Repair within the first 48 h in the treatment of acute Achilles tendon ruptures achieves the best biomechanical and histological outcomes

The impact of N-acetylcysteine on early periods of tendon healing: histopathologic, immunohistochemical, and biomechanical analysis in a rat model

PURPOSE

This study aimed to evaluate the early effects of N-acetylcysteine, which has antioxidant, inflame-modulatory, and cytoprotective properties, on tendon healing.

MATERIALS AND METHODS

Thirty-five male Wistar Hannover rats were divided into five groups: first-week treatment (Group 1T), first-week control (Group 1C), third-week treatment (Group 3T), third-week control (Group 3C), and native tendons (Group N). Bilateral Achilles tenotomy was performed on all rats except Group N. After tenotomy, 150 mg/kg N-acetylcysteine was administered daily intraperitoneally to treatment groups, while isotonic saline was given to the control groups. Tendons were evaluated histopathologically, immunohistochemically, and biomechanically after sacrifice in the first and third weeks.

RESULTS

No significant differences were observed in the first week (p > 0.05). Movin and Bonar scores (lower scores reflect improved histologic healing) were significantly lower in Group 3T than in Group 3C (p = 0.002). Collagen type-I/type-III ratios were higher in Group 3T compared to Group 3C (p = 0.001). Fmax (N) values were similar across Group 3T, Group 3C, and Group N (p = 0.772). However, cross-sectional areas (mm2) were significantly smaller in Group 3T than in Group 3C (p = 0.001), with the smallest areas observed in native tendons. Thus, tensile strength (MPa, load per unit area) and toughness (J/103 mm3, energy absorbed per unit volume) were significantly higher in Group 3T than in Group 3C (p = 0.001).

CONCLUSION

N-acetylcysteine supplied some improved results on early markers of tendon healing. Although our findings support the potential of NAC as a therapeutic adjunct in tendon injuries, further studies are needed to evaluate the long-term effects and underlying mechanisms.

Acute Achilles tendon ruptures between 2002-2021: sustained increased incidence, surgical decline and prolonged delay to surgery-a nationwide study of 53 688 ruptures in Sweden

Introduction

Given the lack of consensus on optimal treatment strategies for acute Achilles tendon rupture (ATR), understanding temporal trends, treatment choice and demographic characteristics is important. Previous research suggests increasing incidence with declining surgical treatment. Current trends in Sweden are not known.

Hypothesis/purpose

To assess how incidence rates, treatment trends and time from injury to surgery (TTS) of ATR have changed between 2002 and 2021 in Sweden, with particular attention to changes since 2012.

Study design

Descriptive epidemiology study.

Methods

We conducted a nationwide register-based study including all inpatients and outpatients ≥18 years of age with an ATR between 2002 and 2021 in Sweden.

Results

53 688 ATRs (78.5% men) were identified during the study period. 15 045 patients (81.5% men) were surgically treated within 30 days. The long-term incidence rate for ATR injury increased by 45%, from 28.8 in 2002 to 41.7 in 2021 per 100 000 person-years (p<0.0001). In the last 5 years of the study, there was a significant, continuing increase in ATR incidence by 21%, from 34.4 in 2017 to 41.7 in 2021 per 100 000 person-years (p<0.0001). The surgical incidence rates decreased from 13.4 to 6.0 per 100 000 person-years (p<0.0001). TTS increased from 0.6 days in 2002 to 5.1 in 2021 (p<0.0001).

Conclusion

The observed increase in incidence rates and decrease in surgical treatment of ATR emphasise the need for evidence-based treatment and rehabilitation protocols for non-operated patients of all ages. A significant increase in time from injury to surgery was observed throughout the study period.

Pioglitazone Antagonized the Effects of Advanced Glycation End Products on Achilles Tendon Healing and Improved the Recovery of Tendon Biomechanical Properties

Purpose

Advanced glycation end products (AGEs) often accumulate in the Achilles tendon during the course of diabetes. This study aims to determine the impact of AGEs on tendon repair and explore the role of pioglitazone in mitigating this impact.

Methods

Forty-eight male 8 week-old Sprague Dawley rats were selected in this study. After transection of Achilles tendon, the rats were randomly divided into four groups. The Achilles tendons of rats were injected with 1000 mmol/L D-ribose to elevate the content of AGEs within the tendons in two groups, the remaining two groups received injections of phosphate buffered saline (PBS) solution. Subsequently, the first two groups were respectively received oral administration of pioglitazone (20 mg/kg/day) and PBS. The remaining two groups were given the same treatment. The expression of the collagen-I, TNF-α, IL-6 of the repaired tendon were detected. The macroscopic, pathologic and biomechanical aspects of tendon healing were also evaluated.

Results

AGEs accumulation in tendon during the healing process increases the expression of inflammatory factors such as TNF-α and IL-6, leading to insufficient synthesis of collagen-I and delayed recovery of the tendon's tensile strength. Pioglitazone significantly attenuated the damage caused by AGEs to the tendon healing process, effectively improving the recovery of tendon tensile strength. Pioglitazone could not inhibit the generation of AGEs in the tissue and also had no impact on the normal healing process of the tendon.

Conclusions

Pioglitazone could prevent the deleterious impact of AGEs on the Achilles tendon healing and improve the biomechanical properties of the tendon.

Muscular and Tendon Degeneration after Achilles Rupture: New Insights into Future Repair Strategies

Achilles tendon rupture is a frequent injury with an increasing incidence. After clinical surgical repair, aimed at suturing the tendon stumps back into their original position, the repaired Achilles tendon is often plastically deformed and mechanically less strong than the pre-injured tissue, with muscle fatty degeneration contributing to function loss. Despite clinical outcomes, pre-clinical research has mainly focused on tendon structural repair, with a lack of knowledge regarding injury progression from tendon to muscle and its consequences on muscle degenerative/regenerative processes and function. Here, we characterize the morphological changes in the tendon, the myotendinous junction and muscle belly in a mouse model of Achilles tendon complete rupture, finding cellular and fatty infiltration, fibrotic tissue accumulation, muscle stem cell decline and collagen fiber disorganization. We use novel imaging technologies to accurately relate structural alterations in tendon fibers to pathological changes, which further explain the loss of muscle mechanical function after tendon rupture. The treatment of tendon injuries remains a challenge for orthopedics. Thus, the main goal of this study is to bridge the gap between clinicians’ knowledge and research to address the underlying pathophysiology of ruptured Achilles tendon and its consequences in the gastrocnemius. Such studies are necessary if current practices in regenerative medicine for Achilles tendon ruptures are to be improved.

Effect of muscle atrophy and fatty infiltration on mid-term clinical, and functional outcomes after Achilles tendon repair

OBJECTIVES

Muscle atrophy is one of the most common problems after Achilles tendon repair. The aim of this study was to evaluate the effect of gastrosoleus muscle atrophy and fatty infiltration on clinical, and functional outcomes after Achilles tendon repair.

MATERIAL AND METHODS

A total of 46 patients (mean age = 39.3 ± 7.4 years) who underwent open Achilles tendon repair were included in the study. During the clinical evaluation of muscle atrophy, ipsilateral and contralateral calf circumference (CC), maximum heel rise (HR), and ankle range of motion measurements were recorded. Functional outcomes were assessed via The Achilles tendon Total Rupture Score (ATRS), the American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, and the Leppilahti score. Muscle volume (MV), cross-sectional area (CSA), and percent of fatty infiltration (FI) were measured via magnetic image resonance.

RESULTS

The functional outcome scores were excellent: ATRS = 98.1 ± 2.2; AOFAS = 97.3 ± 4.1; Leppilahti score = 95.8 ± 5.1. There were significant differences detected between injured and non-injured legs regarding CC, HR, MV, CSA, and FI. Additionally, there were significant negative correlations between CSA and MV loss with all functional outcome scores. FI was correlated with only the AOFAS ankle-hindfoot score.

CONCLUSIONS

Significant muscle atrophy was measured after a mean follow-up period of 7.4 (range 2.0-12.6) years post-surgery and negatively correlated with clinical outcomes. CC is an easy and cost-effective measurement method to predict MV during the follow-up of Achilles tendon repairs.

Comparison of Large-Gauge Needle, Corneal Knife, and No. 11 Blade for Percutaneous Achillotomy

BACKGROUND

In the Ponseti technique, the residual equinus deformity is corrected with percutaneous tenotomy. This experimental study aimed to compare the safety and effectiveness of a large-gauge needle, a corneal knife, and a No. 11 blade in percutaneous achillotomy performed in rats.

METHODS

Ninety Achilles tendons of 45 Sprague-Dawley rats were analyzed, following division into three study groups. In the study, group I (needle), group II (corneal knife), and group III (No. 11 blade) were compared on the basis of bleeding, incision length, requirement for primary suture, range of motion, and resulting neurovascular injury at day 0. Moreover, the groups were compared in terms of range of motion, macroscopic and microscopic adhesions, and tenocyte morphology at days 21 and 42 postoperatively.

RESULTS

On day 0, one suture was required in group III, whereas in groups I and II, no sutures were required. Postoperative bleeding was greater in group III and similar in groups I and II. Neurovascular injury was not observed in any of the groups. Three incomplete tenotomies were observed in group III and one incomplete tenotomy was observed in group II. Importantly, all tenotomies were complete in group I. In all groups, the range of motion was similar. The macroscopic adhesion score revealed high adhesion in group III (P = .009). According to Tang's criteria, microscopic adhesion was significantly higher on day 21 in group III compared with the other groups (P <0.001). No significant differences were observed in tenocyte morphology based on the Bonar criteria (P = .850).

CONCLUSIONS

In the results obtained from this animal study, we observed less bleeding, less adhesion, and less incomplete tenotomy in the large-gauge needle and corneal knife groups compared with the No. 11 blade group during the percutaneous Achilles tenotomy performed in rats.

Effect of low intensity photobiomodulation associated with norbixin-based poly (hydroxybutyrate) membrane on post-tenotomy tendon repair. In vivo study

Purpose:

To evaluate the in vivo response of photobiomodulation therapy associated with norbixin-based poly(hydroxybutyrate) membrane (PHB) in tenotomized calcaneal tendon.

Methods:

Thirty rats were randomly allocated to six groups (n=5 each): LED groups (L1, L2 and L3) and membrane + LED groups (ML1, ML2 and ML3). The right calcaneal tendons of all animals were sectioned transversely and were irradiated with LED daily, one hour after surgery every 24 hours, until the day of euthanasia. At the end of the experiments the tendons were removed for histological analysis.

Results:

The histological analysis showed a significant reduction in inflammatory cells in the ML1, ML2 and ML3 groups (p=0.0056, p=0.0018 and p<0.0001, respectively) compared to those in the LED group. There was greater proliferation of fibroblasts in the ML1 (p<0.0001) and L3 (p<0.0001) groups. A higher concentration of type I collagen was also observed in the ML1 group (p=0.0043) replacing type III collagen.

Conclusion:

Photobiomodulation in association with norbixin-based PHB membrane led to control of the inflammatory process. However, it did not favor fibroblast proliferation and did not optimize type I collagen formation in the expected stage of the repair process.

Age and Tightness of Repair Are Predictors of Heel-Rise Height After Achilles Tendon Rupture

Background:

Achilles tendon rupture leads to weakness of ankle plantarflexion. Treatment of Achilles tendon rupture should aim to restore function while minimizing weakness and complications of management.

Purpose:

To determine the influence of factors (age, sex, body mass index [BMI], weight, time from injury to operative repair, and tightness of repair) in the initial surgical management of patients after an acute Achilles tendon rupture on 12-month functional outcome assessment after percutaneous and minimally invasive repair.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

From May 2012 to January 2018, patients sustaining an Achilles tendon rupture receiving operative repair were prospectively evaluated. Tightness of repair was quantified using the intraoperative Achilles tendon resting angle (ATRA). Heel-rise height index (HRHI) was used as the primary 12-month outcome variable. Secondary outcome measures included Achilles tendon total rupture score (ATRS) and Tegner score. Stepwise multiple regression was used to create a model to predict 12-month HRHI.

Results:

A total of 122 patients met the inclusion criteria for data analysis (mean ± SD age, 44.1 ± 10.8 years; 78% male; mean ± SD BMI, 28.1 ± 4.3 kg/m²). The elapsed time to surgery was 6.5 ± 4.0 days. At 12-month follow-up, patients had an HRHI of 82% ± 16% and performed 82% ± 17% of repetitions compared with the noninjured side. Participants had a mean ATRS of 87 ± 15 and a median Tegner score of 5 (range, 1-9), with a reduction in Tegner score of 2 from preinjury levels. The relative ATRA at 12 months was –4.8° ± 3.9°. Multiple regression identified younger age (B = ±0.006; P < .001) and greater intraoperative ATRA (B = 0.005; P = .053) as predictors of more symmetrical 12-month HRHI (R² = 0.19; P < .001; n = 120).

Conclusion:

Age was found to be the strongest predictor of outcome after Achilles tendon rupture. The most important modifiable risk factor was the tightness of repair. It is recommended that repair be performed as tight as possible to optimize heel-rise height 1 year after Achilles tendon rupture and possibly to reduce tendon elongation.