI) and age (R 2 = 0.177) and unilateral triple-hop performance and age (R 2 = 0.228). The cutoff for single-hop symmetry was 0.92 (area under the curve [AUC], 0.703; P = .012), and the cutoff for normalized triple-hop distance was 3.93 (AUC, 0.726; P = .005). When stratified by age, the cutoff for single-hop symmetry was 0.81 (AUC, 0.721; P = .051) for younger patients (age <19.1 years) and was not significant for older patients (age ≥19.1 years). The cutoff for normalized triple-hop distance was 3.85 (AUC, 0.832; P = .005) in older patients and was not significant for younger patients. The only significant predictors of KOOS-sport subscale were single-hop LSI (R 2 = 0.140) and normalized knee extensor power at 180 deg/s (R 2 = 0.096). When subjective outcomes were predicted based on KOOS-sport subscale, the cutoff for single-hop symmetry was 0.85 (AUC, 0.692; P = .018).Conclusion:Hopping performance is the most predictive functional variable of subjective outcomes after reconstruction. Single-hop symmetry was most important for younger patients and unilateral triple-hop distance was most important for older patients. Clinicians should consider hopping performance when making return-to-activity decisions after ACLR.

Fatty Degeneration of the Rotator Cuff Reflects Shoulder Strength Deficits in Patients With Rotator Cuff Tears.

Fatty degeneration is an important clinical factor in patients with rotator cuff tears. Goutallier grade, occupation ratio, and tangent sign help identify fatty degeneration; however, little is known about how closely these measurement techniques correlate with actual muscle strength deficits. The authors evaluated each method's ability to determine the correlation between fatty degeneration and muscle strength deficits. The authors included 203 patients who underwent full-thickness rotator cuff repair (mean age, 61.29±7.92 years). All patients were evaluated with preoperative magnetic resonance imaging to identify fatty degeneration and with an isokinetic test to determine actual shoulder strength. Fatty degeneration was evaluated using Goutallier grade, occupation ratio, and tangent sign. The actual shoulder strength deficit was evaluated by abduction, whereas external and internal rotation were tested using the isokinetic test. More severe fatty degeneration was correlated with lower degrees of abduction, external rotation, and internal rotation. The occupation ratio was more closely correlated with actual muscle strength deficits. However, in patients with massive tears, the correlation between fatty degeneration and muscle strength was less pronounced. Tangent sign (+) findings had a significantly lower strength of external rotation and abduction. The fatty degeneration of the rotator cuff muscle measured by each method was correlated with actual shoulder strength deficits in patients with rotator cuff tears. However, the correlations were less clear in patients with massive rotator cuff tears. Therefore, in cases of massive rotator cuff tears, fatty degeneration was correlated with muscle strength deficits but was not directly proportional to their extent. [Orthopedics. 2018; 41(1):e15-e21.].

Calf Muscle Performance Deficits Remain 7 Years After an Achilles Tendon Rupture

Background: Optimizing calf muscle performance seems to play an important role in minimizing impairments and symptoms after an Achilles tendon rupture (ATR). The literature lacks long-term follow-up studies after ATR that describe calf muscle performance over time. Purpose: The primary aim was to evaluate calf muscle performance and patient-reported outcomes at a mean of 7 years after ATR in patients included in a prospective, randomized controlled trial. A secondary aim was to evaluate whether improvement in calf muscle performance continued after the 2-year follow-up. Study Design: Cohort study; Level of evidence, 2. Methods: Sixty-six subjects (13 women, 53 men) with a mean age of 50 years (SD, 8.5 years) were evaluated at a mean of 7 years (SD, 1 year) years after their ATR. Thirty-four subjects had surgical treatment and 32 had nonsurgical treatment. Patient-reported outcomes were evaluated with Achilles tendon Total Rupture Score (ATRS) and Physical Activity Scale (PAS). Calf muscle performance was evaluated with single-leg standing heel-rise test, concentric strength power heel-rise test, and single-legged hop for distance. Limb Symmetry Index (LSI = injured side/healthy side × 100) was calculated for side-to-side differences. Results: Seven years after ATR, the injured side showed decreased values in all calf muscle performance tests (P < .001-.012). Significant improvement in calf muscle performance did not continue after the 2-year follow-up. Heel-rise height increased significantly (P = .002) between the 1-year (10.8 cm) and the 7-year (11.5 cm) follow-up assessments. The median ATRS was 96 (of a possible score of 100) and the median PAS was 4 (of a possible score of 6), indicating minor patient-reported symptoms and fairly high physical activity. No significant differences were found in calf muscle performance or patient-reported outcomes between the treatment groups except for the LSI for heel-rise repetitions. Conclusion: Continued deficits in calf muscle endurance and strength remained 7 years after ATR. No continued improvement in calf muscle performance occurred after the 2-year follow-up except for heel-rise height.

Arthroscopic subscapularis repair using single-row mattress suture technique: clinical results and structural integrity

Rupture of the subscapularis (SSC) tendon, isolated or combined, is rare, and the treatment modalities are controversial. The purpose of this study was to evaluate, by magnetic resonance imaging (MRI), the clinical outcomes and structural integrity of the SSC tendon after all-arthroscopic repair with single-row mattress suture for isolated or combined SSC tendon tears. This study included 68 patients who underwent all-arthroscopic repair using single-row mattress suture for isolated or combined SSC tendon tears between April 2011 and January 2013. The patients were evaluated by the visual analog scale for pain, American Shoulder and Elbow Surgeons score, Constant shoulder score, and SSC muscle strength measurement. MRI was used for assessment of the postoperative integrity of the SSC tendon. With a mean follow-up of 29.5 ± 4.0 months, the preoperative Constant shoulder and American Shoulder and Elbow Surgeons scores were 50.3 ± 21.0 and 46.6 ± 18.3, respectively, which improved at the last follow-up to 75.7 ± 16.6 and 81.3 ± 18.1, respectively, with statistical significance (P < .001). Belly-press and bear-hug test results showed some improvement in the last follow-up (>2 years) compared with the presurgical state (P = .125 and .650). A statistically significant SSC muscle strength deficit persisted in the postoperative state (P = .015). MRI evaluation showed a retear rate of 8.8%. Arthroscopic repair of isolated or combined SSC tears with the single-row mattress suture technique results in significant clinical improvements and enduring tendon integrity, although SSC strength remains reduced from that on the normal side.

Functional results and isokinetic muscle strength in patients with Fraser type I floating knee treated with internal fixation

IntroductionAccording to Fraser’s description, ipsilateral femoral and tibial diaphyseal fractures are characterised as type I floating knee and have a better prognosis than fractures with joint involvement (type II). There are few reports of functional and muscle strength in these patients. The objective of this study was to evaluate the functional and isokinetic muscle strength of patients with type I floating knee undergoing femoral and tibial internal fixation. MethodsPatients with type I floating knee undergoing concomitant femoral and tibial internal fixation were invited for clinical evaluation. The parameters evaluated included the following: Karlstrom and Olerud score; Lysholm score; isokinetic thigh and hip muscle evaluation; knee range of motion; pain level; investigation of associated knee injuries by clinical evaluation and MRI; and types of complications. ResultsTwenty-one patients were included in the study; 11 of these were clinically evaluated, with a mean follow-up of 23.9 months. Six patients had an acceptable result according to the Karlstrom criteria, whereas eight patients had a poor result based on the Lysholm scale. The peak torque deficit was 61% for knee extensors, 37% for flexors and -9% for hip abductors. The mean pain level was 5.9. Three patients had a partial anterior cruciate ligament (ACL) injury; one patient had a posterior cruciate ligament (PCL) injury; and three patients had a meniscal injury. There were four cases of tibial or femoral nonunion at one year and two cases of chronic osteomyelitis. ConclusionPatients with type I floating knee had unsatisfactory functional results, significant knee extensor and flexor muscle strength deficits and a significant rate of complications at the two-year follow-up.

Calf Muscle Atrophy and Achilles Tendon Elongation After Acute Achilles Tendon Rupture

Calf muscle atrophy and Achilles tendon elongation seems to be the principal structural explanations for calf muscle strength deficit at short and long term follow up and also explain surgery related greater plantar flexion strength compared conservative treatment after acute Achilles tendon rupture. Despite good clinical results of surgery and conservative treatment for acute Achilles tendon rupture (ATR), surgery may result in 10-18% better calf muscle strength. However, 12-18% strength deficit compared to the unaffected leg usually remains even in long-term follow up. We aimed to assess whether Achilles tendon elongation and calf muscle volume changes could explain the difference in calf muscle strength between conservative treatment and surgery and side-to side strength deficit of calf muscle for patients with operatively treated ATR in long term follow-up. Group 1; 60 patients with acute ATRs were randomized to surgery or conservative treatment. Conservative treatment and post operative treatments were identical; cast immobilization for one week, followed by functional orthosis for 6 weeks, which allowed full weight bearing after week 1 and active plantar flexion after week 5 post injury. At 18 months, MRI was used to evaluate the volume of calf muscles and the length of the affected Achilles tendon. Group 2; 60 patients with acute ATRs were randomized to simple end-to-end repair or augmented repair, both with postoperative bracing allowing free active plantar flexion for 3 weeks. After follow-up of =13 years, 55 patients (28 non-augmented, 27 augmented) were re-examined and MRI was used to evaluate the volume of calf muscles, and the length of the Achilles tendons for both legs. Group 1; At 18 months, the mean differences between healthy and affected soleus muscle volumes were 83.2 cm3 (17.7%) after surgery and 115.5 cm3 (24.8%) after conservative treatments (difference between means: 33.1 cm3, 95% CI: 1.3 to 65.0, p = 0.042). Achilles tendon length from calcaneal insertion to soleus muscle MTJ for affected leg was 18.7mm longer for conservative treatment compared operative treatment (95% CI: 8.5 to 28.8, p<0.001). All patients in group 1 suffered up to 21% calf muscle atrophy for affected leg, which was compensated by 11% hypertrophy in flexor hallucis longus (FHL) (p=0.001 in all). Group 2; At 14 years patients in group 2 suffered up to 12% calf muscle atrophy for affected leg which was compensated by 5.4% hypertrophy in flexor halluces longus (FHL) (p=0.001 in all). Achilles tendon length from calcaneal insertion to medial gastrocnemius muscle MTJ for affected leg was 12.1mm longer compared healthy tendon (95% CI, 8.6 to 15.6, p<0.001). At 18 months ATR conservative treatment with a functional rehabilitation protocol resulted in greater soleus muscle atrophy and 19 mm longer calcaneus to soleus MTJ length to surgical treatment. At 14 years ATR operative treatment resulted up to 12% calf muscle atrophy and 12mm longer Achilles tendon of the affected leg. Calf muscle atrophy in the affected leg was compensated with hypertrophy of the FHL both in short and long term follow-up. Achilles tendon elongation may be the principal structural explanation of calf muscle atrophy and muscle strength deficit at short and long term follow-up after ATR.

Evaluation of the Function and Quality of Life after Total Hip Arthroplasty by Different Approaches

To assess the function and quality of life in patients undergoing total hip arthroplasty distinguishing two surgical approaches (posterior / anterolateral) used by the Orthopedics department of Centro Hospitalar de Leiria. Retrospective study of 94 patients subject to unilateral hip replacement surgery, using the 'Hip Osteoarthritis Outcome Score' (HOOS LK 2.0) questionnaire, the Trendelenburg test and evaluation of muscle strength of the hip abductor muscles with dynamometer. Patients were evaluated at six months, 12 months, 18 months and 24 months after surgery. The study revealed that 97.9% patients completed the rehabilitation program. The postoperative evolution (six to 24 months) does not appear to have any differences in results when comparing both approaches. At six months the patient operated by the anterolateral approach showed worse results when compared with the posterior approach, in particular in Hip Osteoarthritis Outcome Score pain, in Hip Osteoarthritis Outcome Score symptoms and Hip Osteoarthritis Outcome Score activities of daily living. After 24 months, no differences between the two surgical approaches were found. Of the 94 patients evaluated, the Trendelenburg test was positive in 31% of patients of which 81.9% corresponds to patients operated by the anterolateral approach. Muscle strength of the abductors of the operated hip was clearly lower in the anterolateral approach at six months, 12 months, and 24 months. This study showed that, in the first six months after total hip arthroplasty, the patients operated by the posterior approach were, according to the HOOS questionnaire, less symptomatic, and presented with better quality of life and less impact on activities of daily living and in sport and leisure when compared with the patients operated by the anterolateral approach. However, these differences were matched over the 24 months. Moreover, the results of muscle strength of the abductor muscles of the hip were clearly superior in patients operated by the posterior approach at six months, at 12 months and at 24 months compared to the patients operated by the anterolateral approach. After 24 months post total hip arthroplasty there are no differences between the two approaches with regard to function or quality of life. However, the patients operated by the anterolateral approach had greater muscle strength deficits and higher percentage of positive Trendelenburg test.

Reduced muscle strength in ether lipid-deficient mice is accompanied by altered development and function of the neuromuscular junction.

Inherited deficiency in ether lipids, a subgroup of phospholipids whose biosynthesis needs peroxisomes, causes the fatal human disorder rhizomelic chondrodysplasia punctata. The exact roles of ether lipids in the mammalian organism and, therefore, the molecular mechanisms underlying the disease are still largely enigmatic. Here, we used glyceronephosphate O‐acyltransferase knockout (Gnpat KO) mice to study the consequences of complete inactivation of ether lipid biosynthesis and documented substantial deficits in motor performance and muscle strength of these mice. We hypothesized that, probably in addition to previously described cerebellar abnormalities and myelination defects in the peripheral nervous system, an impairment of neuromuscular transmission contributes to the compromised motor abilities. Structurally, a morphologic examination of the neuromuscular junction (NMJ) in diaphragm muscle at different developmental stages revealed aberrant axonal branching and a strongly increased area of nerve innervation in Gnpat KO mice. Post‐synaptically, acetylcholine receptor (AChR) clusters colocalized with nerve terminals within a widened endplate zone. In addition, we detected atypical AChR clustering, as indicated by decreased size and number of clusters following stimulation with agrin, in vitro. The turnover of AChRs was unaffected in ether lipid‐deficient mice. Electrophysiological evaluation of the adult diaphragm indicated that although evoked potentials were unaltered in Gnpat KO mice, ether lipid deficiency leads to fewer spontaneous synaptic vesicle fusion events but, conversely, an increased post‐synaptic response to spontaneous vesicle exocytosis. We conclude from our findings that ether lipids are essential for proper development and function of the NMJ and may, therefore, contribute to motor performance. Read the Editorial Highlight for this article on page 463.

Evaluation of Skeletal Muscle Function in Lung Transplant Candidates.

Lung transplantation (LTx) is offered to older and more complex patients who may be at higher risk of skeletal muscle dysfunction, but the clinical implications of this remain uncertain. The study aims were to characterize deficits in skeletal muscle mass, strength and physical performance, and examine the associations of these deficits with clinical outcomes. Fifty LTx candidates (58% men; age, 59 ± 9 years) were prospectively evaluated for skeletal muscle deficits: muscle mass using bioelectrical impedance, quadriceps, respiratory muscle and handgrip strength, and physical performance with the Short Physical Performance Battery. Comparisons between number of muscle deficits (low muscle mass, quadriceps strength and physical performance) and 6-minute walk distance (6MWD), London Chest Activity of Daily Living Questionnaire, and quality of life were assessed using one-way analysis of variance. Associations with pretransplant and posttransplant delisting/mortality, hospital duration, and 3-month posttransplant 6MWD were evaluated using Fisher exact test and Spearman correlation. Deficits in quadriceps strength (n = 27) and physical performance (n = 24) were more common than muscle mass (n = 8). LTx candidates with 2 or 3 muscle deficits (42%) compared with those without any deficits (26%) had worse 6MWD = -109 m (95% confidence interval [CI], -175 to -43), London Chest Activity of Daily Living Questionnaire = 18 (95% CI, 7-30), and St. George's Activity Domain = 12 (95% CI, 2-21). Number of muscle deficits was associated with posttransplant hospital stay (r = 0.34, P = 0.04), but not with delisting/mortality or posttransplant 6MWD. Deficits in quadriceps muscle strength and physical performance are common in LTx candidates and further research is needed to assess whether modifying muscle function pretransplant can lead to improved clinical outcomes.

Trunk Muscle Function Deficit in Youth Baseball Pitchers With Excessive Contralateral Trunk Tilt During Pitching.

Pitching technique is one of many factors that affect injury risk. Exhibiting excessive contralateral trunk tilt (CLT) during pitching has been linked to higher ball speed but also to increased joint loading. Deficit in trunk muscle strength has been suggested as an underlying cause of this movement pattern. The purpose of the study was to compare trunk muscle strength between youth baseball pitchers with varying degree of CLT during pitching. Cross-sectional study. Baseball practice fields. Twenty-eight youth baseball pitchers. Pitching technique was captured using a video camera. Based on the 2-dimensional trunk contralateral flexion angle, pitchers were categorized into low (<15 degrees), moderate (15-30 degrees), or high (>30 degrees) CLT groups. Maximum isometric strength tests for trunk flexion, extension, and bilateral rotation, measured using a dynamometer. The pitchers with high CLT (n = 10) had longer pitching experience (P = 0.014), produced higher ball speed (P = 0.003) compared with the pitchers with moderate (n = 10) and low (n = 8) CLT, but demonstrated greater asymmetry in trunk rotation strength (relative weakness in rotation strength toward dominant side) compared with the pitchers with low CLT (P = 0.015). Excessive CLT may be a strategy that young pitchers learn to achieve higher ball velocity but also may be associated with imbalance between the oblique muscles on dominant and nondominant side, which may be acquired from repetitive pitching. Strengthening and emphasizing the use of dominant side oblique muscles may keep pitchers from leaning excessively during pitching and thus decrease joint loading.

CORR Insights®: Younger Patients and Men Achieve Higher Outcome Scores Than Older Patients and Women After Anterior Cruciate Ligament Reconstruction.

CORR Insights®: Younger Patients and Men Achieve Higher Outcome Scores Than Older Patients and Women After Anterior Cruciate Ligament Reconstruction.

Thigh Muscle Specific‐Strength and the Risk of Incident Knee Osteoarthritis: The Influence of Sex and Greater Body Mass Index

To determine whether lower thigh muscle specific-strength increases the risk of incident radiographic knee osteoarthritis (RKOA), and whether there exists a sex-specific relationship between thigh muscle specific-strength and body mass index (BMI). A total of 161 Osteoarthritis Initiative participants (62% female) with incident RKOA (Kellgren/Lawrence grade 0/1 at baseline, developing an osteophyte and joint space narrowing grade ≥1 by year 4) were matched to 186 controls (58% female) without incident RKOA. Thigh muscle anatomical cross-sectional areas (ACSAs) were determined at baseline using axial magnetic resonance imaging scans. Isometric extensor and flexor muscle strength was measured at baseline, and specific strength (strength ÷ ACSA) was calculated. Logistic regression assessed the risk of incident RKOA associated with muscle specific-strength (with and without adjustment for BMI). Lower knee extensor- and flexor-specific strength significantly increased the risk of incident RKOA in women but not in men (odds ratio 1.47 [95% confidence interval (95% CI) 1.10-1.96] and 1.41 [95% CI 1.06-1.89], respectively). The significant relationship in women was lost after adjustment for BMI. Lower specific strength was associated with higher BMI in women (r = -0.29, P < 0.001), but not in men, whereas absolute strength was associated with BMI in men (r = 0.28, P = 0.001), but not in women. Lower thigh muscle specific-strength predicts incident RKOA in women, with this relationship being confounded by BMI. The sex-specific relationship between muscle specific-strength and BMI provides a possible explanation why women with muscle-strength deficits typically have a poorer prognosis than men with similar strength deficits.

Hip rate of force development and strength are impaired in females with patellofemoral pain without signs of altered gluteus medius and maximus morphology

ObjectivesTo compare rate of force development (RFD) and isometric muscle strength of the hip abductors and extensors; and the thickness and the amount of non-contractile tissue of the gluteus medius and maximus between females with and without patellofemoral pain (PFP). DesignCross-sectional study. MethodsFifty-four physically active females (27 with PFP and 27 healthy individuals) were studied. Hip muscle isometric strength and RFD was evaluated using isokinetic dynamometry. RFD was measured until 30%, 60%, and 90% of the maximal isometric torque (MIT). Hip muscle morphology was evaluated using ultrasonography. ResultsThe PFP group possessed slower RFD compared to the control group by 33% for hip abductors until 90%MIT (−0.23%/ms, 95%CI −0.44 to −0.02, ES=0.59); by 51% for hip extensors until 30%MIT (−0.42%/ms, 95%CI −0.66 to −0.18, ES=0.97); and by 55% for hip extensors until 60%MIT (−0.36%/ms, 95%CI −0.60 to −0.12, ES=0.81). The PFP group possessed reduced isometric torque compared to the control group by 10% for hip abduction (−16.0Nm/kg×100, 95% CI −30.2 to −1.9, ES=0.61) and by 15% for hip extension (−30.1Nm/kg×100, 95%CI −51.4 to −8.9, ES=0.76). No significant between group differences for the thickness and the amount of non-contractile tissue of the gluteus medius and maximus were identified. ConclusionsFemales with PFP have deficits in isometric strength and RFD in hip abduction and extension. RFD deficits are greater than strength deficits which may highlight their potential importance. Hip muscle strength and RFD deficits do not appear to be explained by muscle thickness or proportion of non-contractile tissue of the gluteal musculature as measured by ultrasound.

Quadriceps Strength in Patients With Isolated Cartilage Defects of the Knee: Results of Isokinetic Strength Measurements and Their Correlation With Clinical and Functional Results.

Background:Recent studies have found a significant deficit of maximum quadriceps strength after autologous chondrocyte implantation (ACI) of the knee. However, it is unclear whether muscular strength deficits in patients with cartilage damage exist prior to operative treatment.Purpose:To isokinetically test maximum quadriceps muscle strength and quantify the impact of possible strength deficits on functional and clinical test results.Study Design:Cross-sectional study; Level of evidence, 3.Methods:To identify clinically relevant muscular strength deficits, 24 patients (5 females, 19 males; mean age, 34.5 years; body mass index, 25.9 kg/m2) with isolated cartilage defects (mean onset, 5.05 years; SD, 7.8 years) in the knee joint underwent isokinetic strength measurements. Maximal quadriceps strength was recorded in 3 different testing modes: pure concentric contraction (flexors and extensors alternating work; con1), concentric-eccentric (only the extensors work concentrically and eccentrically; con2), and eccentric contraction in the alternating mode (ecc). Results were compared for functional performance (single-leg hop test), pain scales (visual analog scale [VAS], numeric rating scale [NRS]), self-reported questionnaires (International Knee Documentation Committee [IKDC], Knee Injury and Osteoarthritis Outcome Scale [KOOS]), and defect size (cm2).Results:Compared with the uninjured leg, significantly lower quadriceps strength was detected in the injured leg in all isokinetic working modes (con1 difference, 27.76 N·m [SD 17.47; P = .003]; con2 difference, 21.45 N·m [SD, 18.45; P =.025]; ecc difference, 29.48 N·m [SD, 21.51; P = .001]), with the largest deficits found for eccentric muscle performance. Moderate negative correlations were observed for the subjective pain scales NRS and VAS. The results of the IKDC and KOOS questionnaires showed low, nonsignificant correlations with findings in the isokinetic measurement. Moreover, defect sizes (mean, 3.13 cm2) were of no importance regarding the prediction of the strength deficit. The quadriceps strength deficit between the injured and the uninjured leg was best predicted by the results of the single-leg hop test.Conclusion:Patients with isolated cartilage defects of the knee joint have significant deficits in quadriceps muscle strength of the injured leg compared with the uninjured leg. The single-leg hop test may be used to predict quadriceps strength deficits. Future research should address whether preoperative strength training in patients with cartilage defects of the knee could be effective and should be taken into consideration in addition to surgical treatment.

Muscle Strength and Power Deficits in Children with Type SS Sickle Cell Disease

Muscle Strength and Power Deficits in Children with Type SS Sickle Cell Disease

HAMSTRING MORPHOLOGY AND STRENGTH REMAIN ALTERED 2 YEARS FOLLOWING A HAMSTRING GRAFT IN ACL RECONSTRUCTION

Background:The hamstring graft used in anterior cruciate ligament (ACL) reconstruction has been shown to lead to changes to the semitendinosus and gracilis musculature. This study further evaluated the effect of the surgery on hamstring muscle morphology and knee muscle strength at 2 years post-surgery.Hypotheses:(1) Loss of donor muscle size would significantly correlate with knee muscle strength deficits (2) Loss of donor muscle size would be greater for muscles that do not experience tendon regeneration, and (3) Morphological adaptations would also be evident in non-donor knee muscles.Study Design:Cross sectional evaluation.Methods:20 participants (14 male, 6 female, 29 ± 7 years, 82 ± 15 kg) that had undergone a hamstring graft in ACL reconstruction at least two years previously, underwent bilateral MRI and subsequent strength testing. Muscle and tendon volumes, peak CSA’s and lengths were determined for 12 muscles and 6 functional muscle groups of the surgical and contralateral limbs. Peak isokinetic concentric strength was measured in knee flexion/extension and internal/external tibial rotation.Results:Only 50% of the patients regenerated both the semitendinosus and gracilis tendons. The regenerated tendons were longer with larger volume and CSA compared to the contralateral side. Deficits in semitendinosus and gracilis muscle size were greater for tendons that did not regenerate. In addition, combined hamstrings (semitendinosus, semimembranosus, biceps femoris) and combined medial knee muscles (semitendinosus, semimembranosus, gracilis, vastus medialis, medial gastrocnemius, sartorius) on the surgical side were reduced in volume by 12% and 10% respectively. A 7% larger volume was observed in the surgical leg for the biceps femoris and corresponded with a lower internal/external tibial rotation strength ratio. The difference in volume, peak CSA and length of the semitendinosus and gracilis correlated significantly with the deficit in knee flexion strength with Pearson correlations of 0.51, 0.57 and 0.61 respectively.Conclusion:The muscle-tendon properties of the semitendinosus and gracilis are substantially altered following harvesting, and these alterations may contribute to knee flexor weakness in the surgical limb. These deficits are more pronounced in tendons that do not regenerate and are only partially offset by compensatory hypertrophy of other hamstring muscles.Clinical Relevance:Surgeons should consider muscle retraction of the hamstring following tendon harvest in their choice of graft option for ACL reconstruction.

Soleus Atrophy Is Common After the Nonsurgical Treatment of Acute Achilles Tendon Ruptures: A Randomized Clinical Trial Comparing Surgical and Nonsurgical Functional Treatments

Background: It remains controversial whether nonsurgical or surgical treatment provides better calf muscle strength recovery after an acute Achilles tendon rupture (ATR). Recent evidence has suggested that surgery might surpass nonsurgical treatment in restoring strength after an ATR. Purpose: To assess whether magnetic resonance imaging (MRI) findings could explain calf muscle strength deficits and the difference between nonsurgical and surgical treatments in restoring calf muscle strength. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: From 2009 to 2013, 60 patients with acute ATRs were randomized to surgery or nonsurgical treatment with an identical rehabilitation protocol. The primary outcome measure was the volume of calf muscles assessed using MRI at 3 and 18 months. The secondary outcome measures included fatty degeneration of the calf muscles and length of the affected Achilles tendon. Additionally, isokinetic plantarflexion strength was measured in both legs. Results: At 3 months, the study groups showed no differences in muscle volumes or fatty degeneration. However, at 18 months, the mean differences between affected and healthy soleus muscle volumes were 83.2 cm3 (17.7%) after surgery and 115.5 cm3 (24.8%) after nonsurgical treatment (difference between means, 33.1 cm3; 95% CI, 1.3-65.0; P = .042). The study groups were not substantially different in the volumes or fatty degeneration of other muscles. From 3 to 18 months, compensatory hypertrophy was detected in the flexor hallucis longus (FHL) and deep flexors in both groups. In the nonsurgical treatment group, the mean difference between affected and healthy FHL muscle volumes was −9.3 cm3 (12%) and in the surgical treatment group was −8.4 cm3 (10%) (P ≤ .001). At 18 months, Achilles tendons were, on average, 19 mm longer in patients treated nonsurgically compared with patients treated surgically (P < .001). At 18 months, surgically treated patients demonstrated 10% to 18% greater strength results (P = .037). Calf muscle isokinetic strength deficits for the entire range of ankle motion correlated with soleus atrophy (ρ = 0.449-0.611; P < .001). Conclusion: Treating ATRs nonsurgically with a functional rehabilitation protocol resulted in greater soleus muscle atrophy compared with surgical treatment. The mean Achilles tendon length was 19 mm longer after nonsurgical treatment than after the surgical treatment of ATRs. These structural changes partly explained the 10% to 18% greater calf muscle strength observed in patients treated with surgery compared with those treated nonsurgically. Registration: NCT02012803 (ClinicalTrials.gov identifier).