Minimally invasive ultrasound-assisted cutting thread tenotomy of the deep digital flexor tendon in horses: An ex vivo study.

OBJECTIVE: To evaluate the feasibility and limitations associated with a minimally invasive ultrasound-assisted cutting thread technique for tenotomy of the deep digital flexor tendon (DDFT) in horses. STUDY DESIGN: Ex vivo study. SAMPLE POPULATION: Twenty cadaveric forelimbs. METHODS: Forelimbs were placed on a jig to mimic a standing semiflexed position and the midmetacarpal region was prepared to perform tenotomy of the DDFT using a percutaneous technique with a cutting thread. For that purpose, the thread was placed percutaneously around the DDFT (first dorsally and then palmarly) with the aid of a curved 20 gauge spinal needle. Tendon palpation/manipulation and ultrasonographic assessment assisted thread placement. Procedure time and skin puncture size were recorded. Limbs were then dissected to evaluate the degree of DDFT transection and the presence of any iatrogenic lesions. RESULTS: The DDFT was completely transected in all cases. Minor lesions of the superficial digital flexor tendon were found in 11/20 limbs and considered clinically irrelevant. However, the neurovascular bundle was damaged in 6/20 limbs (four limbs had nerve damage and two limbs had a nerve and either a palmar artery or vein damaged). The skin puncture hole sizes ranged from undetectable to 5 mm long. The average duration of the procedure was 7 min and 38 s (range: 4 min 56 s to 10 min 19 s). CONCLUSION: A DDFT tenotomy can be performed reliably with a percutaneous cutting thread technique. However, refinement of the technique is required to minimize iatrogenic damage. CLINICAL SIGNIFICANCE: The reported technique allows a DDFT tenotomy to be performed in a minimally invasive manner and has the potential to be clinically applicable.

Effect of single and double hemitenotomy on equine deep digital flexor tendon length and strength in experimental load challenges.

OBJECTIVE: To evaluate a double hemitenotomy (DHT) technique as an alternative to complete deep digital flexor (DDFT) tenotomy. STUDY DESIGN: Experimental ex vivo study. SAMPLE POPULATION: Isolated DDFTs (n = 30) and cadaveric forelimbs (n = 16). METHODS: In part 1, 15 isolated DDFT pairs were used. Two hemitenotomies were created in 1 DDFT while the other served as reference. Monotonic tensile load was applied. Tendon lengthening, load reduction, and load at failure were recorded. In part 2, 16 cadaveric forelimb pairs were subjected to DHT followed by complete tenotomy (CT) under monotonic compressive load. Differences between DHT and controls were assessed with Wilcoxon signed rank tests or Friedman tests. RESULTS: In isolated tendons and cadaveric forelimbs, DHT resulted in DDFT lengthening (median, +1.9 mm and + 3.05 mm) and load reduction (median, -16.7 and -11.2 kg). Less lengthening was achieved with DHT compared to CT (P = .008). Load reduction did not occur between DHT and CT was observed during compressive testing (P = 1). Load reduction following the first hemitenotomy incision was smaller when compared to the second (P = .022). Isolated DHT tendons failed at a tensile load of 195 kg, while no intact tendons failed (P = .0001). CONCLUSION: Double hemitenotomy was comparable to CT in load reduction. It reduced tensile strength, but load at failure was similar or exceeded the estimated DDFT load at stance. CLINICAL SIGNIFICANCE: Hemitenotomy may be a useful alternative for surgical management of horses with laminitis, but in vivo studies are needed to confirm these findings.

Biomechanical evaluation of a novel barbed suture pattern with epitendinous suture augmentation in a canine flexor tendon model.

OBJECTIVE: To determine the effect of a novel barbed suture pattern (NBSP) compared to a three-loop-pulley (3LP) with and without epitendinous suture (ES) augmentation on the biomechanical strength and gap formation of repaired canine tendons. STUDY DESIGN: Ex vivo, cadaveric, randomized, experimental study. SAMPLE POPULATION: Forty, adult superficial digital flexor tendons (SDFT). METHODS: SDFT were randomly assigned to one of four groups (n = 10/group). Sharp tenotomy was performed and repaired with 3LP, NBSP, 3LP + ES, and NBSP + ES. Constructs were tested to failure while evaluating yield, peak, and failure loads, loads at 1 and 3 mm gap formation, and failure mode. RESULTS: Constructs augmented with ES sustained 80% greater yield (p < .001), peak (p < .001), and failure (p < .001) loads, with no difference between 3LP + ES and NBSP + ES constructs regarding peak (p = .614), and failure forces (p = .865). Loads resulting in 1 and 3 mm gap formation were greater when constructs were augmented with an ES (p ≤ .003). Failure mode differed between groups (p < .001), occurring predominantly due to suture pull-through in 3LP and NBSP groups compared to tissue failure distant to the repair site in ES augmented constructs. CONCLUSION: Tendons repaired with the NBSP used in this study resisted similar forces as those repaired with 3LP. Augmentation with an ES improved the biomechanical properties of repaired constructs, including resistance to gap formation. CLINICAL RELEVANCE: The NBSP repair tested here may be advantageous over monofilament suture repair as it uses a similar-sized barbed core suture but eliminates the requirement for knot tying.

Minimally invasive tenotomy of the tibial insertion of the semitendinosus muscle: An ex vivo study in horses.

OBJECTIVE: To describe a minimally invasive technique for semitendinosus tenotomy with ultrasonographic guidance and to evaluate procedural complications. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Cadaveric equine hind limbs (n = 16). METHODS: A stab incision was performed distocaudal to the tibial insertion of the semitendinosus muscle with ultrasonographic assistance. After transection of the tendon with an arthroscopic retrograde knife, the tendon edges palpably retracted, and complete transection was confirmed by ultrasound. Limbs were dissected to confirm the degree of tendon transection and to identify iatrogenic trauma to surrounding soft tissues. RESULTS: Tenotomy was complete in all limbs, resulting in a palpable gap forming between tendon edges. Superficial iatrogenic laceration to the underlying gracilis muscle (n = 2) or gracilis fascia (n = 1) was apparent in 3 of 16 limbs. CONCLUSION: Ultrasound-assisted tenotomy of the tibial insertion of the semitendinosus muscle was reliably performed in a minimally invasive fashion with minor iatrogenic damage. CLINICAL SIGNIFICANCE: Minimally invasive tenotomy of the semitendinosus muscle can be performed with ultrasonographic assistance and should be considered as an alternative technique for surgical management of fibrotic semitendinosus myopathy.

Arthroscopic tenotomy for treatment of biceps tendon luxation in two apprehension police dogs.

CASE DESCRIPTION: A 7.5-year-old 37.8-kg (83.2-lb) sexually intact male German Shepherd Dog (dog 1) and a 2.6-year-old 28.2-kg (62.0-lb) sexually intact male Dutch Shepherd (dog 2), both apprehension police dogs, were admitted for evaluation of left and right thoracic limb lameness, respectively. CLINICAL FINDINGS: In both dogs, signs of pain were elicited on palpation of the shoulder joint in the affected limb, and a distinct popping of the biceps brachii tendon (BT) was palpable on the craniomedial aspect of the affected joint on flexion and extension and was associated with moderate signs of pain. Biceps brachii tendon luxation (BTL) was diagnosed with dynamic musculoskeletal ultrasonography (both dogs) and MRI (dog 1). TREATMENT AND OUTCOME: Arthroscopic BT release by tenotomy was performed in both dogs. Lameness appeared to have resolved by 8 weeks after surgery and had not recurred by the last follow-up communications at 36 and 9 months after surgery for dogs 1 and 2, respectively. Both dogs successfully returned to their level of work performed before their injury. CLINICAL RELEVANCE: Our findings for the dogs of the present report suggested that arthroscopic BT release could be considered a viable treatment option for BTL in dogs, including police dogs or other high-performance athletic dogs. Although our findings provided encouraging results, further research, best conducted with a multicenter prospective randomized study, would be needed to establish the most reliable treatment of BTL in high-performance athletic or working dogs.

Tenotomy of the semitendinosus muscle under standing sedation versus general anesthesia: Outcomes in 20 horses with fibrotic myopathy.

OBJECTIVE: To compare outcomes after semitendinosus tenotomy performed under standing sedation versus general anesthesia. STUDY DESIGN: Retrospective case series. SAMPLE POPULATION: 20 horses with fibrotic myopathy of the semitendinosus muscle. METHODS: Medical records (2002-2015) of horses undergoing tenotomy of the semitendinosus muscle for the treatment of fibrotic myopathy were reviewed. Signalment, history, affected muscles, restrain method, surgical procedures, and short-term outcome as well as complications were retrieved from records. Long-term outcome (gait and athletic function) was assessed at least 6 months postoperatively by conversation with the owners. Pearson's χ2 statistical analysis was used to compare restrain method and affected muscles with overall outcome. Significance was set at P < .05. RESULTS: Tenotomy of the semitendinosus muscle was performed under standing sedation in 8 horses and under general anesthesia in 12 horses. Follow-up period ranged from 9 months to 10 years. Gait was improved to variable degrees in 8 of 14 horses when the semitendinosus muscle alone was affected and in 4 of 6 horses when both the semitendinosus and semimembranosus muscles were involved (P = .11). Six of 8 horses treated under standing sedation and 6 of 12 horses treated under general anesthesia exhibited some improvement in the characteristic fibrotic gait (P = .4473). Five of 6 athletic horses treated under standing sedation and 6 of 9 athletic horses treated under general anesthesia returned to their preinjury level of athleticism. Horses treated under standing sedation had no incisional complications; 2 of 12 horses treated under general anesthesia exhibited incisional drainage. CONCLUSION: Tenotomy of the semitendinosus muscle in horses with fibrotic myopathy leads to similar improvement in gait, whether performed under standing sedation or general anesthesia.

Arthroscopic biceps ulnar release procedure (BURP): technique description and in vitro assessment of the association of visual control and surgeon experience to regional damage and tenotomy completeness.

OBJECTIVES: (1) Describe arthroscopic BURP surgical technique, (2) assess association of visual control and surgeon experience to tenotomy completeness and regional iatrogenic tissue damage. STUDY DESIGN: Cadaveric study. SAMPLE POPULATION: Canine cadavers weighing >20 kg (n = 16; 32 elbows). METHODS: Phase 1 = dissection/anatomic description/procedural refinement (n = 6). Phase 2 = technique description (n = 6). Phase 3 = association of surgeon experience and procedural visual control to tenotomy completion and regional iatrogenic damage (n = 20). Elbows were randomly assigned via coin toss to an experienced- or inexperienced-arthroscopist. Using conventional medial portals, surgeons sought to identify the medial collateral ligament (MCL) and ulnar insertion of the biceps tendon (uBT) before attempting complete tenotomy. Upon procedural completion, surgeons assigned a standardized "visual control score" (VCS) describing viewing that governed procedure and predicted % uBT release, MCL, and median nerve damage. Post-procedural dissection determined actual tenotomy completion and iatrogenic tissue damage. RESULTS: Complete BURP was achieved in 16 of 19 elbows. VCS was associated with tenotomy completeness (P < .01). "Blind" BURP was incomplete in both elbows in which it was attempted. Perception of complete BURP was associated with complete release (P < .01). MCL damage occurred in 10% of elbows. Surgeon experience did not influence VCS, regional damage, or BURP completeness. CONCLUSION: In canine cadavers, arthroscopic BURP can be consistently performed using conventional arthroscopic instruments and portals by both experienced and inexperienced arthroscopists when visual control guides the tenotomy into the distal aspect of the tendon.