Canine Stifle Research Articles

Proximal lateral insertion portal of an intra-articular arthroscopic stifle lever: A cadaveric study.

To (1) Describe the proximal lateral insertion portal for the placement of an intra-articular distraction lever. (2) Assess for associated damage with the insertion of the lever and (3) evaluate the impact of duration of lever use on articular cartilage damage. Ex vivo canine cadaveric experimental study. Paired canine stifles from seven cadavers (14 stifles from dogs weighing >20 kg). A separate 0.5 cm proximal lateral portal was established adjacent to the lateral scope portal. A standard Ventura stifle thrust lever (VSTL) was inserted without removing the arthroscope. In Group A, the VSTL was placed in distraction for 5 min while in Group B the VSTL was placed for 10 min. The stifle joints were disarticulated and evaluated for associated damage to the long digital extensor tendon and iatrogenic articular cartilage injury (IACI) via India ink assay. No damage to the long digital extensor tendon was noted in any of the specimens during dissection. Superficial IACI was present in all specimens. There were no differences between groups when assessing for overall IACI. A proximal lateral portal and insertion of a standard VSTL can be performed without removing the arthroscope. The use of a proximal lateral lever portal without repositioning the arthroscope was repeatable without damaging the long digital extensor tendon. A duration of up to 10 min in which the thrust lever was engaged did not result in increased visual cartilage damage.

Evaluation of Meniscal Load and Load Distribution in the Sound Canine Stifle at Different Angles of Flexion.

The aim of the study was to investigate the contact mechanics and kinematic changes in the stifle in different standing angles. We performed a biomechanical ex vivo study using pairs of canine cadaver hindlimbs. Motion sensors were fixed to the tibia and the femur for kinematic data acquisition. Pressure mapping sensors were placed between the femur and both menisci. Thirty percent bodyweight was applied to the limbs with the stifle in 125, 135, or 145 degrees of extension. Stifle flexion angle influences femoromeniscal contact mechanics significantly. The load on both menisci was significantly higher for 125 and 135 degrees in comparison to 145 degrees. Additionally, the center of force was located significantly more caudal when comparing 125 to 145 degrees in the medial meniscus as well as in both menisci combined. The angle of knee flexion significantly impacts the contact mechanics between the femur and the meniscus. As the knee flexes, the load on both menisci increases.

Estimation of footprints of the canine stifle ligaments using deformable shape templates of bones

Knowledge regarding the ligament footprints in the canine stifle is essential for biomechanical modeling of the joint and patient-specific surgical planning for anatomical ligament reconstruction. The present study aimed to establish and evaluate deformable shape templates (DSTs) of the femur and tibia with footprints of the cruciate and collateral ligaments embedded for the noninvasive estimation of ligament footprint positions. To this end, a data set of computed tomography (CT)-derived surface models of the femur and tibia were established and used to build statistical shape models (SSMs). The contours of the stifle ligaments were obtained from CT scans of 27 hindlimb specimens with radio-opaque markings on the ligament footprints. The DST, constructed by embedding averaged footprint contours into the SSM, was used to estimate subject-specific ligament footprints in a leave-one-out cross-validation framework. The DST predictions were compared with those derived from radio-opaque-marked footprints. The results showed that the averaged Euclidean distances between the estimated and reference footprint centroids were less than 1.2 mm for the cruciate ligaments and 2.0 mm for the collateral ligaments. The DST appeared to provide a feasible alternative approach for noninvasively estimating the footprints of the stifle ligaments in vivo.

Biomechanical effects of cranial closing wedge osteotomy on joint stability in normal canine stifles: an ex vivo study.

Cranial closing wedge osteotomy (CCWO) is a functional stabilisation technique for cranial cruciate ligament (CrCL) ruptures. This biomechanical study aimed to evaluate the influence of CCWO on the stability of the stifle joint. Eighteen Beagle stifle joints were divided into two groups: control and CCWO. The stifle joints were analyzed using a six-degree-of-freedom robotic joint biomechanical testing system. The joints were subjected to 30N in the craniocaudal (CrCd) drawer and proximal compression tests and 1 Nm in the internal-external (IE) rotation test. Each test was performed with an extension position, 135°, and 120° of joint angle. The stifle joints were tested while the CrCLs were intact and then transected. In the drawer test, the CCWO procedure, CrCL transection, and stifle joint flexion increased CrCd displacement. The CCWO procedure and CrCL transection showed an interaction effect. In the compression test, the CCWO procedure decreased and CrCL transection and stifle joint flexion increased displacement. In the IE rotation test, CCWO, CrCL transection, and stifle joint flexion increased the range of motion. CCWO was expected to provide stability against compressive force but does not contribute to stability in the drawer or rotational tests. In the CCWO-treated stifle joint, instability during the drawer test worsened with CrCL transection. In other words, performing the CCWO procedure when the CrCL function is present is desirable for stabilizing the stifle joint.

Ultrashort Echo Time Quantitative Magnetic Resonance Imaging of the Cruciate Ligaments in Normal Beagles.

The aim of this study was to provide normative ultrashort echo time magnetic resonance imaging (UTE MRI) data of the patellar ligament (PL), cranial cruciate ligament (CrCL) and caudal cruciate ligament (CdCL) in non-lame Beagles. Eight stifles from four subjects obtained immediately postmortem were imaged using UTE MRI in the true sagittal plane. Regions of interest were drawn manually and the total (T2*), short T2* (T2*S) and long T2* (T2*L) values of the signal decay were calculated to evaluate the bound and free water components of the tendon. The T2*S, T2*L and T2* values were compared between the PL, CrCL and CdCL RESULTS: The mean and standard deviation of T2*S, T2*L and T2* were as follows: 0.54 ± 0.13, 4.65 ± 1.08 and 8.35 ± 0.82 ms for the PL; 0.46 ± 0.14, 5.99 ± 0.52 and 8.88 ± 0.4 ms for the CrCL and 0.41 ± 0.13, 7.06 ± 0.57 and 9.26 ± 0.18 ms for the CdCL. Significant differences were found between the T2*L component of the PL and each CrCL/CdCL and a smaller difference was noted between the T2*L of the CrCL and CdCL (p = 0.05). No difference of the T2*S value was found between any of the ligaments. Establishing normative UTE data of the canine stifle is valuable for comparison in future studies in which normal and damaged ligaments may be evaluated, particularly in those affected limbs in which no instability is identified on physical examination in which normal and damaged ligaments may be evaluated.

Effect of center of rotation of angulation-based levelling osteotomy on instantaneous center of rotation ex vivo

Cranial cruciate ligament rupture is a common cause of femorotibial instability in dogs. Despite numerous techniques being described for achieving joint stabilization, no consensus exists on the optimal management strategy. This ex vivo study utilized the path of the instantaneous center of rotation (ICR) to compare normal, pathological and treated joints. Fluoroscopic recordings of seven limbs from a previous study of canine stifle joint stability following center of rotation of angulation-based levelling osteotomy (CBLO) with and without hamstring loading were analyzed using least-squares approximation of the ICR and estimation of percentage gliding (vs. rolling) to determine if alterations in ICR path and gliding caused by CCL transection and following meniscal release could be normalized by CBLO. In intact joints, the ICR path was located mid-condyle, but this shifted significantly proximally and caudally following CCL transection and medial meniscal release (p < 0.007, p < 0.04). Hamstring loading resulted in qualitative and some quantitative improvements in joint movement based on percentage gliding movement analysis. The ICR path after CBLO remained significantly different to the intact location with or without a hamstring load (p < 0.02, p < 0.04), potentially consistent with CBLO aims of mild residual instability. CBLO resulted in percentage gliding characteristics not significantly different to intact joints (p > 0.08). Qualitative improvements in ICR path and percentage gliding quantities and variability suggest that hamstring loading positively influences joint biomechanics and that further investigation of this role ex vivo and clinically is warranted.

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.

The Effect of Therapeutic Exercise on Body Weight Distribution, Balance, and Stifle Function in Dogs following Stifle Injury.

Stifle injury is common in the companion dog population, affecting weight bearing, neuromuscular control, and balance. Therapeutic exercises after stifle injury seem to be effective, but high-quality research evaluating the effects is lacking. This randomized controlled trial evaluated the effects of a 12-week progressive therapeutic home exercise protocol on three-legged standing, targeting balance and postural- and neuromuscular control and disability in dogs with stifle injury. Thirty-three dogs with stifle injury were randomly allocated to intervention (n = 18) and control groups (n = 15), both receiving a standard rehabilitation protocol. Additionally, the intervention group received a progressive therapeutic exercise protocol. The outcome measures were static body weight distribution between hindlimbs, balance control, the canine brief pain inventory, and the Finnish canine stifle index. Both groups improved after the intervention period, but the group using the progressive therapeutic exercise protocol improved to a greater extent regarding static body weight distribution between the hindlimbs (I: median = 2.5%, IQR = 1.0-4.5; C: median = 5.5%, IQR = 3.0-8.8), pain-related functional disability (I: median = 0.0, IQR = 0.0-0.2; C: median = 0.9, IQR = 0.1-1.8), and stifle function (I: median = 25.0, IQR = 9.4-40.6; C: median = 75.0, IQR = 31.3-87.5), with intermediate to strong effects. These clinically relevant results indicate that this home exercise program can improve hindlimb function and restore neuromuscular control.

Comparative digital study of two cranial rotation methods of the proximal fragment on the center of rotation of angulation-based leveling osteotomy planning with different tibial distal anatomical axes

The center of rotation of angulation (CORA)-based leveling osteotomy (CBLO) technique was developed for cranial cruciate ligament (CrCL) rupture treatment, aiming to modify the mechanical-anatomical angle (AMA), which is described as a predictive risk factor for the disease and is recommended to be taken into consideration when one is choosing a surgical procedure for tibial plateau slope alteration. Identifying a tibial distal anatomical axis (DAA) is essential in CBLO surgical planning and measuring AMA amplitude. The aim of this study was: to evaluate two methods of cranial rotation of the proximal fragment using four different tibial distal anatomical axes for digital planning on the CBLO technique, comparing its effectiveness in achieving the desired tibial plateau angle (TPAd) and closing the AMA angle. Tibial measurements were made with the vPOP pro software using 30 mediolateral radiographs of canine stifles. The DAA described by four authors was used based on the amount of Rotation completed (Rc) for each. The rotation methods evaluated were: 1) commercial CBLO table (RT) and 2) overlapping the tip of the intercondylar eminence with the corresponding DAA line (RE). The TPAd to be obtained was fixed at 10°, and the final AMA to be achieved at 0°. The mean values and standard deviations of the final TPA and final AMA with the rotation method were TPA(RT)f(%TPAd), TPA(RE)f(%TPAd), AMA(RT)f(%AMAzero), AMA(RE)f(%AMAzero). The results of each author were Hulse 10.0 ± 0.3(46.6%), 9.9 ± 0.1(60%), 0.3 ± 0.3(33.3%), 0.3 ± 0.3(13.3%), Osmond 10.1 ± 0.2(75%), 10,1 ± 0.2(83.3%), 0.4 ± 0.4(33.3%), 0.4 ± 0.3(8,3%), Miles 10.0 ± 0.1(66.6%), 10.0 ± 0.1(75%), 0.2 ± 0.1(16.6%), 0.2 ± 0.1(8.3%), Tudury 9.6 ± 0.6(31.2%), 9.5 ± 0.2(31.2%), 1.0 ± 0.7(18.7%), 1.0 ± 0.6(12.5%), respectively. The initially described RT obtained a higher percentage of AMA at zero degrees. Therefore, the RE method is discarded for use as an alternative to CBLO planning.

Accuracy and Confidence in Performing Canine Stifle Goniometry was Similar between Simulation-Model or Traditional Textbook Trained Veterinary Students

Goniometry is an essential skill used in veterinary rehabilitation settings to monitor orthopedic conditions. Our objectives were to create a normal canine stifle goniometry model and to compare students’ confidence and accuracy in performing goniometry with exposure to either the model or traditional teaching methods. We hypothesized that students would demonstrate goniometry skills more confidently and accurately after using a simulation model than those given traditional materials. A flexible model of a canine stifle was made. Twenty-eight veterinary students (8 clinical, 20 pre-clinical) prepared with either instructional material from a textbook ( n = 15) or access to the stifle model ( n = 13), and then assessed when performing goniometry (live dog). Students completed pre- and post-surveys where they indicated their confidence and anxieties. Statistical analyses included thematic analysis, descriptive statistics, and Chi-square analyses (significant at p ≤ .05). There was no difference in goniometry assessment or anatomy palpation scores between the model and reading groups. Clinical students ( n = 8) achieved higher scores in goniometry assessment ( p = .01) and anatomy palpation ( p = .04). Students were more confident when identifying their anatomical landmarks after using prep materials as compared to before using the prep materials ( p = .03), but only averaged identification of 3/5 landmarks. Half could not correctly read the goniometer. In general learning with models was preferred by all. There was no difference in learning between the model and textbook, so either can be used based on student preference. Further goniometer instructions should be provided. Anatomy of live dogs should be assessed more frequently pre-clinically.

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

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). 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. The ECS repaired at quasi-IPs was shown to restore cranial instability of the stifles with averaged CTT magnitudes < 1.4mm. 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. 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.

Partial Parasagittal Patellectomy in Dogs: A Retrospective Case Series of 19 Dogs.

The aim of this study was to describe partial parasagittal patellectomy for the surgical management of patellar luxation, including surgical technique, proposed indications, complications, and outcomes in a cohort of dogs. This is a single-center retrospective clinical case series. Medical records (2019-2020) of dogs presenting for patellar luxation were reviewed. Clinical signs, luxation direction and grade, preoperative imaging and intraoperative findings, and complications were retrospectively retrieved. Owners were contacted via questionnaire for medium- and long-term follow-up. A total of 24 stifles in 19 dogs met the inclusion criteria. Intraoperative minor complications occurred in four stifles. A single minor complication occurred postoperatively with no major complications. Increased thickness and radiographic attenuation of the patellar ligament were noted in 14 stifles at radiographic reassessment. Re-luxation was not encountered, with long-term owner-assessed outcome as good to excellent in all cases. Partial parasagittal patellectomy, used in conjunction with block recession trochleoplasty and tibial tuberosity transposition, provided reliable resolution of patellar luxation in canine stifles with grade 2 or 3 luxation where width mismatch between the patella and the trochlea was noted intraoperatively. Long-term outcome appears to be good to excellent with a low rate of complication.

Intra-articular Pressure Changes during Stifle Arthroscopy Using a Cadaver Model

Abstract Objective The aim of the study was to measure canine stifle intra-articular pressures (IAP) during arthroscopy using three different fluid pump pressure (FPP) settings. Study Design Frozen thawed canine cadavers were used. The stifle was distended using a 2.7 mm arthroscope connected to a commercial fluid pump. Intra-articular pressure was measured using a portable pressure gauge connected to an intra-articular 18 G needle. Intra-articular pressure was recorded during stifle extension, 90 degrees flexion and full flexion at three different FPP (30, 50, 80 mm Hg). Results Testing was performed on 27 stifles. Intra-articular pressure significantly increased at higher FPP (p &lt; 0.01). At FPP 30, 50, and 80 mm Hg, the mean IAP was 51.8 (95% confidence interval [CI]: 41.3–62.2), 103.3 (95% CI: 92.8–113.7), and 175.2 mm Hg (95% CI: 164.8–185.6), respectively. At FPP 30 and 50 mm Hg, IAP always remained under 170 mm Hg. At 80 mm Hg, IAP raised to or above 170 mm Hg in 11/14 stifles. Stifle position significantly affected IAP (p &lt; 0.01). Changing stifle position from 90 degrees flexion to extension significantly decreased IAP by 22.4 mm Hg (95% CI: 16.2–28.5), and changing to full flexion significantly increased IAP by 20.9 mm Hg (95% CI: 14.8–27.1; p &lt; 0.01). Conclusion Our results suggest that caution should be used during stifle arthroscopy to limit risk for iatrogenic capsular damage. Fluid pump pressure 30 mm Hg is considered safe when using a 2.7 mm arthroscope and high flow cannula. If higher FPP is necessary for visualization, duration of stifle flexion should be limited. Fluid pump pressure 80 mm Hg should be avoided.

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.

Evaluation of the accuracy and intra- and interobserver reliability of three manual laxity tests for canine cranial cruciate ligament rupture-An ex vivo kinetic and kinematic study.

To investigate the accuracy and intra- and interobserver reliability of the cranial drawer test (CD), tibial compression test (TCT), and the new tibial pivot compression test (TPCT) in an experimental setting resembling acute cranial cruciate ligament rupture (CCLR) and to elucidate the ability to subjectively estimate cranial tibial translation (CTT) during testing. Experimental ex vivo study. Ten cadaveric hindlimbs of large dogs. Kinetic and 3D-kinematic data was collected while three observers performed the tests on each specimen with intact (INTACT) and transected cranial cruciate ligament (CCLD) and compared using three-way repeated-measures ANOVA. Subjectively estimated CTT (SCTT), obtained during a separate round of testing, was compared to kinematic data by Pearson correlation. CTT was significantly higher for CCLD than for INTACT for all tests, resulting in 100% sensitivity and specificity. TPCT induced the highest CTT and internal rotation. Intra- and interobserver agreement of translation was excellent. For rotation and kinetics, agreement was more variable. SCTT strongly correlated with the objectively measured values. The CD, TCT and the new TPCT were all accurate and reliable. The high translations and rotations during TPCT are promising, encouraging further development of this test. SCTT was reliable in our experimental setting. Veterinary manual laxity tests are accurate and reliable in acute CCLR. The TPCT might have potential for the assessment of subtle and rotational canine stifle instabilities. The high reliability of SCTT implies that grading schemes for stifle laxity, similar to human medicine, could be developed.

Comparison of Digital Radiography, Computed Tomography, and Magnetic Resonance Imaging Features in Canine Spontaneous Degenerative Stifle Joint Osteoarthritis

Canine stifle joint osteoarthritis (OA) is characterized by damage and degeneration of the articular cartilage and subchondral bone, bony hypertrophy at the margins, and synovial joint membrane changes. Non-invasive imaging modalities, such as digital radiography (DR), computed tomography (CT), and magnetic resonance imaging (MRI), can be used to describe these changes. However, the value of MRI in diagnosing spontaneous canine OA and the comparison of different imaging modalities have seldom been addressed. This study compared multiple noninvasive imaging modalities in canine spontaneous stifle OA cases. Four client-owned dogs with five spontaneously affected OA stifle joints were recruited and underwent DR, CT, and MRI. Information on osteophytes/enthesophytes, ligament/tendon lesions, synovial effusion and membrane thickening, subchondral bone lesions, and meniscal and cartilage lesions were scored and compared. The results showed that MRI provides the most comprehensive and superior lesion detection sensitivity for ligament, meniscus, cartilage, and synovial effusions. DR provides adequate bony structure information, while CT provides the most delicate images of bony structure lesions. These imaging findings may provide further understanding of the disease and help clinicians draft a more precise treatment plan.

Histological Findings and T2 Relaxation Time in Canine Menisci of Elderly Dogs—An Ex Vivo Study in Stifle Joints

Osteoarthritis is a chronic disease that often affects the canine stifle joint. Due to their biomechanical function, the menisci in the canine stifle play an important role in osteoarthritis. They compensate for the incongruence in the joint and distribute and minimize compressive loads, protecting the hyaline articular cartilage from damage. Meniscal degeneration favors the development and progression of stifle joint osteoarthritis. Qualitative magnetic resonance imaging (MRI) is the current golden standard for detecting meniscal changes, but it has limitations in detecting early signs of meniscal degeneration. A quantitative MRI offers new options for detecting early structural changes. T2 mapping can especially visualize structural changes such as altered collagen structures and water content, as well as deviations in proteoglycan content. This study evaluated T2 mapping and performed a histological scoring of menisci in elderly dogs that had no or only low radiographic osteoarthritis grades. A total of 16 stifles from 8 older dogs of different sex and breed underwent ex vivo magnet resonance imaging, including a T2 mapping pulse sequence with multiple echoes. A histological analysis of corresponding menisci was performed using a modified scoring system. The mean T2 relaxation time was 18.2 ms and the mean histological score was 4.25. Descriptive statistics did not reveal a correlation between T2 relaxation time and histological score. Ex vivo T2 mapping of canine menisci did not demonstrate histological changes, suggesting that early meniscal degeneration can be present in the absence of radiological signs of osteoarthritis, including no significant changes in T2 relaxation time.

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.

脛骨高平部水平化骨切り術実施後の脛骨前方引き出し兆候に関する検討

Although it is considered that tibial cranial drawer signs (TCDS) do not disappear with tibial plateau leveling osteotomy (TPLO), in some cases, this may occur and is presumed to be due to periarticular fibrosis; however to our knowledge, no reports have confirmed the disappearance of TCDS after TPLO. Here, we aimed to identify factors influencing the presence/absence of TCDS after TPLO. Thirty-five canine stifle joints requiring TPLO for cranial cruciate ligament rupture were assessed preoperatively, immediately postoperatively, and each month for 3 months following surgery. The cases were classified as those in which TCDS disappeared (13 stifles, disappeared group) and those in which TCDS remained (22 stifles, residual group). The osteoarthritis (OA) score at each postoperative time point was subtracted from the preoperative OA score (variation in OA score). There were no differences between the two groups, except in the preoperative OA scores (which were higher in the disappeared group). Significant increases in the variations in OA score were observed over time in both groups; these variations were significantly higher in the disappeared than in the residual group at 1, 2, and 3 months postoperatively. Disappearance of TCDS after TPLO is associated with a higher degree of OA progression, suggesting involvement of OA progression factors and periarticular fibrosis.

Impacts of tibial plateau levelling osteotomy on the tibial insertion of the medial collateral ligament of the canine stifle joint – A cadaveric study

ObjectiveThe aim of this study was to assess the potential consequences of tibial plateau levelling osteotomy (TPLO) for the medial collateral ligament (MCL) tibial insertion (TI) with a particular focus on the effects of the TPLO planning technique and of the size of saw blade. Study designEighty-six stifle joints were collected from 43 canine cadavers and dissected free of soft tissue to expose the MCL. The MCL insertion sites were first identified with Chinese ink on intact stifle joints, and then marked with radio-opaque barium sulfate after removal of the MCL. Mediolateral radiographs were made of each marked stifle joint and used for TPLO digital planning. For each stifle, planning the TPLO was performed by centring the osteotomy at the intersection of the tibial plateau and the mechanical axis of the tibia in group 1, and at the top of the intercondylar tubercles in group 2. Whenever possible, two saw blade sizes were tested in each group. Measurements were taken after TPLO simulation to assess how the procedure would alter the MCL TI. ResultsIn group 1, the integrity of the MCL TI was affected by the TPLO planning in 87.2% of the cases with the small saw blade and in 59.3% of the cases with the large blade, and in group 2, in 94.2% of the cases with the small and 77.9% with the large saw blade. In group 1, the osteotomy line was located above the TI, completely severing the MCL in four cases versus in 11 cases in group 2, while severing occurred in 14/15 cases with the small saw blade. ConclusionDuring TPLO, the osteotomy line transected the MCL TI in the majority of dogs. Centring the osteotomy at the intersection of the tibial plateau and the mechanical axis of the tibia and using the largest saw size that preserves tibial tuberosity and patellar tendon insertion seems to be the best way to preserve the MCL TI as much as possible. Further research is needed to evaluate the clinical impact of MCL TI transection.