Biomechanical properties of different techniques used in vitro for suturing mid-substance Achilles tendon ruptures

[Update on minimally-invasive treatment of Achilles tendon rupture]

BACKGROUND

Percutaneous and minimally invasive suturing techniques are very important in the treatment of acute Achilles tendon ruptures because they combine the advantages of surgical treatment (low re-rupture rate) and non-opervative treatment (low risk of complications). In the authors' approach, the percutaneous, peritendineum-preserving technique with the Dresden instrument has proven itself as a standard treatment for 20 years.

DRESDEN TECHNIQUE

Strict adherence to the original Dresden technique with posteromedial incision and subfascial preparation is crucial for the safe avoidance of the sural lesions regularly reported in percutaneous procedures. The rupture zone and the peritendineum should not be opened. By adding a third suture and using non-absorbable suture material, stability comparable to the open Krackow suture technique is achieved. Functional aftertreatment with protection in a special boot and appropriate supervision of the patient aims at early rehabilitation while minimizing the risk of re-rupture or loss of tension.

OUTLOOK

The focus of future efforts should be to further improve treatment results through individualized postoperative treatment adapted to tendon healing.

Unique case study: Impact of single-session neuromuscular biofeedback on motor unit properties following 12 days of Achilles tendon surgical repair

We explored the first evidence of a single-session neuromuscular biofeedback effect on motor unit properties, neuromuscular activation, and the Achilles tendon (AT) length 12 days after undergoing AT surgical repair. We hypothesized that immediate neuromuscular biofeedback enhances motor unit properties and activation without causing AT lengthening. After 12 days AT surgical repair, Medial Gastrocnemius (MG) motor unit decomposition was performed on a 58-year-old male before and after a neuromuscular biofeedback intervention (surface electromyography (sEMG) and ultrasonography), involving unressited plantar flexion. The analysis included motor unit population properties, sEMG amplitude, force paradigm, and AT length. There were increased MG motor unit recruitment, peak and average firing rate, coefficient of variation, and sEMG amplitude, and decreased recruitment and derecruitment threshold in the repaired AT limb. The non-injured limb increased the motor unit recruitment, and decreased the coefficient of variation, peak and average firing rate, inter-pulse interval, derecruitment threshold and sEMG amplitude. The AT length experienced -0.4 and 0.3 cm changes in the repaired AT and non-injured limb, respectively. This single-session neuromuscular biofeedback 12 days after AT surgery shows evidence of enhanced motor unit properties and activation without signs of AT lengthening when unresisted plantar flexion is performed in the repaired AT limb.

Nonoperative or Surgical Treatment of Acute Achilles' Tendon Rupture

BACKGROUND

Whether surgical repair of an acute Achilles' tendon rupture by an open-repair or minimally invasive approach is associated with better outcomes than nonsurgical treatment is not clear.

METHODS

We performed a multicenter, randomized, controlled trial that compared nonoperative treatment, open repair, and minimally invasive surgery in adults with acute Achilles' tendon rupture who presented to four trial centers. The primary outcome was the change from baseline in the Achilles' tendon Total Rupture Score (scores range from 0 to 100, with higher scores indicating better health status) at 12 months. Secondary outcomes included the incidence of tendon rerupture.

RESULTS

A total of 554 patients underwent randomization, and 526 patients were included in the final analysis. The mean changes in the Achilles' tendon Total Rupture Score were -17.0 points in the nonoperative group, -16.0 points in the open-repair group, and -14.7 points in the minimally invasive surgery group (P = 0.57). Pairwise comparisons provided no evidence of differences between the groups. The changes from baseline in physical performance and patient-reported physical function were similar in the three groups. The number of tendon reruptures was higher in the nonoperative group (6.2%) than in the open-repair or minimally invasive surgery group (0.6% in each). There were 9 nerve injuries in the minimally invasive surgery group (in 5.2% of the patients) as compared with 5 in the open-repair group (in 2.8%) and 1 in the nonoperative group (in 0.6%).

CONCLUSIONS

In patients with Achilles' tendon rupture, surgery (open repair or minimally invasive surgery) was not associated with better outcomes than nonoperative treatment at 12 months. (Funded by the South-Eastern Norway Regional Health Authority and Akershus University Hospital; ClinicalTrials.gov number, NCT01785264.).

Biomechanical comparisons of three minimally invasive Achilles tendon percutaneous repair suture techniques

BACKGROUND

While no gold standard exists for the management of Achilles tendon ruptures, surgical repair is common in healthy and active patients. Minimally invasive repair methods have become increasingly popular, while biomechanical equivalency hasn't been proven yet.

METHODS

A mid-substance Achilles tendon rupture was created 6 cm proximal to the calcaneal insertion in 27 fresh-frozen cadaveric ankles. Specimens were randomly allocated to 1 of 3 repair techniques: Huttunen et al. (2014) (1) PARS Achilles Jig System, Nyyssönen et al. (2008) (2) Achilles Midsubstance SpeedBridge™, Schipper and Cohen (2017) (3) Dresdner Instrument and subsequently subjected to cyclic loading with 250 cycles each at 1 Hz with 4 different loading ranges (20-100 N, 20-200 N, 20-300 N, and 20-400 N).

FINDINGS

After 250 cycles no significant differences in elongation were observed between PARS and Dresdner Instrument(p = 1.0). Furthermore, SpeedBridge™ repairs elongated less than either Dresdner Instrument (p = 0.0006) or PARS (p = 0.102). Main elongation (85%) occurred within the first 10 cycles with a comparable elongation in between 10 and 100 and 100-250 cycles. While all repairs withstood the first 250 cycles of cyclic loading from 20 to 100 N, only the PARS (468 ± 175) and Midsubstance SpeedBridge™ (538 ± 208) survived more cycles. Within all 3 groups suture cut out was seen to be the most common failure mechanism.

INTERPRETATION

Within all groups early repair elongation was seen. While this was least obvious within the SpeedBridge™ technique, ultimate strengths of repairs (cycles to failure) were comparable across PARS and SpeedBridge™ with a decline in the Dresdner Instrument group.

Do the heel-rise test and isometric strength improve after Achilles tendon repair using Dresden technique?

BACKGROUND

Achilles' tendon ruptures result in impaired plantar flexion strength and endurance. It is interesting to know the plantar flexion strength, the number of heel-rise repetitions, and the maximal calf circumference following Achilles' tendon ruptures repair.

METHODS

Both the injured and non-injured legs of thirty male patients with Achilles' tendon ruptures treated with the percutaneous Dresden technique were compared with the ankle function of 30 healthy participants. Rehabilitation involved partial weight-bearing for three weeks and then increased to full weight-bearing and ankle exercises.

RESULTS

The injured legs had weaker plantar flexion strength (1.64 ± 0.17 Nm/kg) compared with the non-injured legs (1.91 ± 0.24 Nm/kg; p = 0.002) and the healthy participants' legs (1.93 ± 0.32 Nm/kg; p < 0.001). The non-injured leg had greater ability in doing heel-rise repetitions (39.4 ± 6.1 rep.) compared with the injured legs (37.2 ± 5.7 rep.; p < 0.023) and the healthy participants' legs (31.0 ± 13.0 rep.; p < 0.001).

CONCLUSIONS

The injured leg had not recovered full isometric strength but had improved heel-rise repetition.

Achilles Tendon Allograft Preparation Technique for Anterior Cruciate Ligament Reconstruction: A Technical Note

Several factors associated with graft preparation for the surgery of the anterior cruciate ligament (ACL) like the wrong thawed, prophylaxis, bone cuts, excessive bone removal as well as positioning problems like a tunnels-graft mismatch, insufficient harvesting of the donor's tendon, size graft limitations (length and diameter), uncontrolled rotation of graft in their longitudinal axis, over or under tensioned graft, fixation mistakes, bone defects, secondary arthrofibrosis or morbidity of the donor site, and others factors importantly affect the outcomes of the ACL surgery. In this sense, the Achilles tendon Allograft is an advantageous technique where many of the previous limitation factors described can be controlled during an appropriate preparation. However, to obtain the maximum potentialities of the graft a detailed knowledge of the preparation is required. Hence, we aimed to describe how to prepare the Achilles tendon Allograft to control the graft's length and diameter, bone removal, and fixation requirements.

The elastic capacity of a tendon-repair construct influences the force necessary to induce gapping

PURPOSE

Most biomechanical investigations of tendon repairs were based on output measures from hydraulic loading machines, therefore, accounting for construct failure rather than true gapping within the rupture zone. It was hypothesized that the elastic capacity of a tendon-repair construct influences the force necessary to induce gapping.

METHODS

A tendon-repair model was created in 48 porcine lower hind limbs, which were allocated to three fixation techniques: (1) Krackow, (2) transosseous and (3) anchor fixation. Loading was performed based on a standardized phased load-to-failure protocol using a servohydraulic mechanical testing system MTS (Zwick Roell, Ulm, Germany). Rupture-zone dehiscence was measured with an external motion capture device. Factors influencing dehiscence formation was determined using a linear regression model and adjustment performed as necessary. A 3-mm gap was considered clinically relevant. Analysis of variance (ANOVA) was used for comparison between groups.

RESULTS

The elastic capacity of a tendon-repair construct influences the force necessary to induce gapping of 3 mm (F_3mm) [β = 0.6, confidence interval (CI) 0.4-1.0, p < 0.001]. Furthermore, the three methods of fixation did not differ significantly in terms of maximum force to failure (n.s) or F_3mm (n.s).

CONCLUSION

The main finding of this study demonstrated that the higher the elastic capacity of a tendon-repair construct, the higher the force necessary to induce clinically relevant gapping.

LEVEL OF EVIDENCE

Controlled biomechanical study.