Guided TPLO study finds better osteotomy centering than freehand

CURRENT FULL VERSION: A new AJVR study is putting more data behind guided TPLO systems, reporting that a modular guide improved osteotomy centering accuracy compared with a freehand technique. The paper, published in 2026 and indexed in PubMed, evaluated the OssAbility system and concluded that guide use improved accuracy in the sagittal and frontal planes, addressing one of the most technically sensitive parts of TPLO execution. (pubmed.ncbi.nlm.nih.gov)

That matters because TPLO is widely used to manage cranial cruciate ligament disease in dogs, and centering the radial osteotomy has long been treated as a critical step. Prior literature has emphasized that osteotomy position should align closely with the intended center of rotation to avoid unintended changes in proximal tibial anatomy and postoperative mechanics. Even in experienced hands, freehand execution can produce measurable eccentricity, and a 2017 in vivo study of 231 TPLO procedures found a mean absolute distance of eccentricity of 3.0 ± 1.6 mm, with no significant improvement across a surgeon’s first, middle, and final case cohorts in that series. (veterinarypartner.vin.com)

In the new AJVR paper, investigators directly compared the modular guided approach with a traditional freehand method in a randomized controlled experimental design. Based on the abstract and indexed summary, the study’s main finding was improved TPLO centering and accuracy with the guide in both the sagittal and frontal planes. The study also tested whether surgeon experience changed performance, with the authors proposing that experience would improve freehand accuracy more than guided accuracy. (pubmed.ncbi.nlm.nih.gov)

The broader research landscape is moving in a similar direction. A 2026 Frontiers in Veterinary Science ex vivo study of a templated TPLO and implant guidance system found significantly improved osteotomy execution and less deviation from intended postoperative tibial plateau angle, while also reducing procedure time and technical errors in novice surgeons. That study’s authors argued that traditional TPLO can drift when surgeons center the cut relative to a jig pin rather than the intended osteotomy center, a problem that templated systems are designed to reduce. (doi.org)

The clinical stakes go beyond neat radiographs. A separate AJVR retrospective study of 312 stifles treated with TPLO found postoperative rotational instability in 77 cases, or 24.6%, defined as persistence of a positive tibial pivot test requiring placement of an antirotational suture. In multivariable analysis, chronic presentation was associated with lower odds of instability, while increasing lameness severity, complete cranial cruciate ligament rupture, and meniscal tear were associated with higher odds. Age, body weight, osteoarthritis score, and preoperative tibial plateau angle were not independently associated after adjustment. The practical takeaway is that lesion severity and acute presentation may matter more than baseline morphometrics when surgeons assess the risk of residual rotational instability and decide how carefully to test for it intraoperatively.

Direct outside reaction to the AJVR paper appears limited so far, but the commercial and training ecosystem around guided TPLO is clearly expanding. OssAbility describes its Guided TPLO platform as a patient-configured, single-use guide intended to reduce variables in osteotomy position and rotational correction, and the company is also promoting training and decision-support services around the system. That doesn’t substitute for independent clinical outcomes data, but it does suggest the study lands in a market already pushing toward more standardized, support-driven orthopedic workflows. (ossability.com)

There is also still uncertainty around how much any technical improvement changes longer-term disease progression. A Veterinary Evidence knowledge summary reviewing three comparative studies concluded that evidence is currently weak on whether TPLO is superior to tibial tuberosity advancement, or TTA, for reducing postoperative radiographic osteoarthritis. Two prospective trials pointed in opposite directions and neither found a significant difference, while a third retrospective study favored TPLO but was limited by the usual issues of sample size, confounding, blinding, and follow-up. In practice, that means surgeons still cannot confidently claim that choosing TPLO over TTA will meaningfully slow osteoarthritis based on the current literature alone.

At the same time, some follow-up data on TPLO durability are reassuring. A recent retrospective study in small-breed dogs under 10 kg found that TPLO achieved effective correction and maintained radiographic tibial plateau angle stability over time. Mean preoperative TPA fell from 31.23° to 4.68° immediately after surgery and measured 5.19° at 6 months or later, for a mean change of 0.52°. Although statistically significant, that shift remained below a previously reported 1.5° intraobserver measurement error, and body weight was not correlated with change. The authors concluded that long-term TPA correction in small dogs was radiographically stable.

Why it matters: For veterinary surgeons and referral teams, this is less about a new gadget than about whether TPLO can become more reproducible across operators and practice settings. If guided systems consistently improve centering, they could help reduce avoidable variation in plate placement, rotational correction, and load sharing, especially for general practitioners or lower-volume surgeons adding advanced orthopedics. That could also matter for case selection, training, mentoring, and conversations with pet parents about where a procedure should be performed and by whom. At the same time, the current evidence is still centered on technical accuracy, not yet definitive proof of fewer complications or better long-term function. The surrounding literature reinforces that point: rotational instability after TPLO is not rare, osteoarthritis comparisons with TTA remain unsettled, and even encouraging radiographic stability data do not by themselves answer the patient-outcome question. (pubmed.ncbi.nlm.nih.gov)

What to watch: The next step is prospective clinical validation: live-patient studies, complication rates, healing outcomes, meniscal and rotational stability measures, and whether guided TPLO changes the learning curve or economics of offering cruciate surgery in general practice. It will also be worth watching whether better centering translates into lower rates of postoperative rotational instability in higher-risk dogs, any measurable effect on osteoarthritis progression compared with other procedures such as TTA, and whether radiographic correction remains as stable in broader clinical populations as it appears to be in recent small-breed follow-up data. Until those data arrive, this study is best read as strong technical evidence in favor of guidance, not the final word on patient benefit. (pubmed.ncbi.nlm.nih.gov)