Biomechanical comparison of knotted and knotless stabilization techniques of the tarsal medial collateral ligament in cats: A cadaveric study.

OBJECTIVE: To compare mechanical properties of intact feline medial collateral ligaments and three techniques for treatment of feline medial tarsal instability. STUDY DESIGN: Controlled laboratory study. SAMPLE POPULATION: Forty-eight normal, adult feline tarsi. METHODS: Three repairs were tested: a bone tunnel with polypropylene (PP) suture, a bone tunnel with polyethylene (PE) cord, and a knotless anchor technique with PE cord. A cyclic (6-N preload; 5-N amplitude; 2-Hz frequency) tensile test (600 cycles) was performed on feline tarsi with either the long or the short medial tarsal ligament intact, with each reconstruction technique followed by a single-cycle load-to-failure test (0.5 mm/s) with a failure point at 2 mm of displacement. Total elongation, peak-to-peak elongation, stiffness, and maximum load to failure point were compared with the intact condition. RESULTS: No differences in stiffness, total elongation, or peak-to-peak elongation were found between specimens repaired with the knotless technique and intact controls (P > .04), whereas tarsi repaired with the tunnel technique and PP were weaker (P < .008). Total and conditioning elongation were greater after tunnel reconstruction with PP than after knotless reconstruction (P = .005). Mean load to 2 mm of displacement tended (P = .03) to be higher after knotless than after knotted PP repairs and did not differ (P = .47) between tarsi repaired with the tunnel or anchor repairs with PE. CONCLUSION: The mechanical properties of intact tarsi were superior to those of tarsi repaired with tunnel techniques and PP but were similar to those of tarsi repaired with knotless techniques with PE. CLINICAL SIGNIFICANCE: Feline tarsal stabilization with the knotless technique for tarsal medial collateral ligament insufficiency may reduce the requirement for or duration of postoperative coaptation.

Ex vivo mechanical properties of a 2.5-mm bone anchor for treatment of cranial cruciate ligament rupture in toy breed dogs.

OBJECTIVE: To determine the mechanical pull-out properties of a 2.5-mm bone anchor implanted in ex vivo femurs of toy breed dogs and to determine whether there is a difference between knotted and knotless configurations. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Eight paired harvested femurs. METHODS: Femurs were assigned to knotted or knotless configuration. Equal numbers of right and left femurs were tested. The caudolateral femoral condyle at the distal pole of the lateral fabella (F2 site) was drilled. The assigned configuration with braided suture combined with the bone anchor was implanted into the F2 site. Each configuration was positioned into a mechanical testing machine to measure yield load, load at 3-mm displacement, ultimate load, stiffness, and mode of failure at the beginning of the canine standing phase angle (150°). RESULTS: Mean ultimate load was 100.14 and 88.69 N (P = .798), mean yield load was 59.72 and 55.85 N (P = .708), load at 3-mm displacement was 46.72 and 43.33 N (P = .656), and stiffness was calculated to be 43.06 and 47.09 N/mm (P = .548) for knotted and knotless configurations, respectively. Mode of failure occurred primarily by anchor pull-out. CONCLUSION: The bone anchor withstood deformation at the estimated forces applied on the native cranial cruciate ligament (CCL) of toy breed dogs in both configurations. CLINICAL SIGNIFICANCE: This bone anchor may constitute a useful alternative for stabilization of the CCL deficient stifle in toy breed dogs. However, before it can be recommended for widespread use in dogs, closely monitored clinical trials must be conducted to assess outcome and complications associated with this implant.

Changes in rima glottidis area and lack of laryngeal epiglottic-glottic seal after unilateral cricoarytenoid lateralization ex vivo.

OBJECTIVE: To evaluate variation in rima glottidis (RG) area and lack of epiglottic-glottic seal (LEGS) of the canine larynx associated with different suture anchor points in the arytenoid and cricoid cartilages, dissection of the cricoarytenoid joint capsule, section of the interarytenoid band, and disarticulation of the cricothyroid joint. STUDY DESIGN: Experimental study. ANIMALS: Cadaveric canine larynges (n = 18). METHODS: Larynges were assigned to 2 groups: group 1 = intact cricothyroid articulation and group 2 = cricothyroid articulation sharply sectioned. In each group, the arytenoid cartilage was lateralized successively as follows: (a) intact cricoarytenoid articulation, (b) cricoarytenoid articulation sharply sectioned, and (c) division of the interarytenoid band. Each variation was performed initially with the suture passed dorsally into the cricoid cartilage then with the suture passed laterally. Each time, the increase of rima glottis area (%) and the LEGS (mm(2) ) were measured. RESULTS: Rima glottis area (RGA): when the suture was placed dorsally, division of the interarytenoid band resulted in a significant increase in RGA compared with groups with an intact band. Laryngeal distortion: when the suture through the cricoid cartilage was dorsal, LEGS increased with section of the cricothyroid articulation, dissection of cricoarytenoid articulation, and division of the interarytenoid band. CONCLUSION: Unilateral arytenoid lateralization results in some degree of LEGS with a misalignment of the epiglottis over the RG. Our results revealed that the optimal RGA associated with the minimal LEGS was obtained with dorsal placement of a cricoarytenoid suture when the cricothyroid joint and the interarytenoid band were intact.

Treatment of a coxofemoral luxation in a pony using a prosthetic capsule technique.

OBJECTIVE: To report open reduction and joint stabilization using a prosthetic capsule technique for treatment of a craniodorsal coxofemoral luxation in a lightweight pony. STUDY DESIGN: Clinical report. ANIMALS: Pony stallion (8 years old, 113 kg). METHODS: A craniodorsal approach to the coxofemoral joint was performed under general anesthesia. After open reduction, a prosthetic capsule technique was used. Four 3.5 mm self-tapping cortical anchor screws were implanted: 2 screws were inserted above the cranial aspect of the dorsal acetabular rim, and 2 screws were inserted into the femoral neck. Subsequently, a #5 USP ultra-high molecular weight polyethylene suture was placed through these anchor screws in figure-8 fashion to serve as a prosthetic capsule. Routine closure and a medial patellar desmotomy completed the surgical procedure. Postoperatively, the pony was cross tied for 4 weeks to prevent it from lying down. RESULTS: Neither short-term nor long-term complications occurred and the pony was sound at the follow-up examination performed 15 months postoperatively. CONCLUSIONS: A prosthetic capsule technique can be used successfully to stabilize the coxofemoral joint after open reduction of a craniodorsal luxation in a lightweight pony.

Extra-articular stabilization of the cranial cruciate deficient stifle with anchor systems.

Complete or partial rupture of the cranial cruciate ligament (CCL) is a common injury of the canine stifle. Most practicing veterinarians would agree that optimal outcome is best achieved with surgical intervention. A popular method of stabilization is an extra-articular suture stabilization. The objective of this manuscript is to describe suture placement in a more isometric position as compared to traditional suture placement. A second objective is to introduce the veterinary surgeon to novel anchor products used for stabilization.

Biomechanical comparison of four prosthetic ligament repair techniques for tarsal medial collateral ligament injury in dogs.

OBJECTIVE: To compare joint stability and ultimate strength among 4 prosthetic ligament constructs for repair of tarsal medial collateral ligament (MCL) injury in dogs. SAMPLE: 13 canine cadavers (26 hind limbs). PROCEDURES: Each limb was stripped of all soft tissues except those associated with the tarsal joint and assigned to 1 of 4 prosthetic ligament constructs. The AN construct consisted of 3 bone anchors connected with monofilament nylon suture. The AU construct consisted of low-profile suture anchors connected with multifilament ultrahigh-molecular-weight polyethylene (UHMWPE) suture. The TN and TU constructs involved the creation of 3 bone tunnels and use of nylon or UHMWPE suture, respectively. Each limb underwent biomechanical testing before and after MCL transection and before and after cyclic range-of-motion testing following completion of the assigned construct. Tarsal joint stability (extent of laxity) was assessed with the joint in each of 3 positions (75°, 135°, and 165°). After completion of biomechanical testing, each limb was tested to failure to determine the ultimate strength of the construct. RESULTS: Relative to intact tarsal joints, joint laxity was significantly increased following completion of all 4 constructs. Construct type was not associated with the magnitude of change in joint laxity. Ultimate strength was greatest for the UHMWPE-suture constructs. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that all 4 constructs effectively stabilized MCL-deficient tarsal joints. Implants used for the TU, TN, and AU constructs had a lower profile than those used for the AN construct, which may be clinically advantageous. In vivo studies are warranted.

Biomechanical analysis of suture anchors and suture materials in the canine femur.

OBJECTIVE: Biomechanical analysis of acute load to failure (ALF) of 3 veterinary and 1 human suture anchor and cyclic load to failure with two suture material/suture anchor constructs in canine femoral condyles. STUDY DESIGN: Biomechanical in vitro study. SAMPLE POPULATION: Cadaveric femora from 20-30 kg dogs. METHODS: Three veterinary and 1 human suture anchor were placed in the cranial and caudal aspects of the femoral condyle and subjected to 0 degrees ALF. Anchors were loaded with 5 USP Fiberwire or 27 kg test nylon leader line (NLL) and subjected to 90 degrees cyclic testing for 10,000 cycles followed by ALF at 90 degrees. RESULTS: No significant difference in ALF for any anchor type was detected in the cranial aspect of the femoral condyle; however all veterinary anchors had higher ALF in the caudal aspect of the femoral condyle. In cyclic testing, the constructs in descending order (most cycles to least) were: (1) FlexiTwist/NLL, (2) Securos/Fiberwire, Securos/NLL, (3) IMEX/Fiberwire, IMEX/NLL, and (4) FlexiTwist/Fiberwire, Fastin/Fiberwire. Fiberwire was significantly stronger than NLL in post-cycling ALF testing. CONCLUSIONS: Veterinary anchors had higher ALF in the caudal versus cranial aspect of the femoral condyle. Except for the FlexiTwist in which NLL performed better, Fiberwire and NLL both had similar cyclic performance with each veterinary anchor type. The veterinary anchors exceeded the human anchor in ALF and cycles to failure. CLINICAL RELEVANCE: The tested veterinary suture anchors with Fiberwire or NLL may be used in the femoral condyle, preferably in the caudal aspect, and should withstand estimated loading conditions in appropriately confined postoperative canine patients.

Cranial cruciate ligament rupture in large and giant dogs. A retrospective evaluation of a modified lateral extracapsular stabilization.

Forty-two dogs weighing between 30 and 87 kg (mean body weight of 49 kg) with cranial cruciate ligament ruptures (CCLR) were treated with a modified lateral extra-capsular stabilization using braided polyester prosthetic ligament-suture anchor technique. Clinical and radiographic outcomes of 48 stifles were retrospectively evaluated with a mean follow-up of 18 months. Ten dogs had pulled out their bone anchors with no clinical relevance. Draining tracts did not appear. Despite mild radiographic progression of osteoarthritis, all of the dogs regained acceptable function of the operated limb.

Effect of Cricoarytenoid Joint Preservation and Suture Tension on Arytenoid Lateralization.

The objective of this experimental study was to evaluate the effects of cricoarytenoid (CA) joint preservation versus disarticulation on rima glottidis (RG) area with the epiglottis open and closed under both low and high suture tension. Canine cadaver larynges were used. A unilateral arytenoid lateralization (UAL) was performed with low or high suture tension and with the CA joint preserved or disarticulated. Rima glottidis area was measured with the epiglottis in an open and closed position. Results indicated that RG area was increased over baseline when UAL was performed with both low and high suture tension when the epiglottis was in an open position. High suture tension resulted in a greater increase in RG area compared to low suture tension, both when the CA was preserved and disarticulated. There was no difference in RG area when the CA was disarticulated versus preserved at either suture tension. Rima glottidis area was not significantly increased over baseline when the epiglottis was in a closed position except in the group with CA joint preservation and high suture tension. Although this study suggests that UAL can be performed with or without CA disarticulation, further studies are warranted before UAL without CA disarticulation can be recommended clinically.

Use of a novel extracapsular bone anchor system for stabilisation of cranial cruciate ligament insufficiency.

OBJECTIVES: To evaluate early clinical experiences using the novel extracapsular bone anchor Ruby system for stabilisation of the cranial cruciate ligament deficient stifle in the dog and report short-term outcome and complications for 17 clinical cases. MATERIALS AND METHODS: Seventeen dogs with cranial cruciate ligament insufficiency were treated using the Ruby system. Dogs were eligible if diagnosed via orthopaedic examination with unilateral or bilateral cranial cruciate ligament instability without any comorbidities. Subjective lameness assessments on a 0 to 4 scale were made pre-operatively and at six to eight weeks post-operatively; complications were also recorded. Lameness was also assessed on a visual analogue scale at six to eight months post-operatively. RESULTS: All cases had substantial improvement in lameness following surgery. Mean post-operative lameness grade was 1·18 (±0·53) out of 4, compared to a grade of 3·06 (±0·9) before surgery, and owner assessment at six to eight months after surgery was also positive. There were major complications that required surgical intervention in one dog. CLINICAL SIGNIFICANCE: The Ruby system is a feasible method of extracapsular stabilisation with comparable outcomes and complication rates to previously reported methods of addressing cranial cruciate ligament insufficiency. Further work is required to acquire more data on objective outcome measurement and mechanisms of failure.

Comparison of a suture anchor and a toggle rod for use in toggle pin fixation of coxofemoral luxations.

The mechanical characteristics of toggle rods and Bone Biter anchors inserted through the medial acetabular wall for toggle pin repair of coxofemoral luxations were compared in 16 canine cadaver pelves. No differences were detected in maximum load to failure, displacement at failure, or energy to failure between the two constructs. Toggle rod constructs failed primarily by breakage of the suture at the rod eyelet. All of the Bone Biter anchor constructs failed when the anchors pulled through the medial acetabular wall.

Translaryngeal percutaneous arytenoid lateralization technique in a canine cadaveric study.

OBJECTIVE: To describe the technique for translaryngeal percutaneous arytenoid lateralization (TPAL) and the effect on rima glottidis cross-sectional area using a canine cadaveric model. STUDY DESIGN: Ex vivo study. ANIMALS: Canine cadavers (n = 9). MATERIALS AND METHODS: With the aid of a laryngoscope, the larynx was visualized and a mattress suture (double-armed 2-0 polypropylene) was placed through the right arytenoid cartilage and exited the skin ventral to the jugular vein. The ends of the suture were passed through a button and tied on the skin to lateralize the right arytenoid cartilage. Digital images of the larynx were made before and after suture placement. Mean (±SD) rima glottidis cross-sectional area (mm(2) ) was calculated from the digital images and values before and after suture placement were compared using a paired t-test. A P value < 0.05 was considered significant. Change in cross-sectional area was expressed as percent increase. RESULTS: Suture placement and the degree of arytenoid lateralization was relatively consistent in all dogs. Mean (±SD) cross-sectional area of the rima glottidis was 126.3 mm(2) (±7.74) before and 172.1 mm(2) (±24.7) after suture placement (P = 0.004). Mean percent increase in cross-sectional area was 25%. CONCLUSION: The TPAL technique was effective at enlarging the rima glottidis in this canine cadaveric model. TPAL is rapid to perform and does not require specialized instrumentation. Results of this study support further investigation of the TPAL technique as an alternative to temporary tracheostomy for dogs in severe respiratory distress due to laryngeal paralysis.

Minimally invasive unilateral arytenoid lateralization in dogs: A cadaveric study.

The aim of this study was to develop a minimally invasive thyroarytenoid lateralization technique (MITAL). Eleven unilateral MITAL procedures were performed on 11 canine cadavers. Two hypodermic needles were passed through the skin into the lumen of the larynx, penetrating the thyroid and arytenoid cartilages. Suture material was passed through the needles to lateralize the arytenoid cartilage. A rigid endoscope was used to visualize needle insertion and suture material placement. A key-hole approach to the larynx was performed and the suture material was knotted on the lateral aspect of the thyroid cartilage. The change in the rima glottidis area was recorded as were the duration of the procedure and complications encountered. The landmarks for needle insertion were easily palpated, and a significant increase in the area of the rima glottidis was documented after performing unilateral MITAL. In conclusion, unilateral MITAL is a quick, minimally invasive procedure which increases the area of the rima glottidis in cadaveric dogs.

Tibial anatomy in normal small breed dogs including anisometry of various extracapsular stabilizing suture attachment sites.

OBJECTIVES: To investigate proximal tibial anatomy and its influence on anisometry of extracapsular stabilizing sutures in small dog breeds. MATERIALS AND METHODS: Mediolateral radiographs of the femora, stifles, and tibiae of 12 small breed dogs were acquired with the stifles positioned at various angles. Measurements taken included tibial plateau angle (TPA), diaphyseal: proximal tibial angle (DPA), patellar tendon angle (PTA), Z-angle, relative tibial tuberosity width (rTTW), and the distance between six combinations of two femoral and three tibial extra-capsular stabilizing suture (ECS) attachment sites. Theoretical strain through stifle range-of-motion was recorded. RESULTS: The TPA (32° ± 5.8°), DPA (10.2° ± 7.3°), PTA (103.7° ± 6.2°), and Z-angle (70.4° ± 9.0°) were positively correlated with one another (R >0.7), but none were correlated with rTTW (0.93 ± 0.10). The F2-T1 combination of ECS attachment sites had lowest strain for nine stifles. The shortest attachment site separation was at a stifle flexion of 50° for nine stifles. Proximal tibial anatomy measurements could not predict optimal attachment site combination, optimal stifle angle for suture placement, or ECS strain. CLINICAL SIGNIFICANCE: There is individual variation in the optimal attachment site combination and stifle angle for suture placement, which may influence consistency of outcomes with ECS.

In vitro mechanical evaluation and comparison of two crimping devices for securing monofilament nylon and multifilament polyethylene for use in extracapsular stabilization of the canine stifle.

OBJECTIVE: To compare the tensile strength and stiffness of non-absorbable suture loops created with two types of crimping devices. METHODS: Loops of monofilament nylon leader line (MN) of 18 kg, 36 kg, and 45 kg multifilament polyethylene (MP) with a crimp and MP with a crimp and knot were mechanically tested to failure in quasistatic tensile loading after being created with either a wave pattern crimp device or three applications of a single crimp device. Each testing group consisted of five samples. Tensile loading to failure at a rate of 9.5 mm/s was used. Failure was defined as a sudden drop in the recorded force. RESULTS: All suture materials failed by breaking near the crimp tube with both crimp devices, with exception of the MP without knot, which slipped through the crimp tube using both devices. Sutures secured with the wave pattern crimping device were significantly stronger with a higher load yield, maximum load, displacement yield, failure displacement, and maximum displacement than the single crimp device. Loops of MP suture crimped by either device plus the addition of a surgeon's knot resulted in a significantly stronger construct than unknotted crimped MP constructs. Crimped MP combined with knot were significantly stiffer, but not stronger, than crimped 45 kg MN. CLINICAL SIGNIFICANCE: Performing extra- capsular repair for ruptured cranial cruciate ligaments with the wave pattern crimp system may result in lower failure rates due to the construct being significantly stronger than the single crimp system.

Mechanical properties of isolated loops of nylon leader material, polyethylene cord, and polyethylene tape and mechanical properties of those materials secured to cadaveric canine femurs via lateral femoral fabellae, toggles placed through bone tunnels, or bone anchors.

OBJECTIVE: To determine mechanical properties of various prosthetic materials secured to cadaveric canine femurs via various methods and to compare results with those for isolated loops of prosthetic material. SAMPLE: 80 femurs obtained from cadavers of skeletally mature large-breed dogs. PROCEDURES: 10 femoral constructs in each of 8 groups (single circumfabellar loop of polyethylene cord, double loop of polyethylene tape secured via a bone anchor [BAPT], single or double circumfabellar loops of nylon leader material [CNL] or polyethylene tape [CPT], or single or double loops of polyethylene tape secured via a toggle placed through a bone tunnel [BTPT]) and 10 isolated loops of prosthetic material in each corresponding configuration were tested. Stress relaxation, creep, elongation, load at 3 mm of displacement, stiffness, and peak load at failure were determined. RESULTS: 5 single CNL constructs failed before completion of testing. Double CNL and single circumfabellar polyethylene cord constructs had the lowest loads at 3 mm of displacement. Single and double CPT constructs had the highest stiffness. Double BTPT and CPT constructs had the highest peak loads at failure. Double BTPT, double CPT, and BAPT constructs were mechanically superior on the basis of lower creep and stress relaxation and higher stiffness and load at 3 mm of displacement versus other constructs. Stiffness of femoral constructs was 28% to 69% that of corresponding isolated prosthetic loops. CONCLUSIONS AND CLINICAL RELEVANCE: Double BTPT, double CPT, and BAPT constructs were mechanically superior to other constucts. Mechanical properties and methods of anchorage and securing of free ends of prostheses contributed to mechanical properties of constructs.