Tibial Tuberosity Advancement Research Articles

Ultrasound and Elastosonographic Features of the Patellar Ligament in Dogs Affected by Cranial Cruciate Ligament Disease.

This study aims to evaluate the morpho-functional change in the patellar ligament in dogs with cranial cruciate ligament disease. We hypothesized that it may show increased thickening and stiffness with increasing days from onset to diagnosis instead of trauma. Understanding this aspect has implications for the choice of timing for treating patients suffering from cranial cruciate ligament disease, as well as the contextualization of patellar ligament desmitis pictures after surgical treatment with tibial plateau leveling osteotomy or tibial tuberosity advancement. Thirty-three dogs affected by unilateral cranial cruciate disease were examined and divided into three groups based on the time elapsed from the onset of lameness to diagnosis: Group 1 (1-15 days), Group 2 (16-60 days), and Group 3 (over 60 days). Conventional B-mode ultrasonographic and elastosonographic examinations of the patellar ligament were performed without sedation for each dog. Upon ultrasonographic examination, all dogs showed modification in the echostructure of the patellar ligament. In addition, the patellar ligament tended to become harder with increasing days after disease, although there were no significant differences between groups. Our results show that as the time increases between the onset of cranial cruciate ligament disease and diagnosis and treatment, the patellar ligament progressively thickens and loses its elasticity.

TTA-Rapid for treating the canine cruciate deficient stifle: Medium to long-term outcome and analysis of risk factors.

This study aimed to evaluate medium to long-term outcomes following treatment of lameness associated with cranial cruciate ligament insufficiency using the tibial tuberosity advancement (TTA)-Rapid technique and to investigate risk factors associated with outcome, including tibial plateau angle (TPA). Patient records for cases treated over an 80-month period were examined retrospectively. An owner postal questionnaire using a clinical metrology instrument (Liverpool Osteoarthritis in Dogs) evaluated the outcome at least 6 months after surgery. A total of 149 procedures were carried out in 120 dogs. Questionnaires were received for 64 dogs (53.3%), with a median follow-up time of 37.5 months. Outcome was judged to be satisfactory, based on frequency of lameness, in 63 (98.4%), while satisfactory outcomes were achieved in 61 (95.3%) based on severity of lameness and in 50 (78.1%) based on mobility score. Statistical analysis showed that age, bodyweight, TPA, meniscal injury and concurrent patellar surgery did not influence outcome, but time to follow-up positively correlated with mobility score. This study involved one surgeon in one centre with outcome data based on the completion of an owner questionnaire, although this used a validated clinical metrology instrument. TTA-Rapid offers a treatment option for cranial cruciate-deficient stifles with a good medium to long-term outcome, and no risk factors were identified to suggest any limitations to its use.

Pressure-Sensitive Walkway System for Evaluation of Lameness in Dogs Affected by Unilateral Cranial Cruciate Ligament Rupture Treated with Porous Tibial Tuberosity Advancement.

The aim of this study was to objectively evaluate lameness in dogs affected by a unilateral cranial cruciate ligament rupture (CrCLR) treated with porous tibial tuberosity advancement before surgery and at three different timepoints after surgery, using the GAITRite® system (version 4.9Wr), a pressure-sensitive walkway system that is able to calculate several spatiotemporal gait parameters simultaneously for each limb. The dogs walked on the pressure-sensitive walkway before (T0) and 30 (T1), 90 (T2), and 120 (T3) days after surgery. Pressure measurements (gait lameness score and total pressure index %) were collected for S (treated with porous TTA) and C (healthy contralateral limb) at T0, T1, T2, and T3 and statistically evaluated. An ANOVA test was performed to compare the data, and a value of p < 0.05 was considered significant. Twenty dogs (n = 20) of various common breeds and ages with CrCLR were enrolled in the study. The results showed that there was a statistically significant difference in the GAIT4Dog® lameness score (GLS) and TPI% between S and C for each timepoint. Statistically significant differences in the GLS and TPI% between S at T0 and S at T2 and between S at T0 and S at T3 (p < 0.001) were found. The results showed that there was a statistically significant difference in the GAIT4Dog® lameness score (GLS) and TPI% between S and C for each timepoint. Statistically significant differences in the GLS and TPI% between S at T0 and S at T2 and between S at T0 and S at T3 were found. The GLS and TPI% increased statistically significantly from 90 days after surgery compared to the preoperative measurements. Moreover, comparing the GLS and TPI% between the treated limb and the control limb showed that a statistically significant difference remained at each timepoint.

Comparison and interobserver reliability of three different methods for measuring the amount of the tibial tuberosity advancement in the preoperative planning of TTAT.

The goal of preoperative planning techniques for advancement of the tibial tuberosity is to determine the amount of advancement required to achieve a postoperative patellar tendon angle of 90° and to select the optimal wedge size to achieve this target. Three radiographic methods for determining the advancement distance for the tibial tuberosity were evaluated for comparability and interobserver reliability. Among the methods developed, we decided to include the common tangent method, the tibial anatomy-based method, and the Bielecki method. For all techniques, radiographs were taken in mediolateral projection with the knee joint flexed at 135°. Three observers with different levels of experience independently evaluated and scored the degree of osteoarthritis for each stifle, as previously described, and performed measurements of the amount of advancement of the tibial tuberosity on 33 stifles using common tangent method, tibial anatomy-based method, and Bielecki method. According to the results, the overall score for osteoarthritis in the mediolateral view was influenced by the experience of the observers, which contradicts the results from a previous study. Regarding the measurement methods used to assess advancement, poor interobserver reliability was found for common tangent method and Bielecki method, while only a slightly moderate interobserver agreement was found for tibial anatomy-based method. These results are inconsistent with data collected by Bielecki and colleagues. Moreover, measurements from common tangent method and tibial anatomy-based method were overlapping, as confirmed previously. Conversely, Bielecki method showed no agreement with the other methods included in the present study, with a significantly higher mean rank, probably due to its correction formula. Based on the results of the present study, tibial anatomy-based method has better interobserver reliability and is easier to perform according to the observers.

Prospective measurement of outcomes and complications of tibial tuberosity advancement using novel mini plates in small breed dogs.

Cranial cruciate ligament (CrCL) disease is a common orthopedic disease in canine patients. Tibial osteotomy procedures for the treatment of cranial cruciate ligament disease in small breed dogs (<15 kg) have previously been limited. A total of 22 client-owned dogs, 26 stifles, with cranial cruciate ligament disease were treated with novel mini-tibial tuberosity advancement plates. The most common intraoperative complications included the need for plate-cage overlap in 7 stifles (26.92%) and screw head fracture in 1 (3.85%). Post-operative complications included tibial tuberosity fracture (3.85%), post-operative medial patella luxation (7.69%), and persistent lameness (7.69%). Of the 26 stifles evaluated in the medium term (>6-12 months) post-operatively, 92.3% had no lameness, with the remaining 7.7% having Grade 1 lameness. A good to excellent clinical outcome was noted in all 26 stifles that underwent TTA with novel mini plates.

Comparison of Two Preoperative Radiographic Methods for Assessing Tibial Tuberosity Advancement to Achieve a Postoperative Patella Tendon Angle of 90° in Dogs.

Previous studies have suggested that the preoperative methods used to plan tibial tuberosity advancement in dogs may result in under-advancement. Therefore, this cadaveric study compared the effectiveness of the common tangent method and the tibial-anatomy-based method for achieving a target patellar tendon angle (PTA) of 90° after the modified Maquet procedure. Twenty stifle joints of mesomorphic dogs were randomly assigned to the two measurement methods. Radiographs taken in the mediolateral projection were used to measure tibial tuberosity advancement, and the wedge size was selected accordingly. For each surgical procedure, a custom-made three-dimensional wedge matched to an OrthoFoam wedge was used as a spacer. Postoperative radiographs were used to measure the PTA and to evaluate the position of the wedge. The measured advancement was not significantly different between the two methods. For 60% of the cases, the advancement measured using the common tangent method was <5.3 mm and the wedge size was increased to match that of commercially available wedges. Consequently, there was a significant difference between the measurements and wedges selected between the two procedures. The postoperative PTA did not differ significantly between the two methods and was 90° ± 5° in 80% of the stifles. The position of the wedge relative to the osteotomy was not significantly different between the methods. In conclusion, the advancement determined using the tibial-anatomy-based method was generally consistent with the size of commercially available wedges, and the method yielded a mean postoperative PTA of 90°.

Long-term outcome in dogs with cranial cruciate ligament disease evaluated using the canine orthopaedic index.

Cranial cruciate ligament disease (CCLD) is common in dogs, but studies on the long-term treatment outcome are scarce. The long-term outcome in a cohort of 71 dogs with CCLD treated with tibial plateau levelling osteotomy (TPLO, n = 18), tibial tuberosity advancement (TTA, n = 23) or lateral fabellotibial suture (LFS, n = 30) was evaluated using the canine orthopaedic index. The risk of stiffness and lameness was increased in dogs treated with TPLO (stiffness: incidence rate ratio [IRR] 1.33, p = 0.015; lameness: IRR 1.34, p = 0.020) or TTA (stiffness: IRR 1.26, p = 0.035; lameness: IRR 1.31, p = 0.026) when compared to LFS at a median follow-up time of 4.6 years. No follow-up veterinary examination was performed. Data were collected from only two university animal hospitals, and thus, a referral bias towards more complicated cases is possible, which may limit the generalisability of the results. Clinicians can use the results to inform dog owners about the expected long-term outcome in dogs with CCLD.

Meniscal Load and Load Distribution in the Canine Stifle after Modified Tibial Tuberosity Advancement with 9 mm and 12 mm Cranialization of the Tibial Tuberosity in Different Standing Angles.

The aim of this study was to investigate the kinetic and kinematic changes in the stifle after a modified tibial tuberosity advancement (TTA) with 9 and 12 mm cranialization of the tibial tuberosity in different standing angles. Biomechanical ex vivo study using seven unpaired canine cadaver hindlimbs. Sham TTA surgery was performed. Motion sensors were fixed to the tibia and the femur for kinematic data acquisition. Pressure mapping sensors were placed between femur and both menisci. Thirty percent body weight was applied to the limbs with the stifle in 135 or 145 degrees of extension. Each knee was tested in 135 degrees with intact cranial cruciate ligament (CCL) and deficient CCL with 12 mm cranialization of the tibial tuberosity in 135 and 145 degrees of extension. The last two tests were repeated with 9 mm. Transection of the CCL altered kinematics and kinetics. Tibial tuberosity advancement with 12 mm cranialization sufficiently restored stifle kinematics in 135 and 145 degrees but 9 mm TTA failed to do so in 135 degrees. The same effects were seen for internal rotation of the tibia. After TTA, a significant reduction in the force acting on both menisci was detected. Tibial tuberosity advancement could restore stifle kinematics and meniscal kinetics after transection of the CCL ex vivo in the present study. Tibial tuberosity advancement reduced the contact force ratio on both menisci significantly. No changes of peak pressure and peak pressure location occurred following TTA under any of the tested experimental settings. Increased stifle extension (145 degrees) might lead to more stability, contradictory to biomechanical theory.

Economic Considerations on Costs and Pricing of Two Surgical Techniques for Treating Cranial Cruciate Disease in Dogs.

In surgical treatment of cranial cruciate ligament disease in dogs, Tibial Plateau Levelling Osteotomy (TPLO) and Tibial Tuberosity Advancement (TTA) are commonly established procedures and have proven effective in restoring limb function. Unlike clinical outcome, economic aspects have not been studied as extensively. However, the surgical intervention poses an enormous financial burden on patients' owners. In a veterinary practice setting, this study compares prices for TPLO and TTA and examines prices differences as well as potential cost drivers. Charges for veterinary treatments are based on the Gebührenordnung für Tierärztinnen und Tierärzte (GOT), which is mandatory for veterinarians in Germany but allows a certain range in billing. This study found that TPLO is charged at a higher price than TTA; however, this might not cover the additional costs of this procedure. The price is also associated with weight, heavier dogs being more expensive. The underlying strategies for pricing decisions may be based on costs, as efforts for TPLO and heavier dogs are higher in terms of a prolonged surgical time, the number of staff involved and in surgeons' training. Price setting may also be based on a quality promise, suggesting better clinical outcome in a more expensive procedure. Future investigations should involve economic considerations and consider cost-effectiveness analysis when evaluating surgical treatment options.

BE A SOFTY: ENHANCED BONE FORMATION IN OPTIMIZED, LOW-STIFFNESS 3D-PRINTED TITANIUM IMPLANTS. AN IN VIVO TIBIAL OSTEOTOMY STUDY

Introduction: The mechanobiology and response of bone formation to strain under physiological loading is well established, however investigation into exceedingly soft scaffolds relative to cancellous bone is limited. In this study we designed and 3D printed mechanically-optimised low-stiffness implants, targeting specific strain ranges inducing bone formation and assessed their biological performance in a pre-clinical in vivo load-bearing tibial tuberosity advancement (TTA) model. The TTA model provides an attractive pre-clinical framework to investigate implant osseointegration within an uneven loading environment due to the dominating patellar tendon force.A knee finite element model from ovine CT data was developed to determine physiological target strains from simulated TTA surgery. We 3D printed low-stiffness Ti wedge osteotomy implants with homogeneous stiffness of 0.8 GPa (Ti1), 0.6 GPa (Ti2) and a locally-optimised design with a 0.3 GPa cortex and soft 0.1 GPa core (Ti3), for implantation in a 12-week ovine tibial advancement osteotomy (9mm). We quantitatively assessed bone fusion, bone area, mineral apposition rate and bone formation rate.Optimised Ti3 implants exhibited evenly high strains throughout, despite uneven wedge osteotomy loading. We demonstrated that higher strains above 3.75%, led to greater bone formation. Histomorphometry showed uniform bone ingrowthin optimised Ti3 compared to homogeneous designs (Ti1 and Ti2), and greater bone-implant contact. The greatest bone formation scores were seen in Ti3, followed by Ti2 and Ti1.Results from our study indicate lower stiffness and higher strain ranges than normally achieved in Ti scaffolds stimulate early bone formation. By accounting for loading environments through rational design, implants can be optimised to improve uniform osseointegration. Design and 3D printing of exceedingly soft titanium orthopaedic implants enhance strain induced bone formation and have significant importance in future implant design for knee, hip arthroplasty and treatment of large load-bearing bone defects.

Computer-Aided Ankle Ligament Injury Diagnosis from Magnetic Resonance Images Using Machine Learning Techniques.

Ankle injuries caused by the Anterior Talofibular Ligament (ATFL) are the most common type of injury. Thus, finding new ways to analyze these injuries through novel technologies is critical for assisting medical diagnosis and, as a result, reducing the subjectivity of this process. As a result, the purpose of this study is to compare the ability of specialists to diagnose lateral tibial tuberosity advancement (LTTA) injury using computer vision analysis on magnetic resonance imaging (MRI). The experiments were carried out on a database obtained from the Vue PACS-Carestream software, which contained 132 images of ATFL and normal (healthy) ankles. Because there were only a few images, image augmentation techniques was used to increase the number of images in the database. Following that, various feature extraction algorithms (GLCM, LBP, and HU invariant moments) and classifiers such as Multi-Layer Perceptron (MLP), Support Vector Machine (SVM), k-Nearest Neighbors (kNN), and Random Forest (RF) were used. Based on the results from this analysis, for cases that lack clear morphologies, the method delivers a hit rate of 85.03% with an increase of 22% over the human expert-based analysis.

One-Stage Revision with Cage Replacement as Treatment for Refractory Infections after Tibial Tuberosity Advancement in 7 Dogs

AbstractThe aim of this article was to report surgical and medical management, and to evaluate complications and outcome of dogs treated for refractory infection after tibial tuberosity advancement (TTA) with a one-stage revision surgery consisting of implant removal and replacement of a TTA cage. It was a retrospective case series. Seven cases were included in this study. Loss of advancement of the tibial tuberosity or tibial crest fractures did not occur in any case. One-stage revision surgery was successful in 5/7 cases (71%) with good long-term outcomes. Persistent infection resulted in removal of the replaced new cage in 2/7 cases (29%), of which one was associated with septic arthritis caused by multi-resistant bacteria. One-stage revision with immediate replacement of a new TTA cage successfully prevented loss of advancement of the tibial tuberosity and tibial crest fractures in this short case series. Further studies investigating possible improvements in the treatment protocol for refractory infection after TTA are warranted.

Enhanced bone formation in locally-optimised, low-stiffness additive manufactured titanium implants: An in silico and in vivo tibial advancement study.

A tibial tuberosity advancement (TTA), used to treat lameness in the canine stifle, provides a framework to investigate implant performance within an uneven loading environment due to the dominating patellar tendon. The purpose of this study was to reassess how we design orthopaedic implants in a load-bearing model to investigate potential for improved osseointegration capacity of fully-scaffolded mechanically-matched additive manufactured (AM) implants. While the mechanobiological nature of bone is well known, we have identified a lower limit in the literature where investigation into exceedingly soft scaffolds relative to trabecular bone ceases due to the trade-off in mechanical strength. We developed a finite element model of the sheep stifle to assess the stresses and strains of homogeneous and locally-optimised TTA implant designs. Using additive manufacturing, we printed three different low-stiffness Ti-6Al-4V TTA implants: 0.8GPa (Ti1), 0.6GPa (Ti2) and an optimised design with a 0.3GPa cortex and 0.1GPa centre (Ti3), for implantation in a 12-week in vivo ovine pilot study. Static histomorphometry demonstrated uniform bone ingrowth in optimised low-modulus Ti3 samples compared to homogeneous designs (Ti1 and Ti2), and greater bone-implant contact. Mineralising surfaces were apparent in all implants, though mineral apposition rate was only consistent throughout Ti3. The greatest bone formation scores were seen in Ti3, followed by Ti2 and Ti1. Results from our study suggest lower stiffnesses and higher strain ranges improve early bone formation, and that by accounting for loading environments through rational design, implants can be optimised to improve uniform osseointegration. STATEMENT OF SIGNIFICANCE: The effect of different strain ranges on bone healing has been traditionally investigated and characterised through computational models, with much of the literature suggesting higher strain ranges being favourable. However, little has been done to incorporate strain-optimisation into porous orthopaedic implants due to the trade-off in mechanical strength required to induce these microenvironments. In this study, we used finite element analysis to optimise the design of additive manufactured (AM) titanium orthopaedic implants for different strain ranges, using a clinically-relevant surgical model. Our research suggests that there is potential for locally-optimised AM scaffolds in the use of orthopaedic devices to induce higher strains, which in turn encourages de novo bone formation and uniform osseointegration.

Comparison of the short-term complications of TTA-rapid and modified cTTA procedures.

The objective of this retrospective study was to determine the complications of the first 30 tibial tuberosity advancement rapid (TTA-rapid) and 30 modified circular tibial tuberosity advancement (mcTTA) procedures performed by our team, and to compare the results with the findings reported in the literature. Our research was based on 30 procedures in each group. All dogs were client-owned. Data were collected only for the study of cases that had a minimum follow-up period of 3 months. Intraoperative (IO) and postoperative (PO) complications were assessed, with the latter divided into two subgroups: major and minor. Results obtained for the TTA-rapid group: IO complications 23.3% (7/30), major PO complications 13.3% (4/30), minor PO complications 16.7% (5/30). Results of the mcTTA group: IO complications 0% (0/30), major PO complications 3.3% (1/30), minor PO complications 20% (6/30). Comparing the complication rates, we found that there was a significant difference between the two groups in the occurrence of IO complications (P = 0.01054); however, there was no significant difference in the incidence of major (P = 0.3533) and minor (P > 0.9999) PO complications between groups. Our results are consistent with the findings reported in the literature and suggest that both techniques are efficient and carry a relatively low complication rate.

Determination of the Stifle Angle at Standing Position in Dogs.

The cranial cruciate ligament rupture is one of the most common orthopaedic diseases encountered in dogs. Surgical techniques have been developed to stabilize the stifle, with an overall accepted benefit of tibial osteotomies among which is the tibial tuberosity advancement (TTA). Prior to surgery, the required TTA must be determined on a strict lateral radiographical view of the affected stifle with femur and tibia at an angle of 135° as initially recommended. This value, initially determined in only two dog breeds, has been considered the mean standard value of the canine stifle angle during the mid-stance phase. We sought to determine if this particular stifle angle around mid-stance phase was similar among multiple dog breeds. We built up a custom-made radiographic system for stifle angle measurement in standing dogs. A mean value of stifle angle of 145° was obtained. Mean stifle angle at mid-stance phase in a healthy dog is regularly higher than 135° and is likely breed and individual dependent. The pre-operative measurement of the required TTA made on stifles in 145° extension, a value close to full physiological extension could contribute to decreasing the incidence of late post-operative meniscal lesion, consecutive to underestimation of TTA.

Biomechanical testing of canine tibiae: Changes resulting from different tibial tuberosity advancement techniques - Pilot study.

The objective of the present pilot study was to determine the force required to break (a) intact canine tibiae, (b) tibiae following the osteotomy of the tibial tuberosity and (c) tibiae following Tibial Tuberosity Advancement- (TTA-) rapid surgery. Six pairs of tibiae of dogs between 15 and 35 kg body weight were used in a cadaver study. Three groups were created with four tibiae in each group; intact (Group 1), osteotomy of the tibial tuberosity and tibial crest (Group 2) and TTA-rapid (Group 3). The tibiae were put under static axial compressive load, applied until failure. The force required to break the tibiae was termed maximal force (F max). The mean of F max was 8193.25 ± 2082.84 N in Group 1, 6868.58 ± 1950.44 N in Group 2 and 7169.71 ± 4450.39 N in Group 3. The sample size was small for a statistical analysis but as a preliminary result, we have determined the force (F max) required to break canine tibiae. Furthermore, we hypothesise that osteotomies result in weakening of the tibial structure.

Tibial Tuberosity Advancement Techniques (TTAT): A Systematic Review.

Simple SummaryThe aim of this manuscript is to report and critically review the currently available literature about so-called “new generation Tibial Tuberosity Advancement Techniques”. According to PRISMA guidelines, the authors investigated and reported data about preoperative planning, surgical procedure, outcome, and complications of these different techniques. The main problems addressed were the lack of prospective studies with a large study population and univocal data collection about preoperative planning and outcome.(1) Background: Several surgical techniques were described for the treatment of cranial cruciate ligament rupture in dogs. This report aims to critically review the available literature focused on preoperative planning, surgical procedure, follow-up, and complications of cranial cruciate ligament rupture treated by tibial tuberosity advancement techniques; (2) Methods: three bibliographic databases: PubMed, Google Scholar, and Scopus were used for a board search of TTAT (canine OR dog). Five GRADE recommendations according to Grading of Recommendations Assessment, Development and Evaluation and Joanna Briggs Institute Critical Appraisal Checklists were applied to the studies included. Data regarding preoperative planning (a measure of advancement), meniscal disease (meniscectomy, meniscal release, and late meniscal tears), and postoperative patellar tendon angle were recorded. Time frame, outcome, and complications were classified according to Cook’s guidelines; (3) Results: from 471 reports yielded, only 30 met the inclusion criteria. The common tangent method was the most commonly reported measurement technique for preoperative planning. The 40.21% of stifles presented meniscal tears at surgery, while 4.28% suffered late meniscal tears. In short-, mid-and long-term follow-ups examined showed a full/acceptable function was shown in >90% of cases. Among all new generation techniques, minor complications were reported in 33.5% of cases and major complications in 10.67%; (4) Conclusions: Compared to traditional TTA, new generation TTAT resulted effective in the treatment of cranial cruciate ligament failure, showing a lower rate of late meniscal injury but a higher rate of minor complications.

Mechanical Testing of the New Cage for Tibial Tuberosity Advancement with the Cranial Implant Fixation (TTA CF) Technique-Ex Vivo Study on Sheep Model.

Simple SummaryTibial tuberosity advancement is a method of surgical treatment of cranial cruciate ligament rupture in animals.. In previous reports, the biomechanical effectiveness of tibial tuberosity advancement surgeries was evaluated by axial pressure on the tibial tuberosity to test the strength and resistance of the fixation or by pulling on the tuberosity. To our knowledge, there are no reports that examined the strength that is needed to pull out an implant from the tibia after tibial advancement. This study is the first report that focuses on pulling out the TTA implant, which corresponds to the biointegrity and ingrowth of the TTA cage with the tibia.Background: Modifications of tibial tuberosity advancement are well accepted for cranial cruciate rupture repair. We compared the loads that were needed to pull the TTA CF cage out in the two groups. The first group consisted of five sheep in which osteotomy and TTA CF cage fixation were performed as assumed preoperatively. The second group consisted of five sheep in which intraoperative or postoperative discrepancies from preoperative planning were found. This is also the first report describing biomechanical testing after tibial tuberosity advancement with cranial implant fixation (TTA CF) surgical procedures. Results: A total of 10 ovine proximal tibiae were tested biomechanically by tearing out TTA CF implants from the bone. The mean maximal loaded forces to pull out the cage in Group 1, in which fixation of the implant was performed as assumed preoperatively, was 878 ± 61 N, and in Group 2, in which discrepancies from preoperative planning were found, was 330 ± 55 N. The mean implant displacement under maximal load to failure was 2.6 mm and 2.2 mm in Groups 1 and 2, respectively. There was a significant difference between Group 1 and Group 2 in the maximal loads-to-failure; however, the difference in the displacement at maximal loaded forces to pull out the cage was not significant between the groups. Conclusions: The mean maximal loaded forces to pull out the cage was significantly lower in Group 2, where discrepancies from preoperative planning were found (878 ± 61 N vs. 330 ± 55 N). The lower forces that were needed to extract the TTA CF implant from the tibia can lead to the conclusion that biointegration of the implant is also weaker. Correct positioning of the osteotomy line and TTA CF implant is essential for good biointegrity and thus for limiting complications in the form of tibial tuberosity avulsion fracture or tibial shaft fracture.

The Effect of Increasing Tibial Tuberosity Advancement and Quadriceps Muscle Force on Cranial Translation of the Tibia in the Cranial Cruciate Deficient Stifle Joint in Dogs.

BackgroundCranial cruciate ligament (CCL) disease is a well-known pathology that generates both rotational and translational instability of the stifle joint that leads to osteoarthritis in dogs. Tibial tuberosity advancement (TTA) is a common surgical technique used to dynamically neutralize the tibiofemoral shear forces to achieve stifle joint stability. However, significant persistent instability has been documented in clinical cases. The purpose of this study was to evaluate the effect of increasing quadriceps load, increasing tibial tuberosity advancement, and increasing joint flexion angle on the cranial translation of the tibia relative to the femur in the cranial cruciate ligament deficient stifle joint.Methods and ResultsSix cadaveric hind limbs were collected from six healthy mixed breed dogs of medium build and prepared for biomechanical testing. The specimen was placed into a custom-made joint testing machine, and translation of the tibia relative to the femur was measured at stifle angles of 135°, 120°, and 105°. Cranial tibial thrust was generated by applying a vertical load to the metatarsal pad and the quadriceps muscle was simulated with loads of 0, 5, and 10 kg applied to the patella via a system of weights and pulleys. All specimens were tested with the CCL intact and cut, both of which served as controls. The tibial tuberosity was then advanced using both 6 mm and 9 mm cages, and the specimen was tested using the identical technique. Each specimen was loaded to failure by increasing the load applied to the pes until the sudden marked cranial translation of the tibia. Tibial tuberosity advancement with an applied quadriceps load was successful in limiting cranial tibial translation in 54/62 tests. Under similar loading conditions, TTA failed to limit cranial translation in 8 tests. The failures occurred at all angles of flexion examined. In the cases that failed cranial translation could be limited by either increasing the quadriceps load or increasing the amount of tibial tuberosity advancement.ConclusionThis study showed that TTA with an applied quadriceps load is effective at decreasing cranial tibial translation at functional joint angles.

Comparison of four methods to -determine cage width in tibial tuberosity advancement.

The objective of this study was to test a method for determining the width of the tibial tuberosity advancement (TTA) cage without the need for extension of the stifle joint, while producing preoperative radiographs. TTA cage size was determined by applying 4 different methods using radiograph images in mediolateral direction of fully extended stifles of dogs (n=43), with and without naturally occurring cranial cruciate ligament disease: parallel shift (PS) method, common tangent (CT) method, «2,1» method (cage size = 2,1 × tibia plateau length - tibial tuberosity width), and margo cranialis (MC) method (cage size = length of MC/6*1,75). Two new methods, «2,1», and MC were compared to the existing CT and PS methods. All 4 methods resulted in reliable cage sizes. Intraclass correlation coefficients showed an excellent reliability of the CT and PS to the «2,1» method and a good reliability in regards to the MC method. In conclusion, TTA cage size of the tibia anatomy alone can be determined on radiographs without the need of full extension of the stifle joint. Based on the results, two different methods of cage size measurement are recommended in order to increase diagnostic accuracy and to prevent the insertion of suboptimal cages.