Effects of amino acid supplementation on muscle mass, muscle performance and functional capacity in subjects undergoing total knee arthroplasty: a systematic review of randomized clinical trials

The aim of the present study was to summarize the effectiveness of amino acid supplementation on muscle strength, muscle volume, and functional capacity in patients undergoing total knee arthroplasty. For this, in November 2022, a search was carried out in the PubMed, Cochrane Library, and EMBASE databases, identifying a total of 2182 documents, of which only 4 were included in the present review. The included studies had 148 participants (47 men and 101 women), with a minimum age of 53 and a maximum of 92 years, and supplementation times of 13 to 30 days (1 to 3 times a day). For the results, in relation to muscle performance, when comparing the control and experimental groups, greater muscle atrophy was observed in the pre- and post-moments of the control group, in relation to the experimental group. In addition, studies suggest a good tendency for muscle mass gain, and improvement in the functional capacities of patients who used supplementation. Therefore, the use of amino acids after TKA surgery reduces muscle atrophy, which preserves muscle mass and leads to better performance in tests of strength and functional capacity, when compared to the use of a placebo.

Pipkin Type-II Femoral Head Fracture - A Biomechanical Evaluation by the Finite-Element Method

Objective  To evaluate the biomechanical capacity of two forms of fixation for Pipkin type-II fractures, describing the vertical fracture deviation, the maximum and minimum principal stresses, and the Von Mises equivalent stress in the syntheses used. Materials and Methods  Two internal fasteners were developed to treat Pipkin type-II fractures through finite elements: a 3.5-mm cortical screw and a Herbert screw. Under the same conditions, the vertical fracture deviation, the maximum and minimum principal stresses, and the Von Mises equivalent stress in the syntheses used were evaluated. Results  The vertical displacements evaluated were of 1.5 mm and 0.5 mm. The maximum principal stress values obtained in the upper region of the femoral neck were of 9.7 KPa and 1.3 Kpa, and the minimum principal stress values obtained in the lower region of the femoral neck were of -8.7 KPa and -9.3 KPa. Finally, the peak values for Von Mises stress were of 7.2 GPa and 2.0 GPa for the fixation models with the use of the 3.5-mm cortical screw and the Herbert screw respectively. Conclusion  The fixation system with the Herbert screw generated the best results in terms of reduction of vertical displacement, distribution of the maximum principal stress, and the peak Von Mises equivalent stress, demonstrating mechanical superiority compared to that of the 3.5-mm cortical screw in the treatment of Pipkin type-II fractures.

Unilateral Versus Bilateral Resistance Exercise in Postoperative Rehabilitation After ACL Reconstruction With Bone-Patellar Tendon-Bone Graft: A Randomized Controlled Trial

Background

Lower limb muscle strength symmetry has been suggested as an essential criterion for the safe return to sports after anterior cruciate ligament (ACL) reconstruction. Limited evidence is available regarding the most effective intervention to achieve symmetry after reconstruction with contralateral bone-patellar tendon-bone (BPTB) graft.

Purpose

To verify whether unilateral isotonic resistance exercise is more effective than bilateral exercise for obtaining postoperative functional and muscular strength symmetry between the donor limb and reconstructed limb for patients who received BPTB graft.

Study Design

Randomized controlled trial; Level of evidence, 1.

Methods

A total of 88 patients were randomly divided into a control group (n = 44) and an intervention group (n = 44). All participants performed an 8-week exercise program starting at the beginning of the fourth postoperative month and were evaluated before and after the program. The control group performed bilateral exercises, and the intervention group performed unilateral exercises for the donor limb only (the limb with the greatest disability). The primary outcome was muscle strength (peak torque and hamstrings to quadriceps [H:Q] ratio), and the secondary outcomes were range of motion (ROM; goniometry), KT-1000 arthrometer side-to-side difference in anteroposterior knee laxity, and objective (single-leg hop test) and subjective (Lysholm score) functionality.

Results

Both groups improved significantly from before to after the exercise program. The improvements were significantly greater in the intervention group regarding peak torque, H:Q ratio, flexion ROM, single-leg hop test, and Lysholm score in the donor limb (P < .001 for all), and the improvements were significantly greater in the control group regarding peak torque and single-leg hop test in the reconstructed limb (P < .001 for both). Comparison between the groups showed significantly increased symmetry regarding peak torque, H:Q ratio, and single-leg hop test in the intervention group compared with the control group (P < .001), with large effect sizes (>0.80) except for the H:Q ratio.

Conclusion

Although postoperative, bilateral, isotonic resistance exercise provided better strength gains to the reconstructed limb, unilateral exercise was more effective in obtaining functional and muscle strength between-limb symmetry in patients who underwent ACL reconstruction with contralateral BPTB graft.

Registration

Brazilian Registry of Clinical Trials (number RBR-22rnjh).

Proposal for a New Fixation Method for Pauwels Type III Femoral Neck Fracture-Metaphyseal Stem: A Finite-Element Analysis

OBJECTIVE

To evaluate the biomechanical behavior of a metaphyseal stem specifically designed for the fixation of Pauwels type-III femoral neck fractures using finite-element analysis.

METHODS

Three different constructions were studied: the dynamic hip screw with a superior anti-rotation screw (DHS + ARS), multiple cannulated screws in an inverted triangle configuration (ASNIS), and the Metaphyseal Nailing System (MNS), a new implant developed by the authors. Vertical and total displacement, localized and total maximum and minimum principal, and the Von Mises peak stresses were evaluated.

RESULTS

Results are shown for the DHS + ARS, ASNIS, and MNS models, respectively. Vertical displacement (mm) was 1.49, 3.63, and 1.90; total displacement (mm) was: 5.33, 6.02, and 6.30; localized maximum principal (Mpa) was: 2.77, 4.5, and 1.7; Total maximum principal (Mpa) was: 126, 223, and 531; localized minimum principal (Mpa) was: -1.8, -3.15, and -0.39; total minimum (Mpa) was: -121, -449, and -245; and Von Mises peak stress (MPA) was: 315.5, 326.1, and 286.0.

CONCLUSION

The present FEM study showed that the MNS device increases general stresses and reduces localized stresses, when compared to the DHS + ARS and ASNIS constructions used to fix Pauwels type-III femoral neck fracture in synthetic models. In this sense, the MNS showed a low fracture focus shift, conducive to the consolidation environment. The significant reduction in the maximum principal stress, allows to affirm that the main deforming force, the shear, in this fracture pattern, was considerably reduced and the low value of Von Mises obtained, consistent with an implant capable of making an effective load sharing.

Effects of proprioceptive exercises and strengthening on pain and functionality for patellofemoral pain syndrome in women: A randomized controlled trial

OBJECTIVE

The objective of this study was to verify the effects of resisted and proprioceptive exercises program for the treatment of patients diagnosed with patellofemoral pain syndrome (PFPS).

DESIGN METHOD

Randomized Controlled Trial - level of evidence, II.

METHODS

Sixty female patients, clinically diagnosed with PFPS, were allocated into two experimental groups. The exercise group (ExG) underwent 6 weeks of a resisted and proprioceptive exercises for the trunk muscles, abductors and lateral hip rotators and knee extensors. The Guidance Group (GG) received educational, cognitive and behavioral guidance on healthcare. Before and after the program implementation period, all participants were evaluated in relation to the injured limb for pain assessment, subjective functionality, maximum isometric strength and 2D biomechanical analysis.

RESULTS

After a six-week follow-up, ExG showed significant improvement in the Numerical Pain Rating Scale, Anterior Knee Pain Scale and Knee Outcome Survey- Activities of Daily Living Scale when compared to the control group (p ≤ 0,05). The ExG also proved superior for increased muscle strength of knee extensors, hip abductors, decreased dynamic knee valgus and pelvic drop in relation to GG (p ≤ 0.05). However, when we consider the strength of the hip lateral rotator muscles there was no difference between the two interventions (p > 0.05).

CONCLUSION

Resisted and proprioceptive exercises yielded superior results to those of a treatment focused on educational, cognitive and behavioral guidance in improving pain and lower limb function for women with PFPS.

New fixation method for Pauwels type III femoral neck fracture: a finite element analysis of sliding hip screw, L-shaped, and L-shaped with medial plate

OBJECTIVE

In this study, we aimed to evaluate the biomechanical behavior of three fixations for Pauwels type III fractures (sliding hip screw (SHS), L-shaped, and L-shaped with medial plate), by finite element analysis (FEM).

METHODS

Three internal fixators were developed to treat Pauwels type III fracture by finite elements: SHS; L-shaped; and L-shaped with medial plate. Under the same conditions, localized and total vertical fracture displacement, maximum and minimum principal and von Mises stresses were evaluated.

RESULTS

The localized and total vertical displacement evaluated for the SHS, L-shaped, and L-shaped with medial plate were 0.15 mm, 0.17 mm, and 0.07 mm (localized), and 4.52 mm, 6.97 mm, and 6.83 mm (total), respectively. The maximum values obtained in the upper region of the femoral neck for the internal fixations were 1.43 MPa, 1.29 MPa, and 1.24 MPa, and the minimum values obtained in the lower region of the femoral neck were  - 0.73 MPa,  - 1.09 MPa, and  - 1.03 MPa, respectively. The maximum Von Mises peak stress values were 6.35 MPa, 10.7 MPa, and 16.2 MPa for the fixation models using the SHS, L-shaped, and L-shaped with medial plate, respectively.

CONCLUSION

The present FEM analysis showed that SHS yields better results in terms of total vertical displacements, maximum distribution, and Von Mises peak stresses reduction. On the other hand, the L-shaped construction plus a medial plate decreases localized vertical displacements and maximum principal distribution when compared to the SHS and L-shaped constructions. These results demonstrate that both constructions, SHS and L-shaped plus a medial plate, are biomechanically efficient for the fixation of Pauwels type III femoral neck fractures.

Calcaneal Tendon Plasticity Following Gastrocnemius Muscle Injury in Rat

Cross-talk between skeletal muscle and tendon is important for tissue homeostasis. Whereas the skeletal muscle response to tendon injury has been well-studied, to the best of our knowledge the tendon response to skeletal muscle injury has been neglected. Thus, we investigated calcaneal tendon extracellular matrix (ECM) remodeling after gastrocnemius muscle injury using a rat model. Wistar rats were randomly divided into four groups: control group (C; animals that were not exposed to muscle injury) and harvested at different time points post gastrocnemius muscle injury (3, 14, and 28 days) for gene expression, morphological, and biomechanical analyses. At 3 days post injury, we observed mRNA-level dysregulation of signaling pathways associated with collagen I accompanied with disrupted biomechanical properties. At 14 days post injury, we found reduced collagen content histologically accompanied by invasion of blood vessels into the tendon proper and an abundance of peritendinous sheath cells. Finally, at 28 days post injury, there were signs of recovery at the gene expression level including upregulation of transcription factors related to ECM synthesis, remodeling, and repair. At this time point, tendons also presented with increased peritendinous sheath cells, decreased adipose cells, higher Young’s modulus, and lower strain to failure compared to the uninjured controls and all post injury time points. In summary, we demonstrate that the calcaneal tendon undergoes extensive ECM remodeling in response to gastrocnemius muscle injury leading to altered functional properties in a rat model. Tendon plasticity in response to skeletal muscle injury merits further investigation to understand its physiological relevance and potential clinical implications.

Detraining and Anabolic-Androgenic Steroid Discontinuation Change Calcaneal Tendon Morphology

Several side effects of anabolic-androgenic steroid (AAS) administration associated with training are reported in the biomechanical properties of the calcaneal tendon (CT) of rats. Thus, the aim of the present study is to evaluate the effects of the detraining and discontinuation of AAS administration on the CT morphology of rats submitted to exercise in water. Animals were divided into two groups (20/group): (1) Immediately after training (IA), and (2) Six weeks of detraining and AAS discontinuation (6W). The IA group included four subgroups: Sedentary (S), Trained (T), Sedentary with AAS administration (SAAS), and trained with AAS administration (TAAS). The 6W group included four subgroups: Sedentary (6W-S), six weeks of detrained (6W-T), six weeks of sedentary with AAS discontinuation (6W-SAAS), and six weeks of detrained with AAS discontinuation (6W-TAAS). Data show significant reduction in adipose cells volume density (Vv%) in the distal CT in 6W-TAAS group, indicating that training can exert a positive effect on the tendon. The 6W-SAAS group exhibited increased adipose cells Vv% in the distal region, compared with the W6-S and W6-T groups. A decrease in tendon proper cells Vv% and in peritendinous sheath cells Vv% of proximal and distal regions was also observed. In 6W-TAAS group showed increase in adipose cells, blood vessels, peritendinous sheath cells, and tendon proper cells Vv% in the distal region of the CT. The vertical jumps in water were not able to protect CT regions from the negative effects of AAS discontinuation for six weeks. However, after detraining and AAS discontinuation, many protective factors of the mechanical load in the long-term could be observed.