Augmented repair of acute Achilles tendon ruptures using gastrocnemius-soleus fascia

Comparison between primary repair and augmented repair with gastrocnemius turn-down flap for acute Achilles tendon rupture: a retrospective study with minimum 2-year follow-up

BACKGROUND

To explore and compare the clinical outcomes in patients undergoing primary repair versus augmented repair with a gastrocnemius turn-down flap for acute Achilles tendon rupture.

METHODS

From 2012 to 2018, the clinical data of 113 patients with acute Achilles tendon rupture who were treated with primary repair or augmented repair with a gastrocnemius turn-down flap by the same surgeon were retrospectively reviewed. The patients' preoperative and postoperative scores on the visual analog scale (VAS), American Orthopaedic Foot and Ankle Society Ankle⁃Hindfoot (AOFAS) score, the Victorian Institute of Sport Assessment⁃Achilles (VISA-A), the Achilles tendon total rupture score (ATRS), and the Tegner Activity Scale were examined and compared. The postoperative calf circumference was measured. A Biodex isokinetic dynamometer was used to evaluate the plantarflexion strength on both sides. The time to return to life and exercise as well as the strength deficits in both groups were recorded. Finally, the correlation analyses between patient characteristics and treatment details with clinical outcomes were conducted.

RESULTS

In total, 68 patients were included and completed the follow-up. The 42 and 26 patients who were treated with primary repair and augmented repair were assigned to group A and B, respectively. No serious postoperative complications were reported. No significant between-group differences in any outcomes were observed. It was found that female sex was correlated with poorer VISA-A score (P = 0.009), complete seal of paratenon was correlated with higher AOFAS score (P = 0.031), and short leg cast was correlated with higher ATRS score (P = 0.006).

CONCLUSIONS

Augmented repair with a gastrocnemius turn-down flap provided no advantage over primary repair for the treatment of acute Achilles tendon rupture. After surgical treatment, females tended to had poorer outcomes, while complete seal of paratenon and short leg cast contributed to better results.

LEVEL OF EVIDENCE

Cohort study; Level of evidence, 3.

Arthroscopic Flexor Halluces Longus Transfer and Percutaneous Achilles Tendon Repair for Distal Traumatic Ruptures

The Achilles tendon is the largest and strongest tendon in the human body. It is the tendon that most often suffers injury and accounts for 20% of all tendon ruptures. These types of ruptures often occur 2 to 6 cm proximal to the stumps in an area of reduced vascularity. One such injury, the distal acute Achilles tendon rupture, is quite uncommon. For distal repairs, there have been studies that used a pullout technique, a button technique, and the use of local tendons for open-fashion augmentation. Although percutaneous repair and endoscopic flexor hallucis longus (FHL) tendon transfer techniques have been described for both acute midportion and chronic Achilles tendon rupture repair, there are no studies that describe the use of percutaneous sutures and biological augmentation with FHL transfer as a treatment option for acute distal injuries. The purpose of this Technical Note is to describe a novel approach to repair. It combines arthroscopic FHL tendon transfer with a percutaneous Achilles tendon repair technique for traumatic distal ruptures.

Augmented Repair of Acute Total Achilles Tendon Rupture With Peroneus Brevis Tendon Transfer Using Oblique Transosseous Calcaneal Tunnel: A Prospective Case Series

Acute Achilles tendon rupture is one of the most common tendon injuries. This prospective study aimed to evaluate the functional outcomes of augmented repair of acute Achilles tendon rupture with peroneus brevis tendon transfer and fixation to an oblique calcaneal transosseous tunnel. Functional evaluation was performed using the American Orthopaedic Foot & Ankle Society (AOFAS) score and Achilles Tendon Total Rupture Score (ATRS). Postoperative complications were recorded. This study included 33 males and 9 females, with a mean age of 26.1 ± 4.2 years. The Achilles tendon ruptures were right in 24 patients and left in 18 patients. The cause of rupture was sports injuries in all patients. The mean distance from the calcaneal insertion to the tear site was 4.4 ± 1.3 cm. The mean time from injury to surgery was 2.4 ± 1.6 days. The mean follow-up time was 40.3 ± 4.9 months. The mean AOFAS and ATRS scores were 99.3 ± 1.2 and 95.9 ± 1.9, respectively, at 12 months of follow-up. The mean time to return to work was 12.1 ± 1.2 weeks. The mean time to return to light sports activities was 16.1 ± 1.8 weeks postoperatively. None of the patients developed re-rupture. Augmented repair of acute Achilles tendon ruptures with peroneus brevis tendon transfer is a robust repair with excellent functional outcomes and early weight-bearing and return to sports activities.

Bilateral giant cell tumor of tendo Achilles: A case series on reconstruction by peroneus brevis - tibialis posterior tendon

Giant cell tumor of tendon sheath usually is localized painless solitary benign swelling, which presents as a firm nodular gradually growing mass. Giant cell tumor is infrequent in the lower limb and its incidence in the tendo Achilles is rare. It is often diagnosed and treated conservatively as tendinitis in the initial stages. The slow growth and limited functional deficit is the reason for its late presentation where excision of the mass leaves a large residual defect, for which reconstruction of the tendo Achilles has to be done by mobilizing different tendons. A case series of bilateral giant cell tumor of tendo Achilles and study the functional outcome of the reconstructed tendo Achilles using peroneus brevis - tibialis posterior tendons - are presented. The outcome of reconstruction using peroneus brevis - tibialis posterior tendon gave satisfactory outcome at the end of one year. LEVEL OF EVIDENCE: Level 4.

Composite sural neurocutaneous flap with gastrocnemius tendon for repairing defects of Achilles tendon and overlying soft tissue

PURPOSE

Defect of Achilles tendon and overlying soft tissue remains a surgical challenge due to its insufficient blood supply and high requirement of function. This study aims to report the clinical efficacy of the composite sural neurocutaneous composite flap with gastrocnemius tendon on the complicated defect of Achilles region.

METHODS

Seven cases of defects of Achilles tendon and overlying soft tissue were reconstructed by the composite sural neurocutaneous composite flaps with gastrocnemius tendons. It is important to keep the connection between gastrocnemius tendon and deep fascia of the composite flap during operation. The smallest and the largest areas of transferred skin flaps were 7.5 cm × 4.5 cm and 11 cm × 10 cm respectively. The size of gastrocnemius tendon ranged from 5 cm × 3 cm to 9 cm × 4 cm. Patients was evaluated by using the Arner-Lindholm scale at the last follow-up.

RESULTS

Six flaps survived completely with no complication. One flap developed wound dehiscence and went on to heal by daily dressing. With 12-60 months follow-up, all patients gained satisfactory appearance and function of ankle, without tendon re-rupture or recurrent infection. Based on Arner-Lindholm scale, six cases were noted to be excellent and one was good.

CONCLUSION

The composite sural neurocutaneous flap with gastrocnemius tendon is a viable and practical method to salvage Achilles tendon defect and overlying soft tissue coverage, with minimal adhesion and satisfactory function.

Results of Surgical Management of Achilles Tendon Rupture Using the Modified Lindholm Procedure

Objectives

Achilles tendon rupture (ATR) in adults often results from sporting activities, especially in young adults. There is no consensus in the literature on the best treatment approach in the treatment of these ruptures. The objective of this study was to evaluate the clinical long-term results of the augmented ATR repair using the modified Lindholm procedure (MLP).

Methods

Patients who underwent MLP due to ATR in the orthopedics and traumatology clinic of our hospital between 2007 and 2014 were retrospectively evaluated. Medical history of the patients was noted, and preoperative physical examination was routinely performed using the Thompson compression test. Patients’ demographic data such as age and gender, tendon rupture side, postoperative follow-up duration, and gap range values were recorded and evaluated.

Results

The mean age of the patients was 29.43 ± 7.10 years. The mean postoperative follow-up duration was 50.1 ± 8.20 months. Of the patients, 16 were injured during football, 10 during basketball, 2 during volleyball, and the remaining 8 during other sporting activities. When Arner-Lindholm scores were evaluated during follow-up, excellent outcome was achieved in 30 patients and good outcome was achieved in 6 patients, whereas there was no patient with poor outcome. None of the patients developed tendon re-rupture. At the end of the fourth postoperative month, the range of ankle motion was 100% in all patients.

Conclusions

In patients with spontaneous AT tendon rupture, MLP seems to prevent the re-rupture in the long-term period and should be considered as a safe procedure to repair ATR.

Achilles Tendon Reconstruction with Semitendinous Tendon Grafts Is Associated with a High Complication Rate

BACKGROUND

In the presence of a large gap where end-to-end repair of the torn Achilles tendon is difficult and V-Y advancement would likely be insufficient, augmentation is sometimes required. At our institute we have used primarily the hamstring autograft augmentation technique for the past two decades. The aim of this study was to analyze the complications after surgical treatment of Achilles tendon rupture with semitendinous tendon augmentation.

METHODS

We retrospectively analyzed 58 consecutive patients treated with semitendinous tendon autograft augmentation at the Helsinki University Hospital between January 1, 2006, and January 1, 2016.

RESULTS

During the study period, 58 patients were operated on by six different surgeons. Of 14 observed complications (24%), seven were major and seven were minor. Most of the complications were infections (n = 10 [71%]) The infections were noted within a mean of 62 days postoperatively (range, 22-180 days). Seven patients with a complication underwent repeated operation because of skin edge necrosis and deep infection (five patients), hematoma formation (one patient), and a repeated rupture (one patient).

CONCLUSIONS

In light of the experience we have had with autologous semitendinous tendon graft augmentation, we cannot recommend this technique, and, hence, we should abandon reconstruction of Achilles tendon ruptures with autologous semitendinous tendon grafts at our institute. Instead, other augmentation techniques, such as flexor hallucis longus tendon transfer, should be used.

Augmented Versus Nonaugmented Repair of Acute Achilles Tendon Rupture: A Systematic Review and Meta-analysis

BACKGROUND

Although simple end-to-end repair of the Achilles tendon is common, many augmented repair protocols have been implemented for acute Achilles tendon rupture. However, whether augmented repair is better than nonaugmented repair of an acute Achilles tendon rupture is still unknown.

PURPOSE

To conduct a meta-analysis to determine whether augmented surgical repair of an acute Achilles tendon rupture improved subjective patient satisfaction without an increase in rerupture rates. Secondary outcomes assessed included infections, ankle range of motion, calf muscle strength, and minor complications.

STUDY DESIGN

Meta-analysis.

METHODS

A systematic literature search of peer-reviewed articles was conducted to identify all randomized controlled trials (RCTs) comparing augmented repair and nonaugmented repair for acute Achilles tendon rupture from January 1980 to August 2016 in the electronic databases of PubMed, Web of Science (SCI-E/SSCI/A&HCI), and EMBASE. The keywords (Achilles tendon rupture) AND (surg* OR operat* OR repair* OR augment* OR non-augment* OR end-to-end OR sutur*) were combined, and results were limited to human RCTs and controlled clinical trials published in the English language. Four RCTs involving 169 participants were eligible for inclusion; 83 participants were treated with augmented repair and 86 were treated with nonaugmented repair.

RESULTS

Augmented repair led to similar responses when compared with nonaugmented repair for acute Achilles tendon rupture (93% vs 90%, respectively; P = .53). The rerupture rates showed no significant difference for augmented versus nonaugmented repair (7.2% vs 9.3%, respectively; P = .69). No differences in superficial and deep infections occurred in augmented (7 infections) and nonaugmented (8 infections) repair groups during postoperative follow-up ( P = .89). The average incisional infection rate was 8.4% with augmented repair and 9.3% with nonaugmented repair. No significant differences in other complications were found between augmented (7.2%) and nonaugmented (8.1%) repair ( P = .80).

CONCLUSION

Augmented repair, when compared with nonaugmented repair, was not found to improve patient satisfaction or reduce rerupture rate or infection rate. These conclusions are based on 4 trials with small sample sizes, and larger randomized trials are required to confirm these results.

Return to play post-Achilles tendon rupture: a systematic review and meta-analysis of rate and measures of return to play

AIM

This systematic review and meta-analysis sought to identify return to play (RTP) rates following Achilles tendon rupture and evaluate what measures are used to determine RTP.

DESIGN

A systematic review and meta-analysis were performed. Studies were assessed for risk of bias and grouped based on repeatability of their measure of RTP determination.

DATA SOURCES

PubMed, CINAHL, Web of Science and Scopus databases were searched to identify potentially relevant articles.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies reporting RTP/sport/sport activity in acute, closed Achilles tendon rupture were included.

RESULTS

108 studies encompassing 6506 patients were included for review. 85 studies included a measure for determining RTP. The rate of RTP in all studies was 80% (95% CI 75% to 85%). Studies with measures describing determination of RTP reported lower rates than studies without metrics described, with rates being significantly different between groups (p<0.001).

CONCLUSIONS

80 per cent of patients returned to play following Achilles tendon rupture; however, the RTP rates are dependent on the quality of the method used to measure RTP. To further understand RTP after Achilles tendon rupture, a standardised, reliable and valid method is required.

Augmented Compared with Nonaugmented Surgical Repair After Total Achilles Rupture: Results of a Prospective Randomized Trial with Thirteen or More Years of Follow-up

BACKGROUND

This prospective randomized trial with a mean fourteen-year follow-up compared simple end-to-end repair with fascial flap-augmented repair for acute Achilles tendon ruptures.

METHODS

From 1998 to 2001, sixty patients with acute Achilles tendon rupture were randomized to receive simple end-to-end repair or augmented repair; both groups were treated with postoperative bracing allowing free active plantar flexion. After a follow-up of thirteen years or more, fifty-five patients (twenty-eight in the nonaugmented-repair group and twenty-seven in the augmented-repair group) were reexamined. Outcome measures included the Leppilahti Achilles tendon score, isokinetic plantar flexion strength (peak torque and the work-displacement deficit at 10° intervals over the ankle range of motion), tendon elongation, and the RAND 36-item health survey.

RESULTS

After a mean of fourteen years of follow-up, the mean Leppilahti score was 87.1 points for the nonaugmented repairs and 91.5 points for the augmented repairs, with a mean difference of 4.3 points (95% confidence interval [CI], -0.1 to 8.8 points). The surgical technique did not have an impact on strength parameters, with a mean peak torque of 112.6 Nm after the nonaugmented repairs and 107.3 Nm after the augmented repairs (mean difference, 5.3 Nm [95% CI, -22.2 to 11.6 Nm]) and a median work-displacement deficit of 6.7% to 20.3% after the nonaugmented repairs and 12.8% to 18.0% after the augmented repairs (p = 0.9). Strength did not significantly change between the twelve-month and fourteen-year follow-up examinations. At a mean of fourteen years, the injured side showed a 12.2% to 18.0% median work-displacement deficit compared with the unaffected side (p < 0.001). RAND-36 scores indicated no between-group difference in health domains.

CONCLUSIONS

Augmented repair of total Achilles tendon ruptures provided no advantage over simple end-to-end repair. Achilles tendon ruptures result in a permanent calf muscle strength deficit, but its clinical relevance remains unclear.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Augmented Repair of Acute Achilles Tendon Rupture Using an Allograft Tendon Weaving Technique

Achilles tendon rupture is a common injury, especially in those who are physically active. Although open surgery is a widely used option for the treatment of acute Achilles tendon rupture, the optimal treatment is still disputed. In our study, 59 patients with unilateral, closed, acute rupture of the Achilles tendon were treated by open surgery using an allograft weave to augment the repair. All the surgeries were performed within 1 to 4 days after injury. The mean American Orthopaedic Foot and Ankle Society ankle-hindfoot score was recorded as 91.20 (range 88 to 95), 95.34 (range 92 to 98), and 98.27 (range 97 to 99) at the 3-, 6-, and 12-month follow-up visit, respectively. At the final follow-up visit, the mean difference between the mid-calf circumference of the injured and uninjured legs was 0.19 (range -0.03 to 1.50) cm (p = .43). At the final follow-up visit, the mean difference between the vertical distances from the plantar surface of the heel to the ground for the injured and uninjured lower extremities was 0.44 (range -0.03 to 0.5) cm (p = .17). Augmented repair using the allograft tendon weaving technique provided satisfactory tendon strength and functional outcomes and a timely return to the patients' activities.

Xenograft scaffold full-wrap reinforcement of Krackow achilles tendon repair

Standard 4-strand repair of Achilles tendon tears is effective, but additional strength may be desirable in patients who are compromised or those with reruptures. Use of a xenograft scaffold has not been investigated biomechanically in Achilles tendon repair. This study compared stiffness, gap formation, and ultimate load to failure with Krackow repair vs Krackow repair augmented with xenograft scaffold in 6 matched pairs of fresh-frozen human lower extremities. The Achilles tendon was transected 4 cm above the calcaneal insertion. Specimens were randomized to receive standard Krackow repair or Krackow repair augmented with a porcine xenograft scaffold. The graft was wrapped around the repaired tendon, sutured to itself with 2-0 FiberWire (Arthrex, Naples, Florida), and attached to the tendon distally and proximally and then medially and laterally. Specimens were loaded for 200 cycles between 5 and 30 N. Load to 5-mm gapping and load to ultimate failure were measured. Xenograft scaffold augmentation of standard Krakow Achilles tendon repair was significantly stronger and stiffer than standard Krackow repair in a biomechanical model immediately after repair (39.0±8.8 vs 24.4±4.6 N/mm; P=.01). The augmented repair group had significantly higher load to ultimate failure than did the Krackow group (862.7±174.0 vs 479.5±65.5 N; P<.01). Biological factors remain to be investigated, but this augmentation method could provide additional strength in patients who are compromised or those with reruptures.

Wound complications with posterior midline and posterior medial leg incisions: a systematic review

There is no consensus on the optimal incisional approach at the posterior leg to avoid wound healing complications. The purpose of this systematic review is to report and compare complication rates associated with two common incisions used to approach the Achilles tendon in order to provide additional recommendations for optimal incision placement.

MATERIALS AND METHODS

Four electronic databases were searched using keywords for procedures using posterior leg incisions. A total of 8724 studies were analyzed and subjected to inclusion and exclusion criteria. Once inclusion criteria were met, each article was placed in 1 of 2 groups based on incision placement: midline (group 1) or posterior medial (group 2). Study format, patient demographics, surgical indication and other details, and wound complications were recorded. The data obtained was reviewed for trends between the two groups.

RESULTS

38 articles met the inclusion criteria. Seven articles used the midline approach (group 1) whereas 31 articles used the posterior medial incision (group 2). The 38 articles included 1287 patients, of whom 25.6% were female with an average age of 43.9 years. Group 1 included 142 patients and group 2 had 1145 patients. The total wound complication rate among all reports was determined to be 8.2%, with 7.0% and 8.3% between groups 1 and 2, respectively.

DISCUSSION

Although incision placement may influence wound healing complications, it appears that additional factors such as advanced age, delay in surgical intervention, gender, comorbid conditions, prior surgery, and postoperative protocols also play a role. This report suggests that a midline approach is no less precarious in avoidance of wound complications regardless of patient demographics or other surgical details in comparison with a posterior medial incision.

LEVEL OF EVIDENCE

Therapeutic, Level IV.

Augmented repair of acute tendo Achilles ruptures with gastrosoleus turn down flap

BACKGROUND

We present the results of primary repair of acute tendo Achilles (TA) rupture augmented with gastrosoleus turn down flap technique.

PATIENTS AND METHODS

78 consecutive patients with a complete acute rupture of the Achilles tendon operated between 1993 and 2004 were included in study. We performed a modification of the Lindholm technique in which the primary Kessler suture repair of the tendon was augmented by a turn-down ~3 cm × 10 cm gastrosoleus aponeurosis flap. In all cases, a short-leg circular walking cast was applied at 90° of the ankle dorsiflexion for 3 weeks and all the patients were encouraged to full weightbearing ambulation immediately. After removal of the cast, isometric and isokinetic ankle exercises were performed for 3 weeks. Modified Rupp Score was used to evaluate the subjective satisfaction.

RESULTS

All of patients returned to daily activity and 54 (69%) of them returned to previous sport activity. The tendon repair failed in two patients and they were reoperated with an allograft. Three patients developed infection and one of them required débridement. One developed deep venous thrombosis and two permanent sural nerve injuries were encountered. One of the patients had a severe skin necrosis, which was treated with rotation flap. The mean Rupp score was 29 (3-33).

CONCLUSION

Primary repair of acute tendo Achilles rupture augment with gastrosoleus turn down flip technique in combination of immediate weightbearing ambulation provides a good outcome, but is associated with similar complication rates to the previous literature.

Complex Achilles reconstruction for massive soft tissue loss: allograft, autograft, and use of a temporary cement spacer

A 36-year-old male sustained loss of the Achilles mechanism secondary to a crush injury. The patient was treated with early placement of a cement spacer in the superficial posterior compartment, which allowed for successful late reconstruction.

Reconstruction of achilles tendon rupture with combined V-Y plasty and gastrocnemius-soleus fascia turndown graft

A reconstructive technique for treatment of Achilles tendon rupture with an extensive defect is presented. The primary goal of this salvage procedure is to create functional length and anatomic continuity among muscle, tendon, and bone. The procedure uses a combination of fascial advancement techniques: the V-Y advancement and the gastrocnemius-soleus fascia turndown graft. In this technique, the inverted "V" inscribed on the proximal gastrocnemius fascia is partially elevated from the underlying soleus and twisted 180 degrees on itself to augment the repair. Advancing the musculotendinous junction and creating a turndown graft provide substantial length. This combined technique allows the surgeon to repair ruptures with segmental defects greater than 10 cm in length.

Achilles tendon recurrent rupture following surgical repair: report on two cases

BACKGROUND

Rerupture is a main complication in Achilles tendon rupture surgery, with an incidence of 2-8%. Although wound break-down and rerupture are well known complications, spontaneous open rerupture has not been previously reported to the authors' knowledge.

METHODS

We report on two cases of open rerupture of Achilles tendon following augmented repair, through a transverse wound perpendicular to the primary incision line. Reruptures occurred 80 and 54 days after primary repair.

RESULTS AND CONCLUSIONS

After surgical repair long term follow-up results are good in both cases. This complication could be related to subtotal closure of the paratenon due to the bulk of the augmented repair and to an inadequate and a too extended period of postoperative ankle immobilization.

Optimizing Achilles tendon repair: effect of epitendinous suture augmentation on the strength of achilles tendon repairs

BACKGROUND

Epitendinous suture augmentation has been shown to increase gap resistance and overall strength in flexor tendon repairs of the hand. The purpose of this study was to evaluate the effect of various suture augmentation techniques in Achilles tendon repair.

MATERIALS AND METHODS

Eighteen fresh-frozen cadaveric Achilles tendons were transected and repaired with a 4-strand Krackow core stitch. Suture augmentation was performed with 3 figure-of-eight stitches in 6 specimens and a running cross-stitch weave in 6 specimens. The other 6 specimens were not augmented. Each tendon was loaded to failure on an MTS. Force to failure (defined as peak force or force at 5 mm gapping), gapping resistance, stiffness, and elongation were compared.

RESULTS

Force to failure (p < 0.001), stiffness (p < 0.01) and gapping resistance (p < 0.05) were increased by suture augmentation. Additionally failure force and gapping resistance for the cross-stitch augmentation was higher than the figure-of-eight augmentation (p < 0.05).

CONCLUSION

Cross-stitch augmentation of Achilles tendon repair yields a stronger and stiffer repair with greater resistance to gapping.

CLINICAL RELEVANCE

Achilles tendon repairs augmented with a cross stitch weave will be able to withstand substantially higher forces than non-augmented repairs.

Repair of experimental Achilles tenotomy with porcine renal capsule material in a rat model

Porcine small intestinal submucosa (SIS) is a collagenous acellular matrix which has found substantial utility as a tissue growth scaffold. In the present study, the utility of porcine renal capsule matrix (RCM) was compared to SIS in a rat Achilles tenotomy repair model. Groups of rats underwent surgical tenotomy followed by either no repair, repair with a SIS graft, or repair with a RCM graft. The weight-bearing ability of the manipulated limb was evaluated for 10 days following surgery using a subjective scale. Tenotomy sites sampled 28 days after surgery were numerically graded for degree of histologic change. There were no statistically significant differences between groups with respect to return to weight-bearing ability (p >or= 0.05) or degree of histologic change (p >or= 0.001); however, a non-significant trend suggested that rats treated with SIS or RCM experienced a faster return to limb function than untreated rats, and RCM-treated rats had slightly higher scores for degree of histologic change, suggesting a more rapid repair of the tenotomy site than in SIS-treated or untreated rats. The harvested tenotomy sites in all treatment groups were characterized by marked fibroplasia and presence of macrophages. Remnants of SIS surrounded by macrophages and multi-nucleated giant cells were still present in some rats, however remnants of RCM were not observed, suggesting more rapid incorporation of RCM. The results show that RCM is equivalent to SIS as a material for repair of Achilles tendon injury and merits further study in other tendon injury models.