Correlation between change in muscle excursion and collagen content after tendon rupture and delayed repair

Changes in passive hamstring stiffness after primary anterior cruciate ligament reconstruction: A prospective study with comparison of healthy controls

BACKGROUND

The mechanical properties of knee flexors muscles contribute to reducing anterior cruciate ligament loading. This case-control study evaluated the passive knee flexors stiffness after primary anterior cruciate ligament reconstruction with comparison of healthy controls.

METHODS

After anterior cruciate ligament reconstruction, 88 participants (24.5 [8.6] years, 56,8% males) had two isokinetic tests at 4 and 8 postoperative months with measurement of the passive resistive torque of knee flexors and extensors/flexors strength. In the control group, 44 participants (24.5 [4.3] years, 56,8% males) had one visit with the same procedures. Passive knee flexors stiffness was calculated as the slope of the passive torque-angle curve on the last 10° of knee extension (Nm/°). We investigated the impact of timing and type of surgery (autograft and combined meniscus repair) and persistent knee extension deficits on knee flexors stiffness.

FINDINGS

At 4 and 8 postoperative months, passive knee flexors stiffness was lower on the operated limb than on the non-operated limb (P < 0.001) but both limbs had significant lower values than controls (P < 0.001). Stiffness was positively correlated with knee flexors strength (P < 0.010), and knee flexors stiffness at 4 months was lower in individuals who underwent surgery <6 months from injury (P = 0.040). Knee extension deficit or the type of surgery did not have a significant influence on knee flexors stiffness.

INTERPRETATION

Similarly to neuromuscular factors that are traditionally altered after anterior cruciate ligament reconstruction, evaluating passive knee flexors stiffness changes over time could provide supplementary insights into postoperative muscle recovery.

Wide-Awake Local Anesthesia No Tourniquet Surgery for Zone VII Extensor Tendon Reconstruction: Stages in Active Range of Motion From Intraoperative to Final Recovery

PURPOSE

We investigated chronological changes in active range of motion (ROM) of the metacarpophalangeal (MCP) joint after zone VII extensor tendon reconstruction with wide-awake local anesthesia no tourniquet (WALANT) surgery.

METHODS

Reconstruction of the extensor tendons ruptured in zone VII of 82 fingers in 40 patients was performed using WALANT techniques. The mean patient age was 71.3 years. During surgery, we evaluated passive stretch distance and active contraction distance of the ruptured musculocutaneous unit. The sum of passive stretch distance and active contraction distance was defined as total excursion. In cases with total excursion ≥30 mm, we selected bridge tendon grafting for tendon reconstruction. In cases with total excursion <30 mm, end-to-side tendon transfer was performed. Active ROM of the MCP joint was measured before surgery; during surgery; 1, 3, and 5 months after surgery, and at the final follow-up.

RESULTS

Extension lag of the MCP joint was 49.2° before surgery, improving to 2.9° during surgery, deteriorating to 18.7° at 1-month, and improving again to 15.6° at 3-months, 13.6° at 5-months, and 10.5° at the final follow-up. Meanwhile, the active flexion angle of the MCP was 87.9° before surgery, 87.3° during surgery, 67.6° at 1-month, 76.0° at 3-months, 79.7° at 5-months, and 81.0° at the final follow-up. Extension and flexion angles at each time point remained nearly constant regardless of whether tendon grafting or tendon transfer was used.

CONCLUSIONS

Extensor tendon reconstruction using WALANT surgery allowed intraoperative measurement of active ROM, confirming near-complete extension and flexion after reconstruction. The changes in ROM of the MCP joint during follow-up are an approximate indication of the progression of postoperative recovery.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic Ⅳ.

Changes in tendon length and excursion following extensor tendon grafting at the distal radioulnar joint

IV.

FGF gene expression in injured tendons as a prognostic biomarker of 1-year patient outcome after Achilles tendon repair

PURPOSE

Healing outcome after Achilles Tendon Rupture (ATR) is variable and unsatisfactory. Many ATR patients still exhibit pain, functional deficits and limitations in walking one-year post-surgery. The present study was designed to investigate the association between the expression of healing biomarkers and patient outcome after ATR.

METHODS

Tendon biopsies were collected from 25 ATR patients during surgery. At 1-year post surgery, all patients completed questionnaires; Achilles tendon Total Rupture Score (ATRS) and Foot and Ankle Outcome Score (FAOS), and were tested for functional outcomes by heel-rise test. In biopsies, FGF, COL III, FN, COL I and MMP-9 mRNA levels were assessed by quantitative RT-PCR while protein expression was studied by immunohistochemistry (IHC).

RESULTS

Our analysis confirmed the presence of FGF, COL III, FN, COL I and MMP-9 at mRNA and protein levels in tendon biopsies. FGF gene expression associated positively with improved total ATRS and better functional outcomes. Additionally, FGF mRNA levels were associated with less pain, less running limitations and less loss in physical activity. In addition, higher COL III mRNA expression was associated with more tendon strength.

CONCLUSION

Our findings indicate that FGF gene expression is associated with improved patient-reported outcome. FGF expression in surgical biopsies could potentially be used to assist the prognostic evaluation of patient outcome and may be used as a predictor for healing. However, further studies are needed to evaluate the role of FGF in Achilles tendon healing.

LEVEL OF EVIDENCE

II.

Signature molecular changes in the skeletal muscle of hindlimb unloaded mice

Hind-limb unloaded (HU) mouse is a well-recognized model of muscle atrophy; however, the molecular changes in the skeletal muscle during unloading are poorly characterized. We have used Raman spectroscopy to evaluate the structure and behavior of signature molecules involved in regulating muscle structural and functional health. The Raman spectroscopic analysis of gastrocnemius muscles was compared between 16-18 weeks old HU c57Bl/6J mice and ground-based controls. The spectra showed that the signals for asparagine and glutamine were reduced in HU mice, possibly indicating increased catabolism. The peaks for hydroxyproline and proline were split, pointing towards molecular breakdown and reduced tendon repair. We also report a consistently increased intensity in> 1300 cm-1 range in the Raman spectra along with a shift towards higher frequencies in the HU mice, indicating activation of sarcoplasmic reticulum (SR) stress during HU.

Proteomics identifies differences in fibrotic potential of extracellular vesicles from human tendon and muscle fibroblasts

Background

Fibroblasts are the powerhouses responsible for the production and assembly of extracellular matrix (ECM). Their activity needs to be tightly controlled especially within the musculoskeletal system, where changes to ECM composition affect force transmission and mechanical loading that are required for effective movement of the body. Extracellular vesicles (EVs) are a mode of cell-cell communication within and between tissues, which has been largely characterised in cancer. However, it is unclear what the role of healthy fibroblast-derived EVs is during tissue homeostasis.

Methods

Here, we performed proteomic analysis of small EVs derived from primary human muscle and tendon cells to identify the potential functions of healthy fibroblast-derived EVs.

Results

Mass spectrometry-based proteomics revealed comprehensive profiles for small EVs released from healthy human fibroblasts from different tissues. We found that fibroblast-derived EVs were more similar than EVs from differentiating myoblasts, but there were significant differences between tendon fibroblast and muscle fibroblast EVs. Small EVs from tendon fibroblasts contained higher levels of proteins that support ECM synthesis, including TGFβ1, and muscle fibroblast EVs contained proteins that support myofiber function and components of the skeletal muscle matrix.

Conclusions

Our data demonstrates a marked heterogeneity among healthy fibroblast-derived EVs, indicating shared tasks between EVs of skeletal muscle myoblasts and fibroblasts, whereas tendon fibroblast EVs could play a fibrotic role in human tendon tissue. These findings suggest an important role for EVs in tissue homeostasis of both tendon and skeletal muscle in humans.

Exploring the Pathological Role of Collagen in Paravertebral Muscle in the Progression of Idiopathic Scoliosis

BACKGROUND

Paravertebral muscle (PVM) is considered as a contributing factor of idiopathic scoliosis (IS); collagen is crucial for maintaining the mechanical properties of PVM, but only a few researches have described this field. In this study, we observed the muscle stiffness of PVM and the curvature of the spine by adjusting the content of collagen in PVM of rats and explored the role of collagen in the progression of IS.

METHODS

32 female Sprague Dawley rats were randomly divided into four groups: neutralizing antibody (NA) group (group 1), normal control group (group 2), IS group (group 3), and IS with NA group (group 4). TGF-β1 NA was injected into PVM in group 1 and group 4, while Normal saline in group 2 and group 3. The Cobb angle and muscle stiffness were measured before and after injection; the rats were sacrificed at one week after injection, and performed histological, Western Blot, and qRT-PCR examinations.

RESULTS

X-rays showed that scoliosis occurred in group 1 and relieved in group 4. The stiffness of PVM was decreased significantly on the convex side in group 1, while on the concave side in group 4. The expression of TGF-β1 and COL1 on the concave side in IS rats (group 3) was significantly increased than that in normal rats (group 2), the concentration of COL1 and COL3 in group 3 was significantly higher than that in group 2, and the addition of TGF-β1 NA significantly downregulated COL1 and COL3 in group 1 and group 4. The concentration of COL1 in convex PVM was negatively related to Cobb angle in group 1 and group 2, and in concave PVM was positively related to Cobb angle in group 3 and group 4. However, no significant correlation was found between COL3 and Cobb angle in group 3 and group 4.

CONCLUSIONS

Asymmetric biomechanical characteristics of PVM was an important etiological factor of IS, which was directly correlated with collagen, it could be adjusted by local intramuscular injecting of TGF-β1 NA, and finally had an effect on the shape of the spine.

Tendon split lengthening technique for flexor hallucis longus tendon rupture

Background

Flexor hallucis longus (FHL) tendon rupture is a challenging injury to lead with clawing of the great toe when the FHL tendon is repaired too tight. When the diagnosis is delayed, the tendon ends may not be opposable because of contracture or poor tendon tissue.

Methods

A technique to reconstruct FHL tendon rupture without a free tendon graft is described. A split tendon lengthening is performed at the midfoot around the knot of Henry. Ankle block anesthesia is used to allow the patient’s active movement of the interphalangeal (IP) joint to determine the appropriate length of the reconstructed tendon for maintaining balance and preventing the tendon from being too tight or too loose. Between May 2012 and September 2015, five patients with a total rupture of the FHL tendon, having tendon defect distal to the knot of Henry, were treated with split tendon lengthening.

Results

Four patients could actively plantarflex the great toe IP joint. One patient who was operated under spinal anesthesia could not actively plantarflex the great toe IP joint, but did not have extension deformity and did not want another procedure. The mean American Orthopedic Foot and Ankle Society (AOFAS) score at a mean follow-up of 44 months was 92 points (range, 80–100).

Conclusions

This technique is described to overcome the difficulty of reconstructing the FHL tendon with tendon defect. The tendon defect could be repaired after split tendon lengthening without a free tendon graft.