Ex vivo biomechanical evaluation of extracapsular stabilization with quasi-isometric points in canine cranial cruciate ligament-deficient stifles

BACKGROUND

Cranial cruciate ligament (CCL) disease is one of the most common causes of lameness in dogs. The extracapsular stabilization (ECS) utilizing bone anchors and monofilament nylon leader was an alternative treatment for CCL-deficient (CCLD) dogs. However, the biomechanical response of the canine stifle to such a surgical repair strategy in conjunction with the use of recently reported quasi-isometric anchoring points remains unclear. The objectives of the study were to evaluate the mobility and stability of CCL-intact, CCLD, and CCLD stifles repaired with ECS at two different pairs of quasi-isometric points (quasi-IPs).

METHODS

Twelve stifle specimens from 7 dogs underwent mobility and stability tests under 4 different conditions, namely, CCL-intact, CCLD, and ECS-repaired at 2 different pairs of quasi-IPs (referred to as ECS-IP1 and ECS-IP2). The mobility tests evaluated 6 degrees-of-freedom stifle kinematics during flexion and extension. The stability tests involved cranial drawer and tibial internal rotation (IR) tests at various stifle opening angles and quantifying the cranial tibial translation (CTT) and tibial IR angles under constantly applied loadings.

RESULTS

The ECS repaired at quasi-IPs was shown to restore cranial instability of the stifles with averaged CTT magnitudes < 1.4 mm. During the tibial IR test, the ECS treatments resulted in significantly less tibial IR compared to those in intact CCL stifles. The mobility tests showed similar results.

CONCLUSION

The 2 chosen pairs of quasi-IPs were shown to effectively correct the excessive CTT caused by CCLD stifles, whereas the excessive tibial external rotation in comparison to those of intact stifles should be considered for its subsequent influence on joint alignment and the contact pressure applied to the stifle joint.

Conservative nonsurgical treatment for cranial cruciate ligament disease can be an effective management strategy in cats based on validated owner-based subjective assessment in some cases

OBJECTIVE

To describe long-term outcomes of cats managed medically for cranial cruciate ligament disease (CCLD) via a validated owner-based questionnaire.

ANIMALS

18 client-owned cats.

PROCEDURES

Retrospective review of medical records at 2 tertiary referral hospitals was conducted for records of cats diagnosed with CCLD for which medical management was pursued. History, physical examination findings, and medical management strategies were recorded. Owner follow-up was obtained via phone call or an email correspondence interview using a 2-part questionnaire. Part 1 consisted of 5 multiple-choice questions evaluating short-term outcomes following initiation of medical management. Part 2 assessed long-term outcomes via the validated Feline Musculoskeletal Pain Index—short form metrology instrument.

RESULTS

Mean follow-up time was 66.5 ± 46.7 months (range, 7 to 154 months). Medical management included oral analgesics, activity restriction, and joint supplements. Of the 18 cats, 13 (72%) were always able to bear weight or became weight bearing within a week following initiation of medical management, and 15 (83%) were reportedly clinically normal within 3 months of initiating medical management, with complete resolution of lameness occurring in less than 2 months in 12 of those cats. Long term, 17 of the 18 (94%) owners reported they felt that their cat had a good to excellent outcome with medical management. The mean Feline Musculoskeletal Pain Index—short form score of all cats was 0.29 ± 0.53 (range, 0 to 2.13).

CLINICAL RELEVANCE

Based on owner follow-up, conservative, nonsurgical management of CCLD can be an effective and appropriate management strategy for some cats; however, some may be best treated with surgical stabilization.

Tibial tuberosity transposition advancement for treatment of concomitant cranial cruciate ligament rupture and medial patellar luxation in four feline stifles

Case series summary

Three cats (four stifles) were diagnosed with varying grades of medial patellar luxation and stifle instability in cranial tibial thrust. Radiographs showed periarticular osteophytosis, intra-articular mineralization and opacification encroachment of the infrapatellar fat pad. Stifle exploration revealed either partial (n = 2) or complete (n = 2) cranial cruciate ligament tear and medial meniscal injury in all cases. Medial meniscectomy, partial parasagittal patellectomy, femoral trochleoplasty and tibial tuberosity transposition advancement using a 6 mm cage, two-fork plate and 4 mm spacer were performed in four stifles. Screws (2.0 mm) and washers were used in the cranial cage ears rather than conventional 2.4 mm screws. By the 2-week recheck, lameness was minimal and stifles were stable. Radiographic follow-up at 8 weeks showed appropriate progression of osseous union in all cases. One cat experienced a major complication, suffering tibial fracture following a lapse in exercise restriction, and revision surgery was performed successfully with subsequent osseus union of the osteotomy site. At the mid-term follow-up, all cats had a return to previous level of function, as assessed by both owner questionnaire and clinical evaluation.

Relevance and novel information

Tibial tuberosity transposition and advancement has been shown to be successful in dogs for the treatment of concomitant medial patellar luxation and cranial cruciate ligament rupture. To date, there have been no reports of tibial tuberosity transposition and advancement in cats. A benefit of this approach is concomitant alignment of the extensor mechanism and neutralization of the femorotibial shear force. Our case series describes successful use of tibial tuberosity transposition advancement in cats.

Comparison of Extracapsular Stabilization Techniques Using an Ultrasonically Implanted Absorbable Bone Anchor (Weldix) after Cranial Cruciate Ligament Rupture in Cats-An In Vitro Study

Simple Summary

One reason for lameness in cats is the rupture of the cranial cruciate ligament. This ligament is located in the stifle joint and contributes to its stabilization during excessive forward movement and internal rotation of the tibia. One method for the surgical treatment of cranial ligament rupture is the placement of an extracapsular suture. Different materials and methods of suture fixation have been used in dogs and cats. This study investigated the use of a novel polylactide absorbable bone anchor that was implanted with ultrasound technology for suture fixation and compared this with suture fixation alone and fixation with a nonabsorbable bone anchor using an ex vivo modified limb-press model. For evaluation, distance measurements on radiographs were performed and the angles between defined bony structures were calculated. The acquired measurements accounted for both craniocaudal and mediolateral movements, and the results showed that the absorbable anchor could neutralize excessive movement within the stifle joint in two of three measurements and seems to be a good alternative to well-known surgical methods.

Abstract

Background: This study evaluated joint stability after surgical repair of cranial cruciate ligament (CrCL)-deficient stifle joints in cats using a novel absorbable polylactide bone anchor in an ex vivo model. Methods: Thirty-six hindlimbs from cats with intact (G_i group) and transected CrCLs were treated with fabellotibial suture alone (G_FW group), suture combined with an absorbable polylactide bone anchor (G_WD group), or suture combined with a nonabsorbable bone anchor (G_FT group), positioned in a limb press with predefined joint angles (stifle joint: 120 ± 5°; hock joint: 120 ± 5°) and loaded with 10%, 20%, and 30% of body mass (BM). Predefined points were measured on lateral radiographs and with a coordinate measurement machine. Distances on radiographs (mm) were measured and angles (°) were calculated to represent the craniocaudal movement and the internal rotation of the tibia. Results: There were no differences for craniocaudal movement between G_i and G_FW or G_FT, but for G_WD regarding angle measurement at 30% BM. For internal rotation, there was no significant difference between G_i and G_FW or G_WD, but for G_FT. Conclusion: The used absorbable polylactide bone-anchor was able to stabilize the stifle joint regarding internal rotation and craniocaudal movement as calculated from distance measurements.

Comparison of a novel extracapsular suture technique with a standard fabellotibial suture technique for cranial cruciate ligament repair using a custom-made limb-press model in cats

OBJECTIVES

The aim of our study was to compare the standard fabellotibial suture with Mini TightRope fixation for the treatment of a cranial cruciate ligament (CCL) rupture using a feline custom-made limb press.

METHODS

Cadaveric hindlimbs of 10 cats were inserted in the limb press at predefined joint angles and loads of 10% and 30% body weight (BW) were applied. Mediolateral radiographs were taken and three-dimensional coordinates were recorded using a microscribe digitiser, with intact and transected CCLs and after either fabellotibial suture or Mini TightRope fixation were performed. Different distances and angles from radiographs or microscribe coordinates were analysed.

RESULTS

Radiographic distances from the femoral condyle to the cranial edge of the tibia (X1-X2) were higher in CCL-deficient stifles than in intact stifles at 10% and 30% BW loads. All fabellotibial sutures and Mini TightRope fixations neutralised excessive cranial tibial thrust. A significant difference in the distance between the patella and tibial tuberosity (D2) was observed between CCL-deficient limbs and Mini TightRope-fixed limbs at 10% BW load (P <0.04). A significant difference in the distance between the tibial tuberosity and lateral collateral ligament of the femur (D3) was observed between the intact and transected CCLs on the left legs at 10% BW load (P <0.003) and on both legs at 30% BW load (P <0.002). Furthermore, we observed significant differences between CCL-deficient left legs and Mini TightRope-treated legs at 10% BW load (P <0.003). With regard to fabellotibial suture-treated legs, we observed significant differences between transected limbs and fixed limbs at 30% BW load (P <0.004). W1 (craniocaudal angle) and W2 (mediolateral angle) showed significant differences between intact and transected CCLs and between transected and fixed limbs at 30% BW load (P <0.004).

CONCLUSIONS AND RELEVANCE

Fixation of CCL-deficient stifles with lateral fabellotibial suture, as well as Mini TightRope tightened with a 20 N load, produces good biomechanical stability, as detected via radiographic assessment.

Clinical Outcomes and Stifle Osteoarthritis Assessment of Nine Cats Before and After Tibial Plateau Levelling Osteotomy

This study aimed to evaluate the clinical and radio graphical outcome of cats following TPLO surgery for cranial cruciate ligament deficiency. Each cat underwent orthopedic assessment, pre-operative radio graphical evaluation, surgical procedure, postoperative management and clinical re-examination 1, 2, and 12 months following surgery. Age, body weights, TPAs, meniscal tears, implants and osteoarthritis progression were recorded. Postoperative OA score was compared with that obtained 1 year after surgery using a paired t-test with commercially available software. Radio graphical evaluation performed 1 year after surgery showed no significant OA progression (P-value > 0.1). Minor complications occurred in one case (#7) in which a mild to moderate seroma was observed ten days after surgery. No major complications were recorded. Although TPLO surgery in cats remains controversial, this study suggests that it was a suitable option for surgical treatment of feline cranial cruciate ligament rupture, but considering the ex vivo outcomes recently published, further in vivo evaluation is strongly recommended.

Cranial cruciate ligament disease in cats: an epidemiological retrospective study of 50 cats (2011-2016)

OBJECTIVES

The aim of this study was to describe the characteristics and long-term outcome of surgically and conservatively treated cats with cranial cruciate ligament disease (CCLD).

METHODS

A retrospective cohort study of cats with CCLD, diagnosed at two university animal hospitals between January 2011 and December 2016, was performed. Signalment, history, treatment and follow-up information were retrieved. Cat owners were contacted for additional long-term follow-up information. The cases were divided into two groups: one conservatively managed and one surgically treated with the lateral fabellotibial suture technique. A quality of life questionnaire, the Feline Musculoskeletal Pain Index (FMPI), was distributed to the owners of cats alive at follow-up for assessment of chronic pain as a long-term outcome. Univariable statistical methods were used to evaluate the data.

RESULTS

Fifty cats were identified and were followed for a median of 41 months after diagnosis of CCLD. Seven cats (14%) developed bilateral CCLD. Twenty-eight cats (56%) were treated conservatively and 22 (44%) surgically. All surgically treated cats in which arthrotomy was performed (19/22) had total cranial cruciate ligament rupture and 9/19 (47%) had meniscal injuries. Postoperative surgical complications were recorded in 6/22 cats (27%). Owners of 24/29 (83%) cats still alive at follow-up completed the FMPI questionnaire. The conservatively treated cats had a lower FMPI score, indicating less chronic pain, than those cats treated surgically (P = 0.017).

CONCLUSIONS AND RELEVANCE

Conservatively treated cats with CCLD experienced less chronic pain at long-term follow-up than surgically treated cats. Bilateral disease is not uncommon in cats with CCLD.

Management of severe stifle trauma: 1. Stifle luxation

PRACTICAL RELEVANCE

Traumatic stifle joint luxation is an uncommon but severe injury. There is usually rupture of several stabilising structures of the joint including the cruciate ligaments, collateral ligaments, joint capsule and menisci. Successful management of this condition requires good anatomical knowledge and repair or replacement of all damaged structures to achieve adequate joint reduction and stability. Better understanding of the treatment options available will aid clinical decision-making.

CLINICAL CHALLENGES

Due to the significant joint instability associated with these injuries, surgical repair is challenging. The use of a temporary transarticular pin to hold the stifle joint in anatomic reduction greatly aids ligament repair or replacement. Postoperative joint immobilisation has traditionally been recommended to protect the primary repair and aid periarticular fibrosis, but prolonged immobilisation can have deleterious long-term effects on the joint. Thus recommendations for the duration of postoperative immobilisation vary between 2 and 6 weeks. Also, due to their independent, outdoor lifestyle, affected cats may have been involved in a significant trauma with important concurrent injuries that need to be addressed prior to the orthopaedic repair.

EVIDENCE BASE

Published data is limited, with reports including only a small number of cats. The information and recommendations in this article have therefore been drawn from the available literature, the authors' experience and preliminary data from an ongoing multicentre retrospective study (unpublished).

AIMS

The aims of this article are to give the reader as thorough a summary as possible of the diagnosis, treatment, outcome and complications of traumatic stifle luxation.

Use of a custom-made limb-press model to assess intra- and extracapsular techniques for treating cranial cruciate ligament rupture in cats

Objectives This study aimed to compare the under-and-over technique, a type of intracapsular treatment, and the standard fabella-tibial suture, a method for extracapsular treatment, in achieving immediate, postoperative stifle stability after cranial cruciate ligament (CrCL) rupture by using a feline, custom-made limb-press model. Methods Cadaveric feline hindlimb specimens (n = 14) were positioned in the limb press at predefined joint angles (stifle joint: 120°; hock joint: 120°), and vertical loads of 5%, 10%, 20% and 30% body weight were applied statically. Mediolateral radiographic views were obtained of the stifles under each load before and after CrCL transection, as well as after treatment with either of the two surgical techniques, and differences in distance between two predefined radiographic points for each radiograph were analysed. Results The general linear model showed a significant effect of load ( P <0.01) and technique ( P = 0.004) and a significant interaction between load and technique ( P = 0.006) regarding craniocaudal stifle stability. Distances between predefined tibial and femoral reference points were consistently higher in transected CrCLs than in intact stifles. All standard fabella-tibial suture-treated stifles (n = 7) were stable at all loads tested. Of the seven under-and-over technique-treated stifles, one was unstable at 20% body weight load and three at 30% body weight load. Conclusions and relevance Our model, which appropriately reproduced certain aspects of domestic shorthair cat stifle mechanics, indicated that a 40 lb monofilament nylon prosthesis, tightened at 20 N, produces more favourable biomechanical stabilisation of craniocaudal cruciate-related stifle instability than a 0.5 cm wide strip of fascia lata applied intracapsularly.

Effect of tibial tuberosity advancement on cranial tibial subluxation in the feline cranial cruciate deficient stifle joint: An ex vivo experimental study

The effects of Tibial Tuberosity Advancement (TTA) on Cranial Tibial Subluxation (CTS) and Tibial Rotation Angle (TRA) were evaluated in a model of feline Cranial Cruciate Ligament (CrCL)-deficient stifle joint. Ten hindlimbs of adult cats were used. Quadriceps and gastrocnemius muscles were simulated using cables, turnbuckles and a spring. An axial load of 30% body weight was applied. The stifle and talocrural joint angles were adjusted to 120°. Patellar tendon angle (PTA), CTS and TRA were measured radiographically before and after CrCL section, after TTA and after additional advancement by 1 and 2mm. CrCL section resulted in a CTS of 8.1±1.5mm and a TRA of 18.4±5.7 °. After TTA, PTA was significantly decreased from 99.1±1.7° to 89.1±0.7°; CTS and TRA did not change significantly (7.8±1.0mm and 15.9±5.7° respectively). Additional advancement of the tibial tuberosity by 1mm did not significantly affect CTS and TRA. Additional advancement of the tibial tuberosity by 2mm significantly reduced the PTA to 82.9±0.9°. A significant decrease of CTS (6.9±1.3mm) and TRA (14.7±3.6°) was also observed. A lack of stabilization of the CrCL deficient stifle was observed after TTA in this model of the feline stifle. Even though the validity of the model can be questioned, simple transposition of the technique of TTA from the cat to the dog appeared hazardous.