Biochemistry and biomechanics of healing tendon: Part I. Effects of rigid plaster casts and functional casts

Comparing Surgical and Conservative Treatment on Achilles Tendon Rupture: A Comprehensive Meta-Analysis of RCTs

Background: The Achilles tendon is the strongest tendon in human and is frequently injured, mainly in the young to middle age active population. Increasing incidence of Achilles tendon rupture (ATR) is still reported in several studies. Surgical repair and conservative treatment are two major management strategies widely adopted in ATR patients, but the consensus of the optimal treatment strategy is still debated. We aimed at thoroughly reviewing the ATR topic with additional assessments and performed a most comprehensive meta-analysis of randomized controlled trials (RCTs). Method: We comprehensively searched PubMed, Embase, Cochrane, and ClinicalTrial.gov and retrieved all RCTs comparing surgical and conservative treatment on ATR for further analysis. Two independent reviewers performed data extraction and random effect model was adopted when I 2 > 50%, with data presentation of risk ratio, risk difference, or mean difference and 95% confidence interval. Results: A total of 13 RCTs were included in this meta-analysis. A significant difference was observed in re-rupture, complication rate, adhesion to the underlying tendon, sural nerve injury, and superficial infection. A substantial reduction in re-rupture rate could be observed for surgical treatment while the complication rate was higher compared with conservative treatment. Conclusion: Surgical treatment revealed significance in reducing the re-rupture rate but was associated with a higher complication rate, while conservative treatment showed similar outcomes with a lower complication rate. Collectively, we recommend conservative treatment if patients' status and expectations are suitable, but surgeon and physician discretion is also crucial in decision making.

Effects of immobilization and whole-body vibration on rat serum Type I collagen turnover

Objective

The aim of this study was to investigate the effects of short-term, high-magnitude whole-body vibration (WBV) on serum type I collagen turnover in immobilized rats.

Materials and Methods

Thirty Wistar albino rats were randomly divided into the following 5 groups: immobilization (IS), immobilization + remobilization (IR), immobilization + WBV (IV), control (C), and WBV control (CV). Immobilization was achieved by casting from the crista iliaca anterior superior to the lower part of the foot for 2 weeks. The applied WBV protocol involved a frequency of 45 Hz and amplitude of 3 mm for 7 days starting a day after the end of the immobilization period. Serum type I collagen turnover markers were measured by using ELISA kits.

Results

Serum NH2-terminal propeptide of type I collagen (PINP) levels were significantly lower in the immobilization groups (p < 0.02) compared with the control groups. Although WBV improved PINP levels in the control groups, there were no differences in PINP levels among the immobilization groups. Similarly, serum COOH-terminal telopeptide of type I collagen (CTX) levels were higher in the WBV controls than their own controls (p < 0,05). Immobilization led to deterioration of tendon tissue, as observed by histopathological analysis with a transmission electron microscope.

Conclusion

Although 1 week of WBV had a positive effect on type I collagen turnover in controls, it is not an efficient method for repairing tissue damage in the early stage following immobilization.

Early functional rehabilitation or cast immobilisation for the postoperative management of acute Achilles tendon rupture? A systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To determine which postoperative rehabilitation regime is superior following surgical repair of acute Achilles tendon rupture. The primary outcomes were patient safety and satisfaction.

DESIGN

Intervention meta-analysis.

DATA SOURCES

The MEDLINE and CINAHL electronic databases were searched from their date of inception until June 2015 using keywords related to acute Achilles tendon rupture, surgical repair and rehabilitation. The electronic database search was supplemented with forward citation tracking using the Web of Science.

ELIGIBILITY CRITERIA

Randomised controlled trials comparing clinical and/or patient-reported outcomes between patients receiving early functional postoperative ankle motion and weight bearing (bracing group), and traditional ankle immobilisation with a non-weight bearing rigid cast (cast group) were eligible for inclusion. Fourteen articles were identified as potentially eligible; 10 sufficient-quality randomised controlled trials involving 570 patients were included for meta-analysis.

MAIN RESULTS

A high proportion of patients were able to return to prior employment and sporting activity in both groups. Five of the six trials measuring the time interval showed a faster return to prior sporting level in the bracing group. Subjective patient outcomes were significantly better in the bracing group (for good and excellent results, p=0.01; OR, 3.13; 95% CI 1.30 to 7.53). There was no difference in major complications between the two groups (p=0.21; RD, -0.03; 95% CI -0.06 to 0.01). Dynamometry and anthropometry measurements favoured functional rehabilitation at 6-12 weeks postoperation; however, by 6 months postoperative, the differences were negligible.

CONCLUSIONS

Compared to traditional ankle immobilisation, with a non-weight bearing cast following surgical repair of acute Achilles tendon rupture, early dynamic functional rehabilitation is as safe with higher patient satisfaction.

Different power settings of LLLT on the repair of the calcaneal tendon

OBJECTIVE

The purpose of this study was to evaluate the effect of an 830-nm GaAlAs diode laser operating at output powers of 40, 60, 80, and 100 mW and energy density of 30 J/cm(2) on the repair of partial calcaneal tendon ruptures in rats.

METHODS

A partial tendon rupture was induced in all animals, which were treated with laser irradiation for 5 consecutive days. Six days after injury, the injured tendons were removed and examined by polarized light microscopy. Collagen fiber organization was evaluated by birefringence measurements, and collagen content was determined by Picrosirius Red staining.

RESULTS

It was observed that the higher the output power (60-100 mW) the greater the amount of type III collagen (p<0.01). The amount of type I collagen was significantly greater (p=0.05) in the 80 mW group than in the control group (sham stimulation). A non-statistically significant improvement in the realignment of collagen fibers was observed in the irradiated groups.

CONCLUSIONS

Low-level laser therapy resulted in significantly greater amounts of type III collagen (output powers of 60 mW or more) and type I collagen (output power of 80 mW), however, no significant differences between groups were found in the realignment of collagen fibers.

Achilles tendon rehabilitation

The operative management of acute Achilles tendon rupture marks the beginning of a comprehensive rehabilitation program. The goals of the rehabilitation program start with the reduction of pain and swelling and the recovery of ankle motion and power. They conclude with the restoration of coordinated activity and safe return to athletic activity. The rehabilitation protocol is directed by the injury and the quality of the repair, along with the patient's age, medical and social history, and athletic inclination. The protocol is dynamic and responsive to changing clinical findings.

The influence of training status on the drop in muscle strength after acute exercise

Skeletal muscles fatigue after exercise, and reductions in maximal force appear. A difference in training status between the legs was introduced by unilateral immobilization of the calf muscles for 2 weeks in young men, who were randomly assigned to two groups, either a RUN group (n = 8) that was exposed to prolonged exercise (1-h running: individual pace) or a REST group (n = 12) that did no exercise after immobilization. Cross-sectional area (CSA) of the triceps-surae muscles was calculated by magnetic resonance imaging (MRI), and maximal voluntary contraction (MVC) force of the plantar flexors was measured before and after immobilization and after the running protocol. The CSA of triceps-surae muscles decreased significantly with a 7% reduction in both groups. A significant drop in the MVC of the triceps-surae muscle (10%; P < 0.05) was observed in response to immobilization. When subjected to running exercise immediately after immobilization, the muscle strength of the triceps-surae muscles dropped even further, but just in the immobilized leg (41%; P < 0.05). The present study highlights the importance of determining the muscle endurance when evaluating the effect of immobilization on muscle parameters.

Short-term immobilization and recovery affect skeletal muscle but not collagen tissue turnover in humans

Not much is known about the effects of immobilization and subsequent recovery on tendon connective tissue. In the present study, healthy young men had their nondominant leg immobilized for a 2-wk period, followed by a recovery period of the same length. Immobilization resulted in a mean decrease of 6% (5,413 to 5,077 mm(2)) in cross-sectional area (CSA) of the triceps surae muscles and a mean decrease of 9% (261 to 238 N.m) in strength of the immobilized calf muscles. Two weeks of recovery resulted in a 6% increased in CSA (to 5,367 mm(2)), whereas strength remained suppressed (240 N.m). No difference in Achilles tendon CSA was detected between the two legs at any time point. Local tendon collagen synthesis, measured as the peritendinous concentrations of PINP (NH(2)-terminal propeptide of type I collagen; indirect marker for collagen synthesis), was unchanged after 2 wk of immobilization. However, peritendinous levels of PINP were significantly elevated in the immobilized leg (15 to 139 ng/ml) following 2 wk of remobilization compared with preimmobilization levels. In contradiction hereto, systemic concentrations of PINP remained unchanged throughout the study. Immobilization reduced muscle size and strength, while tendon size and collagen turnover were unchanged. While recovery resulted in an increase in muscle size, strength was unchanged. No significant difference in tendon size could be detected between the two legs after 2 wk of recovery, although collagen synthesis was increased in the previously immobilized leg. Thus 2 wk of immobilization are sufficient to induce significant changes in muscle tissue, whereas tendon tissue seems to be more resistant to short-term immobilization.

Static and dynamic biomechanical properties of the regenerating rabbit Achilles tendon

BACKGROUND

Since tendons show viscoelastic behavior, dynamic viscoelastic properties should be assessed in addition to static biomechanical properties. We evaluated differences between static and dynamic biomechanical properties of the regenerating rabbit Achilles tendon following tenotomy.

METHODS

At 3, 6, or 12 weeks after right Achilles tenotomy, the right (regenerating) and left (control) tendons were collected with the calcaneus from 49 rabbits. A unidirectional failure test and a dynamic viscoelastic test were conducted.

FINDINGS

Tensile strength and Young's modulus (static biomechanical properties) in the regenerating group at Week 6 were significantly greater than at Week 3, while at Week 12, these were significantly greater than at Week 6. However, even at Week 12, both parameters were less than in the control group. The value of tan delta represents dynamic viscoelasticity, a smaller tan delta indicates greater elasticity. tan delta for the regenerating group was significantly greater than for the control group at Week 3, but regenerating and control groups did not significantly differ at Week 6. No marked change was seen from Weeks 6 to 12 in the regenerating group, and no significant difference in tan delta was evident between the regenerating and control groups at Week 12.

INTERPRETATION

Dynamic biomechanical properties of regenerating rabbit Achilles tendons may improve more rapidly than static biomechanical properties. Ability to tolerate dynamic movement in the healing Achilles tendon may improve more rapidly than ability to withstand static stresses.

Extracellular matrix of porcine pericardium: biochemistry and collagen architecture

Pericardial tissue has been used to construct bioprostheses employed in the repair of different kinds of injuries, mostly cardiac. However, calcification and mechanical failure have been the main causes of the limited durability of cardiac bioprostheses constructed with bovine pericardium. In the course of this work, a study was conducted on porcine fibrous pericardium, its microscopic structure and biochemical nature. The general morphology and architecture of collagen were studied under conventional light and polarized light microscopy. The biochemical study of the pericardial matrix was conducted according to the following procedures: swelling test, hydroxyproline and collagen dosage, quantification of amino acids in soluble collagen, component extraction of the extracellular matrix of the right and left ventral regions of pericardium with different molarities of guanidine chloride, protein and glycosaminoglycan (GAG) dosage, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and total GAG analysis. Microscopic analysis showed collagen fibers arranged in multidirectionally oriented layers forming a closely knit web, with a larger number of fibers obliquely oriented, initiating at the lower central region toward the upper left lateral relative to the heart. No qualitative differences were found between proteins extracted from the right and left regions. Likewise, no differences were found between fresh and frozen material. Protein dosages from left frontal and right frontal pericardium regions showed no significant differences. The quantities of extracted GAGs were too small for detection by the method used. Enzymatic digestion and electrophoretic analysis showed that the GAG found is possibly dermatan sulfate. The proteoglycan showed a running standard very similar to the small proteoglycan decorin.

SURGICAL REPAIR FOLLOWED BY FUNCTIONAL REHABILITATION FOR ACUTE AND CHRONIC ACHILLES TENDON INJURIES: EXCELLENT FUNCTIONAL RESULTS, PATIENT SATISFACTION AND NO RERUPTURES

BACKGROUND

We evaluated 46 patients who underwent surgical repair of the Achilles tendon at our institution during a 4.5-year period, followed by early weight bearing, aiming to assess their return to activities, rerupture rate and satisfaction.

METHODS

A cohort of 46 patients who underwent Achilles tendon repair at our institution during a 4.5-year period, with a modified triple mini-Becker suture technique, for both acute as well as chronic Achilles tendon ruptures were studied. These patients were reviewed at a minimum of 2.5 years follow up (average 4.5 years ranging from 2.5 to 6.5 years), by chart review and questionnaire, to determine the functional outcome as well as patient satisfaction following an active postoperative protocol involving full weight-bearing ambulation in a controlled ankle motion walker and active stretching, followed by a graduated strengthening programme.

RESULTS

We found a very high level of satisfaction, with few minor complications and no reruptures in either the early or the delayed repair groups.

CONCLUSION

We believe that surgical repair using this technique associated with an early return to protected full weight-bearing ambulation and an active early rehabilitation programme provides not only excellent functional results, patient satisfaction and a zero rerupture rate, but also much less morbidity in the first 3 months and a quicker overall recovery compared with non-operative treatment.

The effect of variations in applied rehabilitation force on collagen concentration and maturation at the intrasynovial flexor tendon repair site

The biochemical means by which accelerated rehabilitation alters intrasynovial flexor tendon repair site collagen synthesis and extracellular matrix maturation are not fully understood. We hypothesized that an increased level of applied rehabilitative force in a clinically relevant animal model would hasten the maturation of the repair site extracellular matrix as demonstrated by total collagen and collagen cross-link assessment. Twenty-eight flexor digitorum profundus tendons from 14 adult dogs were transected and repaired. The animals received either low- or high-force rehabilitation and were killed 10, 21, and 42 days after surgery. A 10-mm segment of tendon surrounding the repair site was obtained. Biochemical analysis showed that total collagen concentration was significantly reduced at each time point, that the reducible cross-link ratio of dihydroxylysinonorleucine to hydroxylysinonorleucine was significantly increased at each time point, and that the nonreducible pyridinoline cross-link content was significantly decreased at 10 days in both rehabilitative groups. Total collagen content did not vary to a statistically significant degree with either time or as a function of rehabilitation type. Based on these findings several clinically relevant observations can be made. Increasing collagen concentration and repair site maturation do not explain the previously demonstrated increased tensile properties of tendon that occur between 3 and 6 weeks after repair. Higher force rehabilitation does not alter the biochemical composition of the healing tendon through 6 weeks. Coupled with other recent data these findings suggest that high-force rehabilitation does not stimulate accelerated healing after intrasynovial flexor tendon repair.

The semitendinosus tendon regenerates after resection: a morphologic and MRI analysis in 6 patients after resection for anterior cruciate ligament reconstruction

Recently, the surprising observation has been made, supported by clinical and MRI findings, that the semitendinosus tendon can regenerate after being harvested in its whole length and thickness for anterior cruciate ligament reconstruction. We studied 6 patients with previous anterior cruciate ligament reconstruction, using a quadruple semitendinosus tendon autograft. In 5 of these, physical examination and MRI showed that the tendond had regenerated. In all 6 patients, the findings were documented macroscopically by open surgical exploration and in the 5 regenerated tendons, also morphologically by biopsies. Macroscopically, histologically and immunohistochemically the regenerated tendons closely resembled normal ones with focal scar-like areas. Our present findings and earlier studies show that full length and thickness harvesting of the semitendinosus tendon in most cases result in full-length tendon regeneration with tissue closely resembling the normal tendon.