Outcome and owner assessment after single-session bilateral tibial plateau leveling osteotomy in 127 dogs

Abstract

Objective

To retrospectively evaluate complication rates following bilateral tibial plateau leveling osteotomy (TPLO) as well as owner assessment of outcomes and post-operative management.

Methods

Medical records of dogs presenting with bilateral cranial cruciate ligament (CCL) disease that underwent single-session bilateral TPLO from 2015 to 2019 in 1 referral practice were retrospectively reviewed. A non-validated questionnaire was sent to the owners to assess their ability to cope during the rehabilitation period, as well as procedure outcome.

Results

In total, 127 dogs were included for analysis. The overall complication rate was 16.5% (minor complication rate 9.4% and major complication rate 10.2%). Of the 50 owners that answered the questionnaire, 31 (62%) did not need to use sling support at home at any time and 10 (20%) used sling support for < 1 wk. Furthermore, only 1 owner indicated that they would not choose to do a bilateral TPLO surgery again.

Clinical significance

Bilateral single-session TPLO surgery performed by an experienced surgeon had a similar outcome and complication rate to that of unilateral TPLO surgery. Most owners reported that postoperative care of their dog was not difficult.

Introduction

Cranial cruciate ligament (CCL) disease, the most common cause of pelvic limb lameness in dogs (1,2), is considered a degenerative process in most dogs (3–6). The incidence of bilateral CCL disease has been reported to vary from 18 to 61% during a dog’s lifetime, whereas simultaneous bilateral CCL rupture has been reported to affect 4.3 to 27% of dogs with CCL disease (7–12).

There are numerous procedures described for management of CCL rupture in dogs, with tibial plateau leveling osteotomy (TPLO) being 1 of surgeries most often performed. The procedure has a very good outcome and when performed as a unilateral technique, the reported complication rate was 14 to 28% (11,13). Furthermore, the complication rate after bilateral TPLO surgeries conducted during a single session has been reported to be similar to that of staged procedures, although some of these studies included relatively small numbers (14–16). Only 1 large study has been published (17) and without additional reports, it is hard to interpret the significance of its results.

Our primary aim was to retrospectively evaluate complication rates following bilateral TPLO, with a secondary aim of reporting owner assessment of outcomes and post-operative management. Where possible, risk factors associated with complications were identified. We hypothesized that single-session bilateral TPLO has complication rates comparable to unilateral TPLO surgery. We also hypothesized that owners can manage these dogs postoperatively without difficulty.

Materials and methods

The medical records of all bilateral TPLO procedures performed at Anderson Moores Veterinary Specialists from April 2015 to December 2019 were reviewed. All TPLO procedures were performed by, or under direct supervision of, an experienced Board-certified surgeon.

Inclusion criteria included dogs for which complete medical records, including post-operative re-examination, were available. Dogs were excluded if records did not include the following: breed, body weight, sex, neutered status, presence of concurrent orthopedic disease, details of meniscal damage, CCL tear type, osteotomy blade size, implant size, time after first recheck, lameness at recheck, and all major and minor intra- and postoperative complications. Cruciate ligaments were examined in all joints by “mini” cranio-medial arthrotomy and to identify meniscal tears and treat them as necessary. Partial CCL tears were excised at the discretion of the surgeon. Meniscal release was not performed. A jig was not used in any dog. All procedures used Synthes locking TPLO plates with a combination of cortical and locking screws, with the plate applied to the medial aspect of the tibia. Wounds were closed with polydioxanone (PDS; Ethicon, Raritan, New Jersey, USA) and intradermal poliglecaprone (Monocryl; Ethicon). Additional parameters analyzed included: surgical time, tibial plateau angle (TPA) pre- and post-surgery, days after surgery to weight-bearing, and days of hospitalization post-surgery. Complications were divided into major complications (those that required medical or surgical treatment) and minor complications (those that did not require additional medical or surgical treatment), consistent with proposed guidelines (18).

Owners’ assessment of outcome was obtained through a non-validated questionnaire (Supplementary file, available online from: www.canadianveterinarians.net) sent by email and postal mail. All dogs had a post-operative recovery time of at least 3 mo at the time of the survey.

Anesthetic protocols were supervised by Board-certified anesthesiologists and epidural anesthesia was performed in all dogs [preservative-free morphine (0.2 mg/kg), ropivacaine (1 to 2 mg/kg), lidocaine (2 mg/kg), or bupivacaine (1 mg/kg) based on the anesthetist’s preference]. Prophylactic cefuroxime (20 mg/kg) was administered intravenously 30 min before surgery and every 2 h until surgery ended. Oral cephalexin (20 mg/kg) was used as a postoperative antibiotic for 7 d, as recommended (19).

In some cases, a modified Robert Jones bandage was placed on each limb for 6 to 24 h depending on surgeon preference. Pre- and post-operative radiographs were obtained for all patients to measure TPA and confirm degree of rotation, implant placement, and identify intraoperative complications. Post-operative analgesia protocol was based on pain score (short form of the Glasgow composite measure pain scale), including meloxicam, SC, 0.1 to 0.2 mg/kg, methadone, IV, 0.1 to 0.3 mg/kg, q4 to 6h, and additional paracetamol, IV, 10 mg/kg q8h, if required. Dogs were discharged once they were ambulatory. Home analgesia was meloxicam, PO, 0.1 mg/kg, q24h or carprofen, PO, 4 mg/kg, q12h in all cases, and paracetamol, PO, 10 mg/kg, q8h or tramadol, PO, 2 mg/kg, q8h, if required.

Post-operative re-examinations were scheduled at 6 to 8 wk after surgery, at which time a clinical examination and orthogonal radiographic assessment was performed by a Board-certified surgeon or resident under their supervision.

Statistical analyses

The statistical analysis was performed using R Core Team 2020 software (R Foundation for Statistical Computing, Vienna, Austria). Initially, exploratory data analysis (EDA) of the whole data set was performed and descriptive statistics were obtained, considering all variables, despite some not being present in all dogs.

Spearman correlation analyses were performed between the following variables: breed, sex, age, weight, neutered status, presence of concurrent orthopedic disease, right meniscus affected, left meniscus affected, right CCL tear type (complete, partial, or minor), left CCL tear type (complete, partial, or minor), plate size, osteotomy blade, surgical time, right TPA preoperative, right TPA postoperative, left TPA preoperative, left TPA postoperative, intraoperative complications, days hospitalized, days after surgery to weight-bearing, weeks at recheck, presence of lameness at recheck, implant concerns, presence of minor complications, presence of major complications, treatment used, and outcome. A correlation was considered significant if r > 0.334. In addition, Fisher’s Exact test or Student’s t-tests were used to determine if the variables were related (a dependency relationship existed) between them and complication variables. If variables were dichotomous, a contingency table and Fisher’s Exact test were performed. Non-dichotomous variables were further studied. If they were normally distributed (assessed with the Shapiro-Wilk test), a Student’s t-test was used to check for dependency. If they were not normally distributed, a Wilcoxon signed-rank test was used. A P-value was generated for each variable, with P < 0.05 considered significant.

Results

In total, 129 bilateral TPLO procedures were performed from April 2015 to December 2019; 127 dogs met the selection criteria and were evaluated for this study.

The most common breed was golden retriever (n = 9), followed by Rottweiler (n = 8), and Labrador retriever, Staffordshire bull terrier, boxer, and West Highland white terrier (n = 7 each); representing 7.1, 6.3, and 5.5% respectively. “Crossbred” was the most numerous category with 32 dogs (25.2%).

The mean body weight was 25.8 kg (range: 6.7 to 65.6 kg) and the mean age was 7 y (range: 1 to 13 y). Fifty-five (43.3%) were neutered males and 54 (42.5%) neutered females, 12 (9.4%) were intact males, and 6 (4.7%) were intact females. Eight dogs presented with concurrent orthopedic problems in their pelvic limbs: 1 dog with bilateral medial patellar luxation Grade 2/4, 1 with unilateral medial patellar luxation Grade 3/4 (both dogs treated with block sulcoplasty at the time of the TPLO surgery), 3 with untreated bilateral medial patellar subluxation, 1 with unilateral hip dysplasia, 1 with femoropatellar crepitus, and 1 with unilateral severe stifle cartilage erosion for chronic CCL disease treated with the DeAngelis technique 2 y previously. All 127 dogs had a post-operative examination and radiographic assessment.

Surgery

The cranial cruciate ligament was completely torn in 66/127 (51.9%) dogs and partially torn in 61 (48.1%) in the right stifle, whereas in the left stifle, it was completely torn in 64 (50.4%) and partially torn in 63 (49.6%). The CCL was excised in at least 1 stifle in 103 (81.1%) dogs. The medial meniscus of the right stifle was damaged in 35/127 (27.6%) dogs, the medial meniscus of the left stifle in 32 (25.2%) dogs, and it was bilaterally damaged in 19 (15%) of the 127 dogs.

The mean surgical time was 97.7 min, with a range of 50 to 165 min.

Recovery and follow-up

The interval for dogs to walk after surgery (unaided or with sling support) was available for 97 dogs. Seventy-four dogs (76.3%) were walking on the day of surgery, 22 (22.7%) started to walk 1 d after surgery, and only 1 dog needed 2 d until it was able to walk by itself. There was no relation between time to walking and meniscal injury, length of surgery or body weight of the patient, but it was positively correlated with the right and left TPA pre-surgery (r = 0.38 and 0.34, respectively), taking more time to walk for those dogs with steeper pre-operative TPA, and negatively correlated with the presence of a complete CCL tear in the left stifle (r = –0.38), needing less time to walk.

Information on duration of hospitalization was available for all 127 dogs. Eighty-nine dogs (70.1%) spent 1 night in hospital after surgery, 35 dogs (27.6%) stayed 2 nights, and only 4 dogs (3.1%) were hospitalized for 3 nights after surgery.

All dogs were re-examined from 4 to 10 wk (mean: 6.5 wk) after surgery. Lameness was absent or minimal with full range of motion, comfortable and stable tibial thrust, with expected healing and no implant concerns at the radiographic examination in 116 of 127 dogs. Four dogs had moderate lameness and 7 had considerable lameness.

Complications

Intraoperative complications occurred in 16 dogs (Table 1). The occurrence of intraoperative complications was not associated with development of post-operative complications.

Table 1.

Summary of intraoperative complications after single-session bilateral tibial plateau leveling osteotomy in dogs.

Intraoperative complications	Number of occurrences
Profuse hemorrhage from osteotomy cut or drilled hole	5
Fibula fractured or accidentally cut	3
Drill bit or temporary K-wire broken and left in the bone	3
Intra-articular screw placement	2
Screw head stripped	2
Regurgitation	2
Visible thermal damage to bone during sawing	1
Bone cortical defect after screw placement	1

Twenty-one of the 127 dogs (16.5%) had at least 1 complication. There were 12 (9.4%) dogs with minor complications, and 13 (10.2%) with major complications. The total number of complications was 25, with 3 dogs having both minor and major complications, and 1 dog with 2 major complications (late meniscal injury and septic arthritis). There were no significant statistical relationships or any correlation between presence of minor or major complications and the other variables. Major and minor postoperative complications are summarized in Table 2.

Table 2.

Summary of minor and major complications after single-session bilateral tibial plateau leveling osteotomy in dogs.

Minor complications	Number of dogs (%)	Percent of minor complications	Percent of total complications	Body weight (kg)	TPLO plate used (mm)
Fibular fracture, healed	4 (3.2%)	33.33	16	29.3	3.5
				65.6	3.5 broad
				33.4	3.5
				42.4	3.5 broad
Seroma	2 (1.6%)	16.66	8	49.1	3.5 broad
				31.7	3.5
Thermally induced osteonecrosis	2 (1.6%)	16.66	8	39	3.5 broad
				15.2	2.7
Pain/discomfort	3 (2.4%)	25	12	10.8	2.4
				38	3.5 broad
				27.5	3.5
Tibial tuberosity fracture, minimally displaced	1 (0.8%)	8.33	4	11.6	2.4
Major complications	Number of dogs (%)	Percent of major complications	Percent of total complications	Body weight (kg)	TPLO plate used (mm)
Surgical wound infection	3 (2.4%)	23.08	12	30.4	3.5
				31.1	3.5
				29.3	3.5
Septic arthritis	2 (1.6%)	15.38	8	40	3.5 broad
Exuberant wound granulation tissue (from licking)	1 (0.8%)	7.69	4	17.4	2.7
Implant failure/problem	1 (0.8%)	7.96	4	33.4	3.5
Late medial meniscal injury	6 (4.7%)	46.15	24	23.5	3.5
				38.4	3.5
				33.7	3.5
				37	3.5 broad
				33.7	3.5 broad
				31.7	3.5

Questionnaire

The questionnaire was completed by 54 owners; 50 had complete data sets that were used for analysis. Owners reported that 62% (31/50) of dogs did not need sling support at any point of the post-operative recovery, 20% (10/50) needed support for < 1 wk, 14% (7/50) for 1 to 2 wk, and only 2 cases (4%) needed sling support for > 2 wk. One owner stated that they would not choose to do a bilateral surgery again due to the difficulty in managing the dog postoperatively; their dog was a 65.6 kg Leonberger.

In the first month after surgery, 12% (6/50) of dogs had major or minor complications (7 complications in total), with seroma that resolved without specific treatment being 57.1% of these complications. From 1 mo to 1 y after surgery, 8% (4/50) of dogs developed complications, and the percentage of complications in those dogs with more than 1 y follow-up was only 8.7% (4/46). Sixty-six percent (33/50) of dogs returned to normal use of the legs without lameness within 3 mo after surgery, 18% (9/50) needed 3 to 6 mo to recover fully, 14% (7/50) reached a normal level after 6 mo, and only 1 owner (2%) reported that their dog never returned to normal activity without lameness.

Most dogs did not need long-term non-steroidal anti-inflammatories (76% never, 10% sporadically), and just 5 dogs (10%) needed them permanently or very frequently.

Discussion

To the authors’ knowledge, this is the largest retrospective study of bilateral TPLO surgeries performed in a single session. The objective was to analyze and summarize complications after a single-session bilateral TPLO procedure and compare them to previous unilateral and bilateral studies, as well as assessing owner perceived outcome.

The incidence of complications in our study (16.5%) was similar to those reported in unilateral TPLO studies (11.4 to 28%) (11–13). We defined major complications as those that needed medical or surgical treatment, whereas some TPLO studies defined major complications as those cases that needed surgical management (major: 3.1 to 6.6%; minor: 8.2 to 8.3%) (12,13). If we had used the same criteria as these earlier studies, our major complication rate would be 5.5%, as in previous reports.

With respect to previous single-session bilateral TPLO studies, the rate of total complications was reported to be 25% or higher, with major complication rates varying from 10.1% (in a paper that classified major complications as requiring surgical management or persistent lameness for > 12 wk) (16) to 25%, approximately twice that of our results (14,15,19).

Tibial tuberosity fracture was identified as a potential complication in single-session bilateral TPLO procedures, being described as 12 to 40 times more likely to occur than in a unilateral procedure, in which the rate varies from 0.4 to 9% (12,13,15,16,20). There was only 1 case in our study (0.8% of dogs) in which the tibial tuberosity fractured; however, it was minimally displaced and did not require additional treatment.

Another reported complication is the presence of post-TPLO patellar luxation (< 1%) (11). However, in our study, no dogs had a patellar luxation secondary to TPLO surgery. Surgical site infections after TPLO surgeries were 3.9% in our study, similar to previous reports of 2.3 to 25.9% (21–25).

The incidence of medial meniscal injury varied from 33.2 to 48% via craniomedial arthrotomy evaluation and up to 83% via arthroscopy in dogs with CCL injury (11,12,26–29). In our study, the presence of medial meniscal injury in any leg at the time of surgery was 38%, presenting bilaterally in 15.5% of dogs, less than 1/3 of that previously reported (48% bilaterally) (28). Arthroscopic evaluation is the most accurate technique for visualizing the meniscus (29) having greater postoperative recovery (30), but craniomedial arthrotomy and probing is often performed as it is easier and faster. The late meniscal injury rate in our study was 4.7%, similar to previous reports of 1.9 to 27.8% (12,27,29,31–34). Therefore, we inferred that the risk of developing a late meniscal injury was not increased by performing a single-session bilateral TPLO surgery or by performing a craniomedial arthrotomy.

None of the patients presenting with other pelvic limb orthopedic problems developed complications, indicating that there was no higher incidence of complications in those cases that underwent a TPLO surgery with a simultaneous other orthopedic disease.

When single-session versus staged procedures are compared, the benefits of simultaneous bilateral TPLO procedures include a shorter convalescence and less monetary cost for the owners. However, these benefits must be balanced against more prolonged anaesthesia.

Post-operative management is often a concern when performing bilateral surgeries simultaneously. In our study, the interval from surgery to walking was longer in those patients with a steeper TPA pre-surgery and lower in those with a complete CCL tear in the left stifle. One concern is often the ability of the dog and the owner to cope during rehabilitation. From the questionnaire results, only 4% of those surveyed felt that their dog needed sling support during walking for > 2 wk, and only 1 owner struggled to manage the situation at home due to the large size of their dog. Overall, 84% of owners reported that their dog’s limb use had returned to normal within 6 mo.

The main limitation to this study is that it was based on retrospective data. Another limitation is that most of the dogs were not reassessed after the first postoperative recheck and longer-term outcome data was based on owner assessment. This, coupled with the fact that less than half of the owners answered the questionnaire, should be considered when evaluating the outcome data.

In conclusion, bilateral single-session TPLOs performed by an experienced surgeon resulted in a similar outcome to unilateral TPLO surgery with no significant increase in risk or complications. In addition, based on our survey, most owners were able to cope with management of their dogs at home after surgery. It is hoped that this additional study into bilateral TPLO will add further weight to the current literature in favor of this approach to dogs with bilateral cruciate disease.