Anterior cruciate ligament zoobiquity: Can man's best friend tell us we are being too cautious with the implementation of osteotomy to correct posterior tibial slope

Anterior cruciate ligament (ACL) reconstruction (ACLR) is used to treat clinical instability post ACL rupture, however, there is a high rate of incomplete return to sport and rerupture. There is increasing interest in posterior tibial slope as an intrinsic risk factor for ACLR failure and persistent instability. Zoobiquity describes the collaboration between the human and veterinary professions in order to advance the scientific understanding of both fields. Given the cranial cruciate ligament (CCL) in dogs is synonymous with the anterior cruciate ligament in humans, functioning to control internal rotation and anterior translation, but osteotomies, rather than ligament reconstruction, are the mainstay of treatment for CCL rupture, this editorial sort to gain insights into this form of treatment from the veterinary world. Level of Evidence: Level V, evidence.

Objective and owner-reported outcomes after modified cranial closing wedge ostectomy: a case series

Immediate and longer-term outcomes of a cranial closing wedge ostectomy variant for management of canine cranial cruciate ligament disease were assessed in this single-center retrospective consecutive study. Records and radiographs were retrieved and assessed by three independent observers to evaluate tibial plateau angle, anatomical-mechanical axis angle, tibial tuberosity distalization, and mechanical axis length before and after surgery. Kinetic gait analysis and owner questionnaires were used to assess clinical outcomes. Seventeen stifles from fifteen dogs were evaluated radiographically. Mean error from target tibial plateau angle was 0.4 degrees. Anatomical-mechanical axis angles reduced from mean 2.9 degrees preoperatively to mean - 0.9 degrees postoperatively. Tibial tuberosity distalization was mean 5.0% of mechanical axis length, and mean reduction in mechanical axis length was 0.1%. Increased tibial plateau angles were noted in 8/17 stifles, with a mean of 9.6 degrees at short-term follow-up. Major complications were observed in 9/17 stifles. Long term follow-up (mean 832 days) was obtained with gait analysis in 8/15 dogs and with questionnaire in 11/15. Most dogs (9/11) were weakly to moderately affected by osteoarthritis symptoms. All values for peak vertical force and vertical impulse normalized to body weight exceeded local lower reference limits for normal dogs, indicating acceptable limb use. Satisfactory immediate and long-term clinical outcomes appear to be possible with this technique, but the high incidence of shorter-term complications may caution against the technique or the fixation and management described here.

Morphologic impact of four surgical techniques to correct excessive tibial plateau angle in dogs: A theoretical radiographic analysis

OBJECTIVE

To determine morphologic differences between four tibial osteotomy techniques used to correct excessive tibial plateau angle (eTPA).

STUDY DESIGN

Retrospective radiographic analysis.

SAMPLE POPULATION

Sixteen dogs (27 tibias) with eTPA.

METHODS

Virtual corrections of eTPA were performed on sagittal plane radiographs of canine tibia using four tibial osteotomy techniques and categorized into respective groups. Group A represented the center of rotation of angulation (CORA)-based leveling osteotomy (CBLO) and coplanar cranial closing wedge ostectomy (CCWO), Group B the tibial plateau leveling osteotomy (TPLO) and CCWO, Group C the modified CCWO (mCCWO), and Group D the proximal tibial neutral wedge osteotomy (PTNWO). Pre- and post-correction TPA, tibial length and mechanical cranial distal tibial angle (mCrDTA) were measured and compared.

RESULTS

Mean TPA prior to correction was 42.67 ± 6.1°. Post-correction mean TPAs were 10.47 ± 2.1°, 6.77 ± 1.6°, 4.76 ± 1.5°, and 7.09 ± 1.3° for Groups A, B, C, and D, respectively. TPA correction accuracy in Groups A and D varied least from target TPAs. Tibial shortening was documented in Group B in contrast to other groups. The greatest mechanical axis shift was identified in Group A.

CONCLUSION

Each technique achieved TPA < 14° despite having different effects on tibial morphology including alteration of tibial length, mechanical axis shift and variation in correctional accuracy.

CLINICAL SIGNIFICANCE

Despite all methods being able to correct eTPA, the choice of technique will affect morphology in unique ways and should be considered prior to surgery to consider the implications in a given patient.

Predicting tibial plateau angles following four different types of cranial closing wedge ostectomy

OBJECTIVE

To investigate how tibial long axis (TLA) shift affects the postoperative tibial plateau angle (TPA) in four cranial closing wedge ostectomy (CCWO) techniques.

STUDY DESIGN

In silico study.

SAMPLE POPULATION

A total of 15 client-owned dogs.

METHODS

Computed tomography (CT) scans of 15 client-owned dogs were reviewed using an open-source 3D computer graphics editor. Each computer-generated 3D tibia model underwent a CCWO, with cranial cortex alignment, in 10° increments up to 70° using each of the four previously described techniques. The TLA shift, TPA and mechanical tibial length (mTL) were calculated, using trigonometry, for each model. Equations for predicting final TPA were generated with linear regression.

RESULTS

A total of 433 3D computer generated tibial models were analyzed. With each technique, the TPA varied in a linear fashion within the studied range of wedge angles. The TLA shift and tibial shortening magnitude varied between the four different CCWO techniques, with maximum mTL reduction of ranging from 7.5% to 40.9%. All predicted TPAs using the generated equations were within the target range of 4-6°.

CONCLUSION

A linear relationship between ostectomy wedge angle and TPA correction was observed in this study, which allowed for generation of accurate corrective equations.

CLINICAL SIGNIFICANCE

These results allow extrapolation of the wedge angle required to reach a postoperative TPA of 5°, by considering the TLA shift. The use of the generated corrective equations may thus increase CCWO planning precision.

A mismatch of planning and achieved tibial plateau angle in cranial closing wedge surgery: An in silico and clinical evaluation of 100 cases

OBJECTIVE

(1) To determine whether Oxley's modified cranial closing wedge osteotomy (CCWO) results in a tibial plateau angle (TPA) of 5° in silico, (2) compare in silico to clinical postoperative TPA and (3) determine the impact of ostectomy distalization in silico.

STUDY DESIGN

Cross-sectional retrospective radiographic in silico study.

SAMPLE POPULATION

A total of 100 stifle radiographs; 90 dogs (small ≤25 kg = 84; large >25 kg = 16).

METHODS

Tibial plateau angles were measured preoperatively (TPAPre ), after in silico planning (TPAPlan ), and postoperatively (TPAPost ). Virtual ostectomies were evaluated for plate fit. Postoperative ostectomy position was measured. Virtual ostectomies were performed 5/7.5/10/15 mm from the patellar tendon insertion in 10 dogs from each preoperative TPA category (≤20°/21-25°/ 26-30°/31-35°/>35°). Comparisons for TPAPre , TPAPost , and TPAPlan were made between small and large dogs, and the outcome to the target 5° between TPA categories and ostectomy positions.

RESULTS

Mean ± SD TPAPre was 28.6 ± 6.2° and higher in small than large dogs. Mean TPAPlan was 7.6 ± 2.7°. Plate fit was appropriate in all. In silico, TPAs were greater than 5° except for cases with TPAPre  > 35°. Median TPAPost was 5.5° (-4-21) and was higher in small (7°) than large (4.5°) dogs. Postoperative ostectomy position was more distal than Oxley's guidelines. When distalized >7.5 mm in silico, the magnitude of under-correction increased.

CONCLUSIONS

Oxley's modified CCWO did not result in TPA of 5° in most cases. Ostectomy distalization exacerbated under-correction.

CLINICAL IMPACT

Current guidelines should be modified to achieve 5° TPA postoperatively.

Cranial closing wedge ostectomies for management of canine cranial cruciate ligament insufficiency: Comparison and geometric modelling of errors

Variants of the cranial closing wedge ostectomy (CCWO) may be used to manage cranial cruciate ligament deficient stifles by reduction of the tibial plateau angle (TPA). Concerns have been raised about predictability of achieving target TPA, limb shortening, axis shift, and distalization of the tibial tuberosity. Landmarks derived from tibial radiographs (n = 50) by 5 observers, along with outlines of the cranial and caudal proximal tibial cortices, were used to simulate six CCWO variants. Tested variants were Slocum-type (n = 2), modified (n = 2), isosceles, and anatomical-mechanical axis (AMA)-based CCWO. Observer specific landmarks were used to model pre- and postoperative errors in TPA measurement. Mean landmarks were used to compare key outcome variables between the variants, as well as modelling errors in positioning the wedge apex. Variants differed markedly in TPA, axis shift, mechanical axis length changes, and tibial tuberosity distalization, with more proximally positioned wedges performing better than distally positioned wedges. Errors in TPA identification appeared partially self-correcting due to altered axis shifts. Craniocaudal shifts in wedge apex position had the most severe effects on outcome variables, especially in shorter tibiae with greater initial TPA values. Recent CCWO variants are likely to achieve a satisfactory postoperative TPA with limited axis shift. The AMA-based CCWO technique appears to influence MA length and tibial tuberosity position the least, and apart from the effect on TPA where no advantage could be discerned, it appeared more robust in the face of wedge apex positioning errors than the other techniques.

Radiographic Comparison of Virtual Surgical Corrective Options for Excessive Tibial Plateau Angle in the Dog

OBJECTIVE

 The main aim of this study is to compare the impact of six proximal tibial osteotomies on the geometry and alignment of tibias with and without excessive tibial plateau angle (TPA).

STUDY DESIGN

 Mediolateral radiographs of 30 canine tibias were divided into three groups (n = 10/group): moderate TPA (≤34 degrees), severe TPA (34.1-44 degrees) and extreme TPA (>44 degrees). Six proximal tibial osteotomies were simulated on each tibia using orthopaedic planning software: cranial closing wedge ostectomy (CCWO), modified CCWO (mCCWO), isosceles CCWO (iCCWO), neutral isosceles CCWO (niCCWO), tibial plateau levelling osteotomy with CCWO (TPLO/CCWO) and coplanar centre of rotation of angulation-based levelling osteotomy (coCBLO). All tibias were reduced to a standard target TPA. Pre- and postoperative measurements were obtained for each virtual correction. Compared outcome measures included tibial long axis shift (TLAS), cranial tibial tuberosity shift (cTTS), distal tibial tuberosity shift (dTTS), tibial shortening and osteotomy overlap.

RESULTS

 Across all TPA groups, TPLO/CCWO had the lowest mean TLAS (1.4 mm) and dTTS (6.8 mm); coCBLO had the largest TLAS (6.5 mm) and cTTS (13.1 mm); CCWO had the largest dTTS (29.5 mm). CCWO had the largest degree of tibial shortening of 6.5 mm, while mCCWO, niCCWO and coCBLO resulted in minimal tibial lengthening (1.8-3.0 mm). These trends were generally conserved across different TPA groups. All findings had a p-value less than 0.05.

CONCLUSION

 mCCWO balances moderate alterations to tibial geometry while preserving osteotomy overlap. The TPLO/CCWO has the least effect on tibial morphology alteration, whereas the coCBLO results in the largest alteration.

Reported accuracy of cranial closing wedge ostectomy variants for management of canine cranial cruciate ligament insufficiency: A systematic review and meta-analysis

Concerns have been raised about the predictability of achieving appropriate tibial plateau angles (TPA), the occurrence of axis shift and tibial length reduction following cranial closing wedge ostectomy (CCWO). The primary objective of this review was to quantify typical errors in achieving target TPA with CCWO, with secondary objectives of assessing axis shift and length reduction. Retrospective or prospective studies of CCWO used as the primary treatment, from any date and in English, were eligible for inclusion. Searches were performed in EMBASE, Ovid MEDLINE, Agricola, Scopus, Web of Science, and CAB abstracts. Risk of bias was assessed, and data were screened for outliers and influential cases. Extracted data from 11 included studies were tabulated and underwent meta-analysis using R. Mean errors in TPA after CCWO ranged from - 0.6-2.9°, indicating the possibility of both under- and over-correction depending on the selected technique. Errors were relatively consistent for technique subgroups. Mean axis shifts ranged from 3.4° to 5.2°, and length reduction ranged from 0.4% to 3.2% of initial length, based on 6/11 and 3/11 studies, respectively. Data had high heterogeneity, many studies had small populations, and reporting standards were inconsistent. Concerns about the predictability of postoperative TPA may be overstated. With the limited data available, limb shortening does not appear to be a clinically important consideration. Axis shift will occur to varying degrees and must be considered during CCWO planning, as it influences the postoperative TPA. Careful choice of CCWO technique may allow clinicians to reliably achieve predictable TPA values.

Tibial Plateau Leveling Following Tibial Tuberosity Advancement: A Case Series

Persistent stifle instability is a recognized complication following tibial tuberosity advancement techniques (TTAT). The aim of this study is to report the feasibility and outcome of tibial plateau leveling techniques (TPLT) to treat dogs with persistent lameness, suspected to be secondary to persistent stifle instability, following (TTAT). Medical records of dogs presented for persistent lameness after TTAT were reviewed. Preoperative data included orthopedic examination, lameness score and radiographs. Inclusion criteria included performance of a surgery to address persistent lameness and suspected instability. Short-term follow up data included orthopedic examination and radiographs of the stifle. Long-term follow up was based on postoperative Liverpool Osteoarthritis in Dogs (LOAD) questionnaire. Seven dogs were included in the study. Mean subjective preoperative lameness score was 3 ± 1.53. Mean preoperative patellar ligament angle relative to the tibial plateau (PLA^TP) was 94° and mean tibial plateau angle (TPA) was 28°. Six dogs had tibial plateau leveling osteotomy and one had modified cranial closing wedge ostectomy. Mean postoperative PLA^TP was 79° and mean TPA was 5°. Mean subjective lameness score at follow up was 0.57 ± 0.49. Minor complications were present in 2 dogs and major complication in 1 dog. Mean LOAD questionnaire score was 6.6/52. TPLT can be performed after TTAT and may improve clinical function and stability in these cases in which persistent instability is suspected.

Comparison of tibial anatomical-mechanical axis angles and patellar positions between tibial plateau levelling osteotomy (TPLO) and modified cranial closing wedge osteotomy (AMA-based CCWO) for the treatment of cranial cruciate ligament disease in large dogs with tibial plateau slopes greater than 30° and clinically normal Labradors retrievers

Background

The objective of this study was to evaluate tibial anatomical-mechanical axis angles (AMA-angles) and proximodistal and craniocaudal patellar positions following tibial plateau levelling osteotomy (TPLO) and AMA-based modified cranial closing wedge osteotomy (CCWO) in large dogs with tibial plateau angle (TPA) > 30°, to compare these postoperative positions with those of a control group of healthy normal dogs, and to assess which procedure yields postoperative morphology of the tibiae and stifles that is most consistent with that of the unaffected group. This study also investigated whether the occurrence of patellar ligament thickening (PLT), which is commonly observed 2 months postoperatively after TPLO, is associated with misplacement of the osteotomy. A total of 120 dogs weighing more than 20 kg, 40 of which were control animals, were enrolled in this retrospective study. Stifles were radiographically evaluated preoperatively and postoperatively on the side with CCLR and on the healthy contralateral side and compared with clinically normal stifles. PLT was reassessed after 2 months.

Results

Significant decreases in median patellar height ratio were found after both procedures (TPLO 0.24 (0.05–0.8); CCWO 0.22 (0.05–0.4)). The postoperative craniocaudal patellar position and the median AMA angle differed significantly among the groups (P = 0.000) (TPLO 87.5% caudal to the AA and 3.12° (0.76–6.98°); CCWO 100% cranial to the AA and 0° (− 1.34–0.65°); control group 5% caudal to the AA and 0.99° (0–3.39°)).

At 8 weeks, PLT grade differed significantly in the two operated groups (P = 0.000) (TPLO 40% 0–2, 20% 2–4, 40% > 4; CCWO 98.8% 0).

Conclusions

TPLO and AMA-based CCWO are associated with significant decreases in patellar height; however, the PLT results 2 months postoperatively differed between the two groups; the decrease in patellar height and PLT were independent of osteotomy position in the TPLO group. Compared to TPLO, CCWO results in reduced postoperative AMA angles and craniocaudal patellar positions that more closely resemble those of unaffected dogs, suggesting that the CCWO procedure allows us to better correct the caudal bowing of the proximal tibia that is often associated with deficient stifles in large dogs with TPA > 30°.

Double-cut center of rotation of angulation-based leveling osteotomy for treatment of cranial cruciate ligament deficiency and excessive tibial plateau angle secondary to growth anomaly in two dogs

CASE DESCRIPTION

A 4-year-old female Staffordshire Bull Terrier (dog 1) and a 6-year-old male Yorkshire Terrier (dog 2) were evaluated because of left pelvic limb lameness.

CLINICAL FINDINGS

Both dogs had a partial rupture of the left cranial cruciate ligament associated with a unilateral excessive tibial plateau angle (51° in dog 1 and 41° in dog 2) secondary to a growth anomaly.

TREATMENT AND OUTCOME

Both dogs underwent a double-cut center of rotation of angulation-based leveling osteotomy combining rotation of the proximal fragment with a cranial closing wedge ostectomy. The procedure allowed leveling of the tibial plateau to a final angle of 11° in one dog and 10° in the other without perioperative complications. Both dogs had excellent functional outcomes ≤ 4 months after the surgery. No postoperative complications were reported during follow-up (12 months and 9 months for dogs 1 and 2, respectively).

CLINICAL RELEVANCE

Results for these dogs suggested that double-cut center of rotation of angulation-based leveling osteotomy can be considered as a viable treatment option for cranial cruciate ligament deficiency associated with excessive tibial plateau angle.

Cranial cruciate ligament rupture in small dogs (<15 kg): a narrative literature review

Small breed dogs (<15 kg) affected by cranial cruciate ligament rupture secondary to cranial cruciate ligament disease are usually middle-aged (mean age at presentation: 5.4 to 9.8 years); terrier breeds, miniature and toy poodles are over-represented. Small breed dogs have a different morphology of the proximal tibia compared to medium and large breed dogs with a steep tibial plateau angle (mean tibial plateau angle 28.8° to 36.3°), absent base of the flare of the tibial tuberosity and a caudally bowed fibula. There is a lack of evidence regarding the optimal management of cranial cruciate ligament rupture in small dogs. The treatment options consist of conservative management, extracapsular stabilisation, cranial closing wedge ostectomy, tibial plateau levelling osteotomy and tibial tuberosity advancement. The limited evidence available shows that conservative management is likely to result in prolonged recovery time (average time to recovery approximately 4 months). There is paucity of reports focussing on extracapsular stabilisation in small breed dogs, and questions have been raised regarding the early failure of the extracapsular suture subject to higher loads due to the steep tibial plateau angle of small breed dogs. Cranial closing wedge ostectomy and tibial plateau levelling osteotomy have been reported to have low major complication rates and good subjective outcomes. It is controversial whether tibial tuberosity advancement is a suitable technique in dogs with steep tibial plateau angle, which includes most small breed dogs.

Geometric modelling of CORA-based levelling osteotomy in the dog

Centre of rotation of angulation (CORA)-based levelling osteotomy (CBLO) is a recent addition to surgical procedures for stabilization of the cranial cruciate ligament-deficient canine stifle joint. Careful identification of the CORA location preoperatively and use of this location intraoperatively are required to ensure accurate correction of the tibial plateau angle. Limited data are available regarding the magnitude and source of potential errors during planning and execution of CBLO. A geometric model enabling isolation of various error sources is described. Landmarks were derived from tibial radiographs (n = 50) by 5 observers and used to define proximal and distal anatomical axes for simulation of CBLO. Observer-specific CORA locations with mean landmark data were used to assess planning errors, and simulated malpositioning of the CORA at 10 mm from the ideal location was used to assess surgical errors. Planning errors result mainly from tibial plateau misidentification, with CORA locations dispersed up to ±10 mm proximodistally from ideal (95% confidence). Malpositioning of the CORA during surgery causes equal and opposite changes in tibial plateau angle (TPA) and anatomical-mechanical axis angles, and varying degrees of translation and limb length changes. The magnitude of these changes is dependent on initial TPA and limb length, with smaller dogs and steeper tibial plateaus resulting in larger errors. Optimal planning and execution are required to achieve the planned outcome of CBLO. The main source of error in our simulation is identification of the tibial plateau. While both pre- and intraoperative errors influenced TPA, based on our geometric model the effect in larger dogs may not be clinically significant. If distalisation of the CORA is required during surgery, compensation of the CORA angle to maintain the target TPA is possible.

Modified cranial closing wedge osteotomy to treat cranial cruciate ligament deficient stifles with excessive tibial plateau angles: Complications, owner satisfaction, and midterm to long-term outcomes

OBJECTIVE

To report midterm to long-term outcomes of dogs with cranial cruciate ligament (CCL) rupture and excessive tibial plateau angles (TPA) treated with a modified cranial closing wedge osteotomy (m-CCWO).

STUDY DESIGN

Retrospective case series.

STUDY POPULATION

Dogs (n = 21) with CCL rupture and excessive TPA treated with m-CCWO (n = 28).

METHODS

Medical records, midterm and long-term follow-up radiographic examination records, Canine Orthopedic Index data, and owner surveys were reviewed to determine functional outcomes, owner satisfaction, and complications associated with the technique.

RESULTS

Tibial plateau angle decreased from 42.3° ± 4.8° preoperatively to 4.8° ± 3.3° after m-CCWO. No catastrophic complications occurred, while major and minor complications occurred in three of 28 and six of 28 stifles, respectively. Canine Orthopedic Index scores and owner surveys were available in 16 of 21 dogs at a median of 608 days postoperatively (range 279-1225). Functional midterm or long-term outcomes for these dogs treated with m-CCWO were excellent in eight dogs, acceptable in seven dogs, and unacceptable in one dog. Progression of osteoarthritis was noted on all midterm and long-term follow-up radiographs. All owners but one were satisfied.

CONCLUSION

Modified cranial closing wedge osteotomy was associated with an acceptable morbidity and resulted in satisfactory functional outcomes in most dogs of this series.

CLINICAL SIGNIFICANCE

Modified cranial closing wedge osteotomy should be considered as an alternative to treat CCL rupture in dogs with excessive TPA.