Effect of Suture Caliber and Number of Core Strands on Repair of Acute Achilles Ruptures: A Biomechanical Study

Progression of partial to complete ruptures of the Achilles tendon during rehabilitation: A study using a finite element model

Substantial research on complete Achilles tendon ruptures is available, but guidance on partial ruptures is comparatively sparse. Conservative management is considered acceptable in partial tendon ruptures affecting less than 50% of the tendon's width, but supporting experimental evidence is currently lacking. Using a previously validated finite element model of the Achilles tendon, this study aimed to assess whether loading conditions simulating an early functional rehabilitation protocol could elicit progression to a complete rupture in partial ruptures of varying severity. In silico tendon rupture simulations were performed to locate the most likely rupture site for least, moderate, and extreme subtendon twist configurations. These three models were split at the corresponding rupture site and two sets of partial ruptures were created for each, starting from the medial and lateral sides, and ranging from 10% to 50% loss of continuity. Simulations were conducted with material parameters from healthy and tendinopathic tendons. Partial ruptures were considered to progress if the volume of elements showing a maximum principal strain above 10% exceeded 3 mm3. To assess whether the tendinopathic tendons typical geometric characteristics could compensate for the inferior material properties found in tendinopathy, an additional model with increased cross-sectional area in the free tendon region was developed. Progression to complete ruptures occurred even with less than a 50% loss of continuity, regardless of subtendon twisting, and material parameters. The tendinopathic tendon model with increased cross-sectional area showed similar results. These findings suggest the current criteria for surgical treatment of partial ruptures should be reconsidered. Statement of clinical significance: The clinical significance and most appropriate treatment of partial ruptures of the Achilles tendon is unclear. Despite the widespread use of the "50% rule" in treatment decisions of partial tendon ruptures, experimental evidence supporting it is missing. The present study provides new data, from a validated aponeurotic and free Achilles tendon finite element model, showing that partial ruptures may progress to complete ruptures under loading conditions elicited from functional rehabilitation protocols, even for partial ruptures affecting less than 50% of the tendon's width. Under these novel findings, the current criteria for surgical treatment of partial ruptures should be reconsidered.

Achilles Tendon Rupture

There are many high-level studies comparing nonoperative treatment, open repair, and minimally invasive repair for Achilles tendon ruptures. This article summarizes the most up-to-date literature comparing these treatment options. The authors' preferred protocol for nonoperative treatment is discussed. Preferred techniques for open repair and chronic Achilles repair are discussed with reference to the literature.

Gouty Tophi Encompassing Retained Suture Material 7 Years After Achilles Tendon Rupture Repair

CASE

We report the case of a 32-year-old male patient with no history of gout who developed gouty tophi encompassing retained suture material 7 years after initial repair of a ruptured Achilles tendon. The patient had a posterior ankle mass concerning for abscess. Monosodium urate crystals were identified, and uric acid level was elevated at the time of irrigation and debridement.

CONCLUSION

Surgical site gout is a rare but important phenomenon to recognize in the treatment of patients with Achilles tendon repairs, particularly in patients with a history of abscess, infection, or collections localized to retained suture material.

Achilles Tendon Ruptures and Repair in Athletes-a Review of Sports-Related Achilles Injuries and Return to Play

PURPOSE OF REVIEW

Achilles tendon ruptures (ATR) are detrimental to sports performance, and optimal treatment strategy and guidelines on return to play (RTP) remain controversial. This current review investigates the recent literature surrounding nonoperative versus operative management of ATR, clinical outcomes, and operative techniques to allow the athlete a successful return to their respective sport.

RECENT FINDINGS

The Achilles tendon (AT) is crucial to the athlete, as it is essential for explosive activities such as running and jumping. Athletes that sustain an ATR play in fewer games and perform at a lower level of play compared to age-matched controls. Recent studies also theorize that ATRs occur due to elongation of the tendon with fatigue failure. Biomechanical studies have focused on comparing modes of fixation under dynamic loading to recreate this mechanism. ATRs can be career-ending injuries. Fortunately, the recent incorporation of early weight-bearing and functional rehabilitation programming for non-operative and operative patients alike proves to be beneficial. Especially for those treated nonoperatively, with the incorporation of functional rehabilitation, the risk of re-rupture among non-operative patients is beginning to approach the historical lower risk of re-rupture observed among patients treated operatively. Despite this progress in decreasing risk of re-rupture particularly among non-operative patients, operative managements are associated with unique benefits that may be of particular interest for athletes and active individuals. Recent studies demonstrate that operative intervention improves strength and functional outcomes with more efficacy compared to nonoperative management with rehabilitation. The current literature supports operative intervention in elite athletes to improve performance and shorten the duration to RTP. However, we acknowledge that surgical intervention does have inherent risks. Ultimately, most if not all young and/or high-level athletes with an ATR benefit from surgical repair, but it is crucial to take a stepwise algorithmic approach and consider other factors, which may lead towards nonoperative intervention. These factors include age, chronicity of injury, gap of ATR, social factors, and medical history amongst others in this review.

Biomechanical Comparison of Tape Versus Suture in Simulated Achilles Tendon Midsubstance Rupture

As sutures have progressed in strength, increasing evidence supports the suture tendon interface as the site where most tendon repairs fail. We hypothesized that suture tape would have a higher load to failure versus polyblend suture due to its larger surface area. Eleven matched pairs of cadaveric Achilles tendons were sutured with 2 mm wide braided ultrahigh molecular weight polyethylene tape (Tape) or 2 mm wide braided ultrahigh molecular weight polyethylene suture (Suture) using a Krackow repair method. All Achilles repair constructs were cyclically loaded, after which they were loaded to failure. Change in suture footprint height, clinical and ultimate load to failure, and location of failure was recorded. Clinical loads to failure for Tape and Suture were 290.4 ± 74.8 and 231.7 ± 70.4 Newtons, respectively (p= .01). Ultimate loads to failure for Tape and Suture were 352.9 ± 108.1 and 289.8 ± 53.7 Newtons, respectively (p = .11). Cyclic testing resulted in significant changes in footprint height for both Tape and Suture, but the 2 sutures did not differ in terms of the magnitude of change in footprint height (p = .52). The suture tendon interface was the most common site of failure for both Tape and Suture. Our results suggest that Tape may provide added repair strength in vivo for Achilles midsubstance rupture.

Acute Achilles Tendon Ruptures

There is an ever-evolving debate about the best treatment option for Achilles tendon ruptures. There was a relative consensus that operative treatment yielded the best outcomes. Much of this is based on results in athletic populations. Conservative treatment was considered only for the elderly and those with very inactive lifestyles. There has been an evolution, however, with more surgeons utilizing an aggressive functional rehabilitation with conservative management. Surgical intervention still is the treatment of choice for elite-level athletes. The treatment of choice for patient populations other than elite athletes remains an individual choice between patient and physician.

Clinical Outcomes and Complications Following Limited Open Achilles Repair Without an Instrumented Guide

BACKGROUND

We report the clinical outcomes and complications following our limited open incision Achilles tendon repair technique without instrument guides.

METHODS

A total of 33 patients were included in this study. We recorded pre- and postoperative scores on the Foot and Ankle Disability Index (FADI), visual analog scale (VAS), and the Foot and Ankle Outcome Score (FAOS). Subgroup analyses were performed for acute (<2 weeks) and subacute (2-6 weeks) Achilles tendon repairs. A P value <.05 was considered significant for all statistical analyses.

RESULTS

The median time from injury to surgery was 10.0 days (range, 1-45 days). At a median follow-up of 3.7 years (range, 1.0-9.8 years), the average pre- and postoperative outcome scores improved significantly for the following: FADI index (49.1-98.4, P < .001), VAS (4.8-0.2, P < .001), FAOS Pain (54.8-99.2, P < .001), FAOS Symptoms (84.6-97.0, P < .001), FAOS activities of daily living (61.4-97.2, P < .001), FAOS Sports and Recreational Activity (39.5-98.5, P < .001), and FAOS quality of life (39.7-88.7, P < .001). There were no significant differences between pre- and postoperative outcome scores between the acute and subacute Achilles repair groups. There were no wound complication, reruptures, or reoperations in the entire cohort.

CONCLUSION

Patients showed improvements in postoperative patient-reported outcome scores with minimal complications. There was no significant difference in outcomes for acute vs subacute repairs. Our limited open incision Achilles tendon repair, which required no additional targeting instrumentation, had favorable midterm results.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Comparison of the double loop knot stitch and Kessler stitch for Achilles tendon repair: A biomechanical cadaver study

Tendon elongation after Achilles tendon (AT) repair is associated with the clinical outcome. Reliable suture techniques are essential to reduce gap formations and to allow early mobilization. Cyclic loading conditions represent the repetitive loading in rehabilitation. The aim of this study was to compare the Kessler stitch and double loop knot stitch (DLKS) in a cyclic loading program focussing on gap formation. Sixteen human cadaveric ATs were transected and sutured using either the Kessler stitch or DLKS (eight matched pairs). The suture-tendon configurations were subjected to cyclic loading and additional ultimate load to failure testing using the Zwick 1446 universal testing machine. Each AT survived cyclic loading, with a mean gap formation less than 5 mm after 1000 cycles. The mechanical properties of the Kessler stitch and DLKS were not significantly different after cyclic loading with a mean displacement of 4.57 mm (± 1.16) for the Kessler stitch and 4.85 mm (± 1.14) for the DLKS (P = .76). There were no significant differences in the ultimate load testing (P = .85). Both bioprotective techniques prevent excessive gaping in cyclic testing when tendon loading is moderate. Our data and those from literature of gap formation in cyclic and ultimate loading allow the conclusion, that early aggressive AT loading after repair (e.g. full weightbearing) overstrain simple as well as complex suture configurations. Initial intraoperative tightening of the knots (preloading) before locking is important to decrease postoperative elongation.

MRI Assessment of Degeneration of the Tendon in Achilles Tendon Ruptures

BACKGROUND

The extent of tendinosis along the entire tendon in Achilles tendon ruptures (ATRs) has not previously been assessed. MR images of acute ATRs were evaluated to assess this extent, even in areas distant from the rupture.

METHODS

Patients who had MR images for an ATR were reviewed. Each tendon was divided into a proximal, middle, and distal segment with the full tendon length defined as the length measured from the myotendinous junction to the insertion. The site of tendon rupture, presence of tendinosis and/or additional tearing, and largest anteroposterior (AP) diameter in the remaining segments were noted. In total, 45 MR iamges were included in our study.

RESULTS

The mean total tendon length was 9.93 cm, while the length from the insertion to the tear was 5.86 cm. Of the 45 ruptures, 20 (44.4%) were in the proximal third, 19 (42.2%) in the middle third, and 6 (13.3%) in the distal third. In all remaining segments where no ruptured tendon was observed, tendinosis was seen. Further, of the 90 segments of a tendon without rupture, 87 (96.7%) had an AP diameter greater than 6 mm. Of those 90 segments without rupture, 24 (26.7%) had a secondary partial-thickness tear in another third.

CONCLUSION

Tendinosis is a known precursor of an ATR that in the current study was not limited to the area of rupture. The finding of extensive tendon degeneration may have implications for the optimal surgical treatment.

LEVEL OF EVIDENCE

Level IV, case series.

A Percutaneous Knotless Technique for Acute Achilles Tendon Ruptures

Achilles tendon ruptures are a common tendon injury, usually occurring in middle-aged men during recreational sporting activities. Both nonoperative and operative management are employed to treat these injuries. Several operative treatments are described in the literature, including percutaneous Achilles repair, mini-open repair, and open repair. Open Achilles repair is associated with higher rates of impaired wound healing and infection, whereas minimally invasive techniques have been reported to have an increased risk of iatrogenic sural nerve injury. More recently, low complication rates, improved cosmetic appearance, reduced operating times, and improved clinical outcomes have been reported for the percutaneous Achilles repair technique. In this Technical Note, we present our preferred technique using the Percutaneous Achilles Repair System (Arthrex, Naples, FL), which has been reported to have minimal wound and nerve complications, and early return to activity.

Tendon end separation with loading in an Achilles tendon repair model: comparison of non-absorbable vs. absorbable sutures

Background

Rupture of the Achilles tendon often leads to long-term morbidity, particularly calf weakness associated with tendon elongation. Operative repair of Achilles tendon ruptures leads to reduced tendon elongation. Tendon lengthening is a key problem in the restoration of function following Achilles tendon rupture. A study was performed to determine differences in initial separation, strength and failure characteristics of differing sutures and numbers of core strands in a percutaneous Achilles tendon repair model in response to initial loading.

Methods

Nineteen bovine Achilles tendons were repaired using a percutaneous/minimally invasive technique with a combination of a modified Bunnell suture proximally and a Kessler suture distally, using non-absorbable 4-strand 6-strand repairs and absorbable 8-strand sutures. Specimens were then cyclically loaded using phases of 10 cycles of 100 N, 100 cycles of 100 N, 100 cycles of 190 N consistent with early range of motion training and weight-bearing, before being loaded to failure.

Results

Pre-conditioning of 10 cycles of 100 N resulted in separations of 4 mm for 6-strand, 5.9 mm for 4-strand, but 11.5 mm in 8-strand repairs, this comprised 48.5, 68.6 and 72.7% of the separation that occurred after 100 cycles of 100 N. The tendon separation after the third phase of 100 cycles of 190 N was 17.4 mm for 4-strand repairs, 16.6 mm for 6-strand repairs and 26.6 mm for 8-strand repairs. There were significant differences between the groups (p < 0.0001). Four and six strand non-absorbable repairs had significantly less separation than 8-strand absorbable repairs (p = 0.017 and p = 0.04 respectively).

The mean (SEM) ultimate tensile strengths were 4-strand 464.8 N (27.4), 6-strand 543.5 N (49.6) and 8-strand 422.1 N (80.5). Regression analysis reveals no significant difference between the overall strength of the 3 repair models (p = 0.32) (4 vs. 6: p = 0.30, 4 vs. 8: p = 0.87; 6 vs. 8: p = 0.39). The most common mode of failure was pull out of the Kessler suture from the distal stump in 41.7% of specimens.

Conclusion

The use of a non-absorbable suture resulted in less end-to-end separation when compared to absorbable sutures when an Achilles tendon repair model was subject to cyclical loading. Ultimate failure occurred more commonly at the distal Kessler suture end although this occurred with separations in excess of clinical failure. The effect of early movement and loading on the Achilles tendon is not fully understood and requires more research.