Tendon Augmentation Research Articles

Delivered growth factor therapy to improve healing after rotator cuff repair

BackgroundDegenerative rotator cuff tears are a significant cause of shoulder pain in the aging population. Rotator cuff repair surgery may be more successful when growth factors are delivered to the repair site. This study was designed to determine the cellular processes involved in normal bone-to-tendon healing and the current approaches used for biologic augmentation of rotator cuff repair.MethodsThis review focuses on animal studies of rotator cuff repair and early human trials.ResultsRegular bone-to-tendon healing forms a fibrous junction between tendon and bone that is markedly different from the original bone-to-tendon junction. Tendon augmentation with cellular components serves as scaffolding for endogenous fibroblastic cells and a possible source of growth factors and fibroblastic cells. Extracellular matrices provide a scaffold for incoming fibroblastic cells. However, research in extracellular matrices is not conclusive due to intermanufacturer variation and the lack of human subject research. Growth factors and platelet-rich plasma are established in other fields of research and show promise, but have not yet been rigorously tested in rotator cuff repair augmentation.ConclusionsRotator cuff repair can benefit from biologic augmentation. However, research in this field is still young and has not yet demonstrated that the benefits in healing rates are significant enough to merit regular clinical use. Randomized controlled trials will elucidate the use of biologic augmentation in rotator cuff repairs.

Tissue engineered biological augmentation for tendon healing: a systematic review

Tendon injuries give rise to significant morbidity. In the last few decades, several techniques have been increasingly used to optimize tendon healing. We performed a comprehensive search of PubMed, Medline, Cochrane, CINAHL and Embase databases using various combinations of the commercial names of each scaffold and the keywords 'tendon', 'rotator cuff', 'supraspinatus tendon', 'Achilles tendon', 'growth factors', 'cytokines', 'gene therapy', 'tissue engineering', 'mesenchymal' and 'stem cells' over the years 1966-2009. All articles relevant to the subject were retrieved, and their bibliographies were hand searched for further references in the context to tissue-engineered biological augmentation for tendon healing. Several new techniques are available for tissue-engineered biological augmentation for tendon healing, growth factors, gene therapy and mesenchimal stem cells. Data are lacking to allow definitive conclusions on the use of these techniques for routine management of tendon ailments. The emerging field of tissue engineering holds the promise to use new techniques for tendon augmentation and repair. Preliminary studies support the idea that these techniques can provide an alternative for tendon augmentation with great therapeutic potential. The optimization strategies discussed in this article are currently at an early stage of development. Although these emerging technologies may develop into substantial clinical treatment options, their full impact needs to be critically evaluated in a scientific fashion.

Repair of Insertional Achilles Tendinosis With a Bone-Quadriceps Tendon Graft

While conservative treatment may be successful in most cases, partial rupture at the calcaneal insertion point is a significant concern with insertional Achilles tendinopathy. We report on the outcomes of a surgical technique for Achilles tendon augmentation using a bone-tendon graft harvested from the knee extensor system. Our retrospective case series includes 25 surgical procedures performed in 24 patients, 19 males and five females, with a mean age of 47 (range, 30 to 59) years, 18 of whom were athletes. The mean followup period was 52 (range, 12 to 156) months. All patients underwent MRI examination prior to surgery which showed partial Achilles tendon rupture. The Achilles tendon was debrided through a posterolateral approach. The bone-quadriceps tendon graft was harvested, then the bone plug of the graft was inserted into a blind tunnel drilled into the calcaneus and fixed with an interference screw. The fibers of the quadriceps tendon were sutured to the residual part of the Achilles tendon with the foot at an angle of 90 degrees. Patients were able to resume their sporting activity after an average of 6.7 months. At last followup examination, physical activity was scored 5.2 on the 10-point Tegner Scale; the mean AOFAS score was 98.4. MRI examination showed good graft integration 1 year postoperatively. The bone-quadriceps tendon grafting technique was a good alternative for the insertional Achilles lesions with partial detachment which we felt required augmentation.

Endosopic Achilles tendon augmentation with a graft loop anatomic and radiologic study

Mini-invasive techniques are commonly used for repair of tendon Achilles (TA) rupture. However, the use of these techniques is limited when graft augmentation is needed. A radiological study was conducted on 18 normal ankles using multi-slice CT scan with soft tissue reconstruction to determine the endoscopic landmarks for Achilles tendon insertion. The surgical procedure was performed on six whole lower limb formaldehyde preserved specimens. Endoscopic-assisted TA augmentation with a graft loop was done for all specimens. Postoperative assessment of the tunnel was done using multi-slice CT scan. Anatomic dissection showed that the sural nerve and neurovascular bundle were intact in all specimens. With the technique described a graft loop can be delivered endoscopically for Achilles tendon augmentation. The technique was found to be safe for the sural nerve and medial neurovascular structures.

Strategies in Biologic Augmentation of Rotator Cuff Repair: A Review

Degenerative rotator cuff tears are increasing with the aging population, and healing is not uniform after surgery. Rotator cuffs may show improved healing when biologic factors are added during surgery. We asked: (1) What cellular processes are involved in normal bone-to-tendon healing? (2) What approaches are being developed in tendon augmentation? (3) What approaches are being developed with the addition of growth factors? We reviewed research in relating to biologic augmentation and cellular processes involved in rotator cuff repair, focusing on animal models of rotator cuff repair and nonrandomized human trials. Regular bone-to-tendon healing forms a fibrous junction between tendon and bone that is distinct from the original bone-to-tendon junction. Tendon augmentation with cellular components serves as scaffolding for fibroblastic cells and a possible source of growth factors and fibroblastic cells. Extracellular matrices provide a scaffold for incoming fibroblastic cells, although current research does not conclusively confirm which if any of these scaffolds enhance repair owing in part to intermanufacturer variations and the limited human research. Growth factors and platelet-rich-plasma are established in other fields of research and may enhance repair but have not been rigorously tested. There is potential application of biologic augmentation to improve healing after rotator cuff repair. However, research in this field is still inconclusive and has not been sufficiently demonstrated to merit regular clinical use. Future human trials can elucidate the use of biologic augmentation in rotator cuff repairs.

Patellar tendon repair with hamstring autograft: A cadaveric analysis

Background Rupture of the patellar tendon requires surgical repair to restore function of the knee. The most accepted repair technique utilizes running locking non-absorbable sutures secured to the patella through three drill holes. Complications with this repair technique include rerupture, knee stiffness, and extensor lag caused by gap formation at the site of repair. Some surgeons have suggested augmenting the standard repair with local autograft tendon to avoid these complications. It was hypothesized that using a repair technique that included augmentation of the repair with autograft tendons would decrease the gap formation at the repair site under cyclic loading conditions. Methods In this experiment, eight specimens were used to analyze two methods of patellar tendon repair: hamstrings autograft augmentation and a standard repair using three vertical bone tunnels in the patella. Each specimen was then extended with a 2.2 kg weight on the tibia at 0.25 Hz to simulate early motion after surgery. The gap formed at the repair site was then measured at 1, 10, 100, and 250 cycles and both techniques confidence interval compared using a Wilcoxon signed rank test. Findings The mean gap formation for the standard repair after one cycle was 8.9 mm (SD 2.4) and for the augmented repair was 3.6 mm (SD 0.9). At 250 cycles the mean gap formed for the standard repair was 13.2 mm (SD 1.9) and the mean gap for the augmented repair was 7.2 mm (SD 0.9). All gaps for all cycles analyzed had an 88% confidence interval for significance using a Wilcoxon signed rank test. Interpretation The biomechanical results of this study show statistical trend toward decrease gap formation with an augmented tendon at the repair site under a simulated dynamic knee motion.

Tendon augmentation grafts: a systematic review

Several biomaterials are available to bridge large tendon defects or reinforce tenuous tendon repairs. We performed a comprehensive search of PubMed, Medline, Cochrane, CINAHL, and Embase databases using various combinations of the commercial names of each scaffold and the keywords 'tendon', 'rotator cuff', 'supraspinatus tendon', 'Achilles tendon', 'scaffold', 'biomaterials', 'extracellular matrix', 'substitute', and 'devices' over the years 1966-2009. All articles relevant to the subject were retrieved, and their bibliographies hand searched for further references in the context to biomaterials for tendon repair. Many biomaterials are available for tendon augmentation. Scanty evidence is available for the use of these scaffolds. The emerging field of tissue engineering holds the promise to use biomaterials for tendon augmentation. Preliminary studies support the idea that these biomaterials have the ability to provide an alternative for tendon augmentation. However, available data are lacking to allow definitive conclusion on the use of biomaterials for tendon augmentation. Additionally, the prevalence of postoperative complications encountered with their use varies within the different studies. Rather than providing strong evidence for or against the use of these materials for tendon augmentation, this study instead generates potential areas for additional prospective investigation.

Augmentation of Tendon–Bone Interface Healing With Low-intensity Pulsed Ultrasound

Augmentation of Tendon–Bone Interface Healing With Low-intensity Pulsed Ultrasound

Special Segment: Soft Tissue Matrices—One Form of Acellular Human Dermis for Use in Tendon and Ligament Repairs in the Foot and Ankle

Trauma to tendons and ligaments represents a significant part of orthopaedic and podiatric injuries. To improve the outcome of repair, complex or chronic injuries may require reinforcement of the primary repair with a graft. Biologic grafts currently available provide different handling, strength, and biological responses. One of the currently available grafts, an acellular human dermal membrane with specific properties, has been successfully used in the augmentation of tendon and ligament repairs for more than 6 years.

Two Hypothetical Nystagmus Procedures: Augmented Tenotomy and Reattachment and Augmented Tendon Suture ( Sans Tenotomy)

To review the hypothetical mechanism and therapeutic benefits of the four-muscle tenotomy and reattachment (T&R) procedure using knowledge accrued over the 10 years since its proposal; to describe an augmented tendon suture (ATS) technique to improve the procedure based on one of the originally suggested alternative methods (mechanical); and to hypothesize a new ATS procedure to achieve the same therapeutic benefits without extraocular muscle tenotomy or reattachment to the globe. Standard surgical methods were used. The T&R procedure damps and improves infantile nystagmus syndrome (INS) waveforms, improves eXtended Nystagmus Acuity Function (NAFX) values, broadens the NAFX peak versus gaze angle, and damps slow eye movements but not saccades. The T&R procedure also damps acquired pendular and downbeat nystagmus, decreasing the patients' oscillopsia, and lowers the target acquisition time in INS. The T&R procedure directly affects only the enthesis of the tendon; there is idiosyncratic variation in the distribution of afferent fibers in the tendons. The ATS technique consists of placing several additional sutures in the tendon proximal to the tenotomy. Based on the hypothetical proprioceptive mechanism for the beneficial effects of the T&R procedure, the authors hypothesize that the ATS technique will maximize the therapeutic benefits and that an ATS procedure, using only tendon sutures without tenotomy, will duplicate the therapeutic effects of T&R. Eliminating the tenotomy component results in a simpler procedure more suitable for single-session, multi-muscle surgery that may be required for improving the waveforms of multiplanar nystagmus and less prone to cause complications.

Two Hypothetical Nystagmus Procedures: Augmented Tenotomy and Reattachment and Augmented Tendon Suture (SansTenotomy)

Two Hypothetical Nystagmus Procedures: Augmented Tenotomy and Reattachment and Augmented Tendon Suture (<i>Sans</i>Tenotomy)

Arthroscopic augmentation technique with 4-strand semitendinosus tendon for partial tears of the anterior cruciate ligament

Objective To introduce an augmentation technique with 4-strand semitendinesus ten-don in treatment of partial anterior cruciate ligament (ACL) injury of under arthroscope and investigate the clinical outcome of the technique. Methods A total of 26 patients with posterolateral bundle rup-tures of ACL were treated arthroscopically with 4-strand semitendinosus tendon augmentation. The Inter-nationnal Knee Documentation Committee (IKDC) and Lysholm knee score scale were used for evaluation of knee function. The side-to-side difference in anterior knee laxity was examined by KT-1000 (25 de-grees flexion and 301b). Results There was no knee extension limitation, with knee flexion of 130°-150 °(average 142°). The patients were followed up for 12-18 months, which showed grade A in 25 pa-tients (96%) and grade B in one (4%) according to IKDC grade at final follow-up. The subjective IK-DC score was increased from preoperative (71.4±3.7) points to (95.8±3.4) points at final follow-up (t =9.836,P <0.01). The average side-to-side difference in maximal manual test with KT-1000 ar-thrometer at 25° flexion decreased from preoperative (5.1±1.2) mm to (2.1±1.3)mm at final follow-up (t = 10.48 ,P < 0.01). The Lysholm score of all patients was (76.7±3.2) preoperatively and (95. 7±2.4) at final follow-up (t =7.356,P<0.01). Conclusion Augmentation with 4-strand semiten-dinosus tendon under arthroscope can attain excellent clinical results and good anterior stability in treat-ment of partial tears of posterolateral bundle of ACL. Key words: Arthroscopy; Anterior cruciate ligament; Reconstruction

Augmentation of Tendon–Bone Interface Healing With Low-intensity Pulsed Ultrasound

The capacity of low-intensity pulsed ultrasound to accelerate the integration of grafted tendon-within-bone tunnel was evaluated. The extensor digitorum longus tendons of 20 New Zealand white rabbits were transplanted into bone tunnels in both proximal tibias. One side was chosen randomly to receive low-intensity pulsed ultrasound. The other side served as control. Six rabbits each were sacrificed at 2 and 3 weeks postoperatively for biomechanical testing, and 2 rabbits each were sacrificed at 1, 3, 6, and 12 weeks postoperatively for histological study. At 2 weeks postoperatively, the mean maximal tensile strength in the ultrasound-treated group (30.676 N) was significantly stronger (P<.05) than the control group (17.924 N). There was no significant difference of the maximal tensile strength (33.674 vs 33.340 N; P=.753) between the ultrasound-treated and control groups at 3 weeks postoperatively. In the ultrasound-treated group, the histological study revealed the interface filled with denser granulation tissue and diffuse perpendicular anchored fibers in the 1- and 3-week specimens, and interface new bone formation in the 6- and 12-week specimens. The biomechanical and histological studies demonstrated that the low-intensity pulsed ultrasound enhanced the healing of grafted tendon-to-bone tunnel in the early stages. Our findings indicate that low-intensity pulsed ultrasound is a potentially promising mechanical tool to accelerate early tendon healing to bone tunnel.

Cyclic Loading of 3 Achilles Tendon Repairs Simulating Early Postoperative Forces

Background Accelerated rehabilitation has been advocated after Achilles tendon repair, but it produces significant forces at the repair site. Hypothesis Stresses applied to the repaired Achilles tendon simulating postoperative forces may exceed the strength of some repairs. Study Design Controlled laboratory study. Methods Fifteen Achilles tendons were incised 4 cm proximal to the calcaneal insertion, then were repaired using either a percutaneous, 4-strand Krackow, or an epitendinous augmented 4-strand Krackow technique. Tendons were cyclically loaded to 1000 cycles each at 100, 190, and 369 N. The number of cycles to initial gapping, 5-mm gapping, and total failure were compared using Mann-Whitney U tests with adjustments for multiple comparisons. Results Gap resistance was significantly greater for augmented Krackow repairs (2208 cycles to initial gapping) versus nonaugmented repairs (502 cycles, P = .024) and for nonaugmented Krackow repairs versus percutaneous repairs (5 cycles, P = .024). All percutaneous repairs failed during the 100-N cycling (102 ± 135 cycles). All nonaugmented Krackow repairs failed during the 190-N cycles (total cycles to failure: 1268 ± 345). All augmented Krackow repairs were intact (no gapping) after the 190-N cycles. Four failed during 369-N cycling (total cycles to failure, 2017 ± 11), and 1 remained intact for 3000 cycles. Conclusion Epitendinous cross-stitch weave augmentation of Achilles tendon repairs significantly increased repair strength and gap resistance. Clinical Relevance Epitendinous cross-stitch weave augmentation of Achilles tendon repairs may better allow for early stretching and ambulation after Achilles tendon repair.

Ipsilateral free semitendinosus tendon graft transfer for reconstruction of chronic tears of the Achilles tendon

BackgroundMany techniques have been developed for the reconstruction of the Achilles tendon in chronic tears. In presence of a large gap (greater than 6 centimetres), tendon augmentation is required.MethodsWe present our method of minimally invasive semitendinosus reconstruction for the Achilles tendon using one para-midline and one midline incision.ResultsThe first incision is a 5 cm longitudinal incision, made 2 cm proximal and just medial to the palpable end of the residual tendon. The second incision is 3 cm long and is also longitudinal but is 2 cm distal and in the midline to the distal end of the tendon rupture. The distal and proximal Achilles tendon stumps are mobilised. After trying to reduce the gap of the ruptured Achilles tendon, if the gap produced is greater than 6 cm despite maximal plantar flexion of the ankle and traction on the Achilles tendon stumps, the ipsilateral semitendinosus tendon is harvested. The semitendinosus tendon is passed through small incisions in the substance of the proximal stump of the Achilles tendon, and it is sutured to the Achilles tendon. It is then passed beneath the intact skin bridge into the distal incision, and passed from medial to lateral through a transverse tenotomy in the distal stump. With the ankle in maximal plantar flexion, the semitendinosus tendon is sutured to the Achilles tendon at each entry and exit pointConclusionThis minimally invasive technique allows reconstruction of the Achilles tendon using the tendon of semitendinosus preserving skin integrity over the site most prone to wound breakdown, and can be especially used to reconstruct the Achilles tendon in the presence of large gap (greater than 6 centimetres).

Chondrolysis after partial lateral meniscectomy in athletes

Rapid chondrolysis after partial arthroscopic lateral meniscectomy has been seldom reported in literature. Considering the relatively high number of partial lateral meniscectomy performed, we cannot understand why this complication is so rare. The purpose of this paper is to report a series of athletes developing a chondrolysis associated with posterolateral corner laxity after a partial lateral meniscectomy and attempt to hypothesize the pathogenesis of this devastating complication. Five male professional soccer players of Italian championship with a mean age of 26.8 years underwent a partial lateral meniscectomy because of a traumatic lateral meniscus tear. Patients showed a slight varus knee and there were clinical signs compatible with a meniscal tear. No other pathological sign were found. An MRI scan confirmed these findings. After surgery patients were unable to resume sport activities because of swelling and knee pain during training sessions. At a mean time of 8 months (range 6-12 months) from surgery patients were re-examined and a new MRI scan was performed. Clinical examination revealed a slight swelling of the knee and signs of posterolateral corner laxity. MRI scan revealed intra-articular fluid and pathological findings of knee posterolateral corner associated with a thinning of the articular cartilage. Arthroscopy showed free cartilagineous debris floating into the knee and a high grade of cartilage damage on the lateral compartment. The evaluation of lateral compartment, ruled-out a new tear of the meniscal remnant and showed a positive drive-trough sign with knee in the Fig. 4 positioning. All patients had an open re-tensioning of the posterior meniscofemoral capsule, and in one case, an augmentation of the popliteal tendon using a free semi-tendinous graft was also done. This surgery gave a complete resolution of symptoms and patients resumed sports activities without any restriction after a period between 4 and 5 months. Based on this experience we hypothesize that partial lateral meniscectomy may have a role in causing a subtle rotatory instability that combined with high stress of sports activity can dramatically increase the susceptibility of joint to chondrolysis, Varus knee seems to be a possible predisposing factor. Open surgery addressing the insufficiency of lateral or posterolateral corner has been found to be effective in improving knee function and resolve patients symptoms at a short-term follow-up.

An assessment of porcine dermal xenograft as an augmentation graft in the treatment of extensive rotator cuff tears

Porcine dermal collagen (Zimmer Patch, formerly known as Permacol; Tissue Science Laboratories plc, Aldershot, Hampshire, UK) has been used for reinforcement of several human body tissues with success and has been shown to act as a durable, permanent tissue scaffold that assists healing. The purpose of this study was to determine the effectiveness of porcine dermal collagen as a tendon augmentation graft in the repair of extensive rotator cuff tears. This prospective study evaluated the clinical, ultrasound, and magnetic resonance imaging outcome 4.5 years (range, 3-5 years) after the treatment of extensive rotator cuff tears with porcine dermal collagen tendon augmentation grafting. The study group consisted of 10 patients (5 men, 5 women) with a mean age of 66 years (range, 46-80 years). Patients were evaluated clinically using the Constant score preoperatively, at 1 year, and at final follow-up when ultrasound and magnetic resonance imaging scans were performed to assess for graft and rotator cuff integrity. Average Constant scores improved from 41 preoperatively to 62 at final follow-up (P = .0003). Pain, abduction power, and range of motion significantly improved after surgery (P < .05), and patient satisfaction levels were high. Imaging studies identified intact grafts in 8 patients and graft detachment in 2. No adverse side effects were reported during the study period. The use of porcine dermal collagen as an augmentation graft in the treatment of massive rotator cuff tears is safe and, in most patients, is associated with improved clinical outcome. Randomized trials are required to assess any benefit over standard current surgical treatment regimens.

Changes in plantar pressure distribution after Achilles tendon augmentation with flexor hallucis longus transfer

Augmentation of the Achilles tendon with flexor hallucis longus is an established method to treat neglected ruptures and severe cases of chronic tendinopathy. After transfer of the muscle/tendon, good pain reduction and improved plantar flexion have been reported. To date, only one study has investigated the effect of FHL transfer on forefoot biomechanics. Theoretically, there should be a partial transfer of forefoot loading towards the lateral metatarsal heads during push-off, resulting in an asymmetric gait. 13 patients were examined clinically and using pedobarography with a mean follow-up of 46 months (minimum 24) after Achilles tendon augmentation with flexor hallucis longus. Parameters of the forefoot were investigated to detect differences in pressure and force distribution, load transfer to other areas of the forefoot, and asymmetries compared to the non-operated leg. The results are discussed with regard to clinical relevance. Clinically, there were no subjective or objective gait asymmetries. All patients were free of pain and without restrictions during normal walking. In general, pedobarography showed an unloading of the first toe with a load transfer to the metatarsal heads on the operated side. All results featured high inter-subject and within-subject variability. Due to the high within-subject variability, there is inconsistency within the results making interpretation difficult. However, the results confirm the hypothesis that unloading of the first toe during push-off and an asymmetrical loading pattern can be measured after harvesting of the flexor hallucis longus. The clinical situation of the patients did not reflect a visible amount of gait asymmetry. Differences in loading patterns 2 years after flexor hallucis longus transfer for Achilles tendon augmentation appear to be well compensated.

End-to-End Versus Augmented Repair in the Treatment of Acute Achilles Tendon Ruptures

We prospectively analyzed the functional and clinical results of patients who underwent a single end-to-end suture and an augmented tendon repair with plantaris tendon at middle-term follow-up. From January 2003 to May 2005, 30 consecutive patients were operated on for the treatment of acute Achilles' tendon rupture by means of 2 different methods. No cases required adjunctive procedures to allow for acceptable end-to-end apposition. All ruptures were acute and repairable. The patients were divided into 2 groups. In group 1, augmentation with plantaris tendon was performed in addition to the Krakow end-to-end suturing technique in 16 patients, and in group 2, only the Krakow end-to-end suturing technique was used in 14 patients. The average age of the patients was 40.6 years. Patients in the study groups were followed up at a mean of 17.8 months after surgery. At the end of the follow-up, functional and subjective outcome scores were evaluated. The American Orthopaedic Foot and Ankle Society hindfoot clinical outcome scores were 96.7 in group 1 and 98.8 in group 2. Although there was a numerical increase in group 2, no significant difference was determined between the 2 study groups statistically. The surgical outcome concerning local tenderness, skin adhesion scar, and tendon thickness was better in group 2 than in group 1 without a statistical significance. Although functional outcomes of both treatment groups were the same, the end-to-end suturing technique provided a safer and more reliable treatment with a low risk of complications in the treatment of acute Achilles' tendon ruptures compared with the plantaris tendon augmentation technique.

Mechanical evaluation of different techniques for Achilles tendon repair

One aim of the surgical treatment of acute Achilles tendon ruptures is to obtain a maximum primary stability of the sutured tendon. Therefore, we investigated the primary stability of sutured human Achilles tendons depending on different applied techniques. The strength of 60 repaired cadaveric human Achilles tendons was tested depending on either the suture technique (Bunnell or Kessler), the suture material (PDS-thread or PDS-cord) or an additional plantaris tendon augmentation (PDS-thread with or without augmentation). Following anatomic reconstruction the repaired specimens were loaded to failure. The use of Bunnell's technique resulted in a stronger primary suture stability compared to Kessler's technique. Sutures carried out with a PDS-thread were of lower strength than those accomplished with a PDS-cord (Bunnell: thread 139 N +/- 29.8; cord 291 N +/- 55.2/Kessler: thread 137 N +/- 37.3; cord 180 N +/- 41.1). Sutures performed according to Bunnell's technique with a PDS-thread and an additional autologous plantaris tendon augmentation reached the highest primary stability (326 N +/- 124.9). The findings identify the Achilles tendon suture with a PDS-cord according to Bunnell's technique as a mechanically strong method. A plantaris tendon augmentation in addition to a PDS-thread can even add more stability to the Achilles tendon suture.