Tibial Diaphyseal Fracture Rates Following Tibial Tuberosity Advancement Rapid ( TTAR ) and Traditional Tibial Tuberosity Advancement ( tTTA ) A Knowledge Summary by Wye

<strong>PICO question</strong><br /><p>In dogs with cruciate disease, is the use of TTA Rapid (TTAR) compared to traditional TTA (tTTA) associated with a higher risk of tibial diaphyseal fractures?</p><strong>Clinical bottom line</strong><br /><p>Based on studies published between January 2013 and January 2018, the rate of tibial diaphyseal fractures as a complication of Tibial Tuberosity Advancement Rapid (TTAR) surgery is within the published limits of traditional Tibial Tuberosity Advancement (tTTA). In this period, seven studies were related to tTTA, comprising of four; one case series, two retrospective case-control studies, and one retrospective cohort study. Five case series were related to TTAR.  All evidence within this period has been observational (Level 3 and 4 evidence). No direct head-to-head comparison between the techniques has been studied. </p><br /> <img src="https://www.veterinaryevidence.org/rcvskmod/icons/oa-icon.jpg" alt="Open Access" /> <img src="https://www.veterinaryevidence.org/rcvskmod/icons/pr-icon.jpg" alt="Peer Reviewed" />


Limitations:
 The radiographic complications were evaluated by only one radiologist. The radiographic scoring system is subjective and may be prone to inter-operator variability. There is no control population (unilateral TTA) used for comparison and testing of the null hypothesis. Comparison was based on results of other studies. The outcomes of patients with major and minor complications were not reported. Non-radiographic complications were not reported. Statistical significance (P value) for comparing complications between forked and screw plates was not reported.

Sample size: 167 stifle joints
Intervention details:  All dogs received plated TTA by the same surgeon. Dogs with meniscal pathology were partially or completely resected.Dogs with intact meniscus were left in situ. Consecutive records were plotted retrospectively using cumulation summation technique (CUSUM) to measure cumulative success for clinical audit and competence of a single surgeon over time.

Study design: Retrospective case series
Outcome studied:  Cumulative success rates of a single general practitioner surgeon. Major and minor complication rates. Retrospective design. tTTA procedure was modified over time so there could have been more complications in earlier cases. Postoperative care was not standardised. Did not compare staged bTTA vs single-stage bTTA. Relative risks were not reported.

Intervention details:
 All dogs underwent arthrotomy or arthroscopy.
 No dogs received meniscal release. Partial meniscectomy performed in cases of meniscal injury. All dogs received plated Securos Surgical TTA XGEN system. All dogs received autologous cancellous bone graft into osteotomy space. All dogs received exercise restriction for 6 weeks.

Study design: Prospective case series
Outcome studied: Complications, lameness, thigh circumference, range of motion, radiographic osteoarthritis at 6 weeks, 6 months, and 1 year.

Limitations:
 Very small sample size. Utilised thigh circumference (TC) and range of motion (ROM) as a measure of limb use, as opposed to peak fracture.

Limitations:
 Meniscal findings and injury rate not reported. Minor complications were not defined. The outcomes were measured subjectively using visual analogue scales.A clinician was used to assess outcome with blinding and control but the control was not defined. Competency of the surgeon was not defined (specialist vs. resident vs. general practitioner). This study has a very small sample size for assessment of complication rates. There is no control group to assess if there would be improvement with no treatment.From this table, the rate of tibial diaphyseal fractures from tTTA (0-2.3%)compared to TTAR (0-4.17%) are roughly comparable.In the TTAR group, Dyall & Schmokel's (2017) report of 4.17% tibial diaphyseal fractures using TTAR on small breed dogs (< 15 kg) was notably higher than the other three studies.The higher fracture rate was attributed to the relatively large cage size, which may have overwhelmed the elasticity of the cranial tibial cortex, predisposing to fracture.If small breed dogs were excluded from the comparison then the rate of tibial diaphyseal fractures for TTAR would be 0-0.7%,which is within the published limits for tTTA (0-2.3%).A two-tailed T test (https://www.socscistatistics.com/tests/studentttest/Default2.aspx)comparing TTAR (0, 0, 0.7, 4.17) vs tTTA (0.18, 0.7, 0, 0, 2.27, 0, 1.1) reveals t-value of 0.7246 and p-value of 0.487105, showing a lack of significance at p < 0.05, although the sample size is very small.Interestingly, tibial tuberosity fractures, while not directly related to the PICO, occur more commonly across studies.In tTTA, a complete osteotomy of the tuberosity is held in place by a forked or screw plate.Fractures are generally attributed to poor plate and cage positioning, as well as narrow tuberosity width postosteotomy (Costa et al., 2017).In TTAR, the osteotomy is incomplete leaving the distal hinge intact.It should be noted that all evidence that met the inclusion criteria for this PICO is of low grade evidence and to date no head-to-head control trials have been done comparing tTTA to TTAR or other second-generation plateless techniques.Future studies could focus on which perioperative factors might have an impact on fracture complications.For example, the experience of the veterinary surgeon, the use of bone grafting, which may accelerate healing, the size and age of the patient, which may influence bone elasticity, as well as owner compliance and protective effect of external coaptation in the early postoperative period.Based on current evidence however, the rate of tibial fractures does not differ between tTTA and TTAR.Until data to the contrary becomes available, veterinary surgeons performing either technique should be cognizant of their ability to perform complex osteotomy, as well as audit their complications and compare them against published limits.Total relevant papers when duplicates removed

de 6 
Sousa et al., (2017) Plateless TTA Population: Dogs that received plateless TTA with complications of tibial diaphyseal fracture Sample size: 17 dogs; 11/17 received Orthofoam-MMP procedure, 6/17 received TTAR procedure Intervention details: All 17 dogs received revision surgery to correct tibial tuberosity fracture by various forms of internal fixation.Study design: Case series Outcome studied: Outcome, major and minor complication following repair of tibial diaphyseal fracture secondary to complication of plateless TTA techniques.Overall complication rate -8/17 (47%)  Minor complication rate -3/17 (17.6%)  Major complication rate -5/17 (29.4%)  Surgical site infection -4/17 (23.5%)PICO  TTAR  N = 6  Major complication -0/Minor complication -2/6 Limitations:  Small sample size -6 TTAR and 11 Orthofoam-Modified Maquet Procedure. Variation in surgeons managing complication -six boarded specialist vs. four RCVS Certificate qualified veterinary surgeons. Owner compliance to original procedure was not measured or accounted for. Incidence of these tibial diaphyseal fractures could not be determined. No comparison with fracture complications from traditional TTA methods.Veterinary Evidence ISSN:2396-9776 Vol 4, Issue 1 DOI: http://dx.doi.org/10.18849/ve.v4i1.179next review date: 05 Mar 2021 p a g e | 13 of 18Appraisal, application and reflectionSince the advent of tTTA in 2002(Montavon et al., 2002), various second generation TTA procedures have been invented.These techniques (TTAR, Orthofoam-MMP, MMT, TTA-2) utilise custom saw guides to aid the surgeon in producing an incomplete osteotomy of the tibial tuberosity.They have different implant designs, and they eliminate the use of a supporting plate(Ness 2016Samoy et al., 2015, Bleakley 2015, Brunel et al., 2013).These techniques are generally aimed at the non-specialist surgeon and are marketed to be simpler than tTTA while offering comparable results.A recent case series of 17 dogs (de Sousa et al, 2017) suggests that tibial diaphyseal fractures may be a well-recognised catastrophic complication of second generation TTA techniques.However, the study design could not evaluate the actual incidence or prevalence of this complication.

Figure 1 :
Figure 1: Example of tibial diaphyseal fracture as a complication of TTAR technique.

dogs had tibial diaphyseal fractures.
Incidence of major and minor complication rates associated with tTTA in Boxers vs. non-Boxers.

/91 (1.1%) cases had tibial diaphyseal fracture
Postoperative rehabilitation was performed on some dogs and not others, which may influence TC and ROM. Clinical outcomes were subjectively measured using lameness score. Follow up radiographic signs of osteoarthritis were measured subjectively by one certified radiologist.Major and minor complication rates of TTA compared to TPLO in large breed dogs.The null hypothesis is that there is a difference in major complications between the two techniques, based on medical records.The power of the study was not indicated. Authors did not declare how many dogs were censored and excluded for not meeting the inclusion criteria. Lack of randomisation. Reliance on medical record accuracy. Declared conflict of interest from one of the authors, who receives royalties for Securos Surgical XGEN TTA system.Outcome was based on subjective clinical exam. Number of cage size and number of breeds were reported but not correlated against each other. No control group for comparison.

10 of 18 Sample size: 50 dogs Intervention details:
 All dogs received amoxicillin clavulanic acid 8.75 mg subcutaneously preoperatively. All dogs received TTAR surgery. All dogs received meniscal release. All dogs received hydroxylapatite bone paste onto osteotomy gap. All dogs had external coaptation for 2-3 days postoperatively. All dogs received postoperative antibiotics for 5 days.Outcomes, minor and major complication rates.

0% of dogs developed tibial diaphyseal fracture Limitations
:  Postliminary meniscal injury not reported. Unclear if SSI did not develop or was unreported. Small sample size. Short follow-up times (3 months). Not tested against a control group. Not all dogs received surgery with the aid of a saw guide. Outcome was based on subjective clinical exam only. Conflict of interest that the developer of the technique is also the primary author.9. Dyall & Schmokel (2017) TTAR Population: Small breed dog -mean weight 9 kg (4.8-15 kg) Sample size: 48 stifle joints Intervention details:  40 small breed dogs (48 stifle joints) received TTAR surgery.19/48 stifle joints received TTAR with Maquet hole, 29/48 had no Maquet hole. No dogs received meniscal release. No dogs received bone graft. All dogs were on exercise restriction for 6 weeks.Veterinary Evidence ISSN:2396-9776 Vol 4, Issue 1 DOI: http://dx.doi.org/10.18849/ve.v4i1.179next review date: 05 Mar 2021 p a g e |

11 of 18 Study design: Retrospective case series Outcome studied:
Lameness and postoperative complications at 6 weeks were measured by clinical examination and owner questionnaire assessment at mid-to long-term follow up (median 72 weeks).

Table 2 :
Based on recent (< 5 years) studies relevant to the PICO, tibial diaphyseal fractures are reported in the table.While not directly related to the PICO, tibial tuberosity fractures are also included.
Samoy et al. (2015)7)2017)al hinge were considered as tibial tuberosity fractures across the TTAR studies(Butterworth & Kydd (2017),Samoy et al., (2015),Dyall & Schmokel (2017),Arican et al., (2017)).Despite the added risk of the distal hinge fracture for TTAR, the tibial tuberosity fracture rate of 0.5-9.1% for tTTA and 1.3-11.7%forTTARdoes not differ significantly at p < 0.05, with two-tailed T test showing t-value of -0.91676 and p-value 0.378929.In addition, the 2/50 tibial tuberosity fractures inSamoy et al. (2015)happened before the development of a dedicated saw guide.The TTAR has since been modified to exclude the use of the Maquet hole at the distal end of the incomplete osteotomy while utilising a longer osteotomy.This is facilitated by a dedicated saw guide, allowing an accurate cut.It is yet unknown if this will lead to reduced tuberosity and diaphyseal fractures.Proot & Corr's (2013) clinical audit suggests that it takes 22 tTTA procedures to gain acceptable competence.To date, a similar clinical audit has not been published for TTAR and it is unknown if major complications such as tibial fractures are more common in the hands of inexperienced veterinary surgeons.It is also unclear from the data how often tibial fractures are due to faults in the technique or faults in the postoperative care.