KNOWLEDGE SUMMARY

Keywords: CRANIAL CRUCIATE LIGAMENT; OSTEOARTHRITIS; MODIFIED MAQUET PROCEDURE; TIBIAL PLATEAU LEVELLING OSTETOMY; TIBIAL TUBEROSITY ADVANCEMENT

In dogs with ruptured cranial cruciate ligament, is TPLO superior to TTA in reducing postoperative radiographic osteoarthritis?

William Grech, BVM&S, B.Pharm (Hons), Cert AVP (SAS), PgC (SAS)^1*

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¹ Gedrin House, Pope John Paul II Street, Victoria, Gozo, Malta, VCT9048
* Corresponding author email: williamsvetsurgery@hotmail.com

Vol 11, Issue 3 (2026)
Submitted 10 Jul 2025; Published: 10 Jul 2026
DOI: https://doi.org/10.18849/ve.v11i3.749

PICO question

In dogs with a naturally occurring ruptured cranial (anterior) cruciate ligament [P] does surgical treatment using tibial plateau levelling osteotomy (TPLO) [I] compared to a surgical repair using tibial tuberosity advancement (TTA) [C] result in a reduction in the risk of developing postoperative osteoarthritis? [O]

Clinical bottom line

Category of research

Treatment.

Number and type of study designs reviewed

Three papers were reviewed. These were a prospective, randomised, non-controlled clinical trial; a prospective, randomised, controlled clinical trial; and a retrospective, non-controlled, blinded cohort study.

Strength of evidence

Weak.

Outcomes reported

The first clinical trial showed that TTA was associated with less osteoarthritis (OA) progression than TPLO at 6-month follow-up. However, the opposite was reported in the second clinical trial, where less OA was recorded following TPLO than TTA surgery. In both the first and second studies, the difference between groups was not significant. The third study reports a significant increase in OA score in TTA over TPLO group at end of follow-up period. Despite the third study claiming a noticeable difference in recorded OA between these two surgeries, evidence is presently scant.

Conclusion

At the time of writing of this Knowledge Summary there is minimal evidence to conclude either TTA or TPLO reduces the rate of postoperative osteoarthritis progression for dogs treated for naturally occurring cranial cruciate ligament rupture.

Additional comments and caveats

All three studies possess various limitations, such as a lack of controls, absent confidence intervals, lacking blinding, small sample sizes, presence of confounders, bias, and short follow-up, all of which limit the value of their conclusions.

How to apply this evidence in practice

The application of evidence into practice should take into account multiple factors, not limited to: individual clinical expertise, patient’s circumstances and owners’ values, country, location or clinic where you work, the individual case in front of you, the availability of therapies and resources.

Knowledge Summaries are a resource to help reinforce or inform decision making. They do not override the responsibility or judgement of the practitioner to do what is best for the animal in their care.

Clinical scenario

An eight-year-old female spayed Labrador presented with hindlimb lameness while playing. Clinical examination revealed effusion of the right stifle joint and a positive cranial drawer/tibial compression test. Radiography revealed right stifle effusion. A diagnosis of a complete cranial cruciate ligament rupture was made. The client was informed about two osteotomy techniques for the treatment of a ruptured cruciate ligament, TPLO and TTA. Both techniques are associated with the progression of osteoarthritis (Livet et al., 2019; Knebel et al., 2020; Moore et al., 2020). Is there evidence that TPLO surgery is associated with a lower progression of OA than TTA?

The evidence

There is no clear consensus among studies reviewed about which surgery provides the best outcome in reducing development of OA (Livet et al., 2019; Knebel et al., 2020; Moore et al., 2020). Progression of OA is seen in both TPLO and TTA surgery, with two (Knebel et al., 2020 and Moore et al., 2020) out of three studies indicating that less is seen after TPLO surgery. The cohort study by Moore et al. (2020) was the only study out of three which concluded that TPLO surgery leads to a better outcome than TTA, however the difference reported in radiographic scoring and owner questionnaires, between both surgeries is not clinically meaningful after a three-year follow-up. Moreover, this study lacked a control group, and samples were not randomised. In addition, bias was present in the study with the TPLO group nearly four times the size of the TTA group. Livet et al. (2019) demonstrated that in either treatment group a rise in median OA score was observed, with TPLO dogs scoring slightly higher scores than TTA. However, these findings were not found statistically significant. In summary, there is no conclusive evidence to support the clinician that TPLO is superior to TTA in reducing radiographic progression of OA postoperatively.

Summary of the evidence

Knebel et al. (2020)

Outcome after Tibial Plateau Levelling Osteotomy and Modified Maquet Procedure in Dogs with Cranial Cruciate Ligament Rupture

Aim: To compare outcomes in tibial plateau levelling osteotomy (TPLO)/Modified Maquet Procedure (MMP) procedures using radiographic and force plate analysis.

 

Livet et al. (2019)

Comparison of Outcomes Associated with Tibial Plateau Levelling Osteotomy and a Modified Technique for Tibial Tuberosity Advancement for the Treatment of Cranial Cruciate Ligament Disease in Dogs: A Randomized Clinical Study

Aim: To compare outcomes and complications in dogs with cranial cruciate ligament (CCL) disease after tibial plateau levelling osteotomy (TPLO)/tibial tuberosity advancement (TTA) surgery.

 

Moore et al. (2020)

Extended long-term radiographic and functional comparison of tibial plateau leveling osteotomy vs tibial tuberosity advancement for cranial cruciate ligament rupture in the dog

Aim: To objectively assess osteoarthritis (OA) progression in dogs undergoing tibial plateau levelling osteotomy (TPLO)/ tibial tuberosity advancement (TTA) surgery over a 3-year period.

 

Appraisal, application and reflection

The literature search retrieved three studies (Livet et al., 2019; Knebel et al., 2020; Moore et al., 2020) that were found pertinent in examining whether tibial plateau levelling osteotomy (TPLO) is better than tibial tuberosity advancement (TTA) surgery in reducing progression of osteoarthritis (OA). Appropriate methods employed in the above studies to address this clinical question were radiography (Livet et al., 2019; Knebel et al., 2020; Moore et al., 2020), kinetic gait analysis (Livet et al., 2019; Knebel et al., 2020) and client questionnaires (Livet et al., 2019; Moore et al., 2020). In Knebel et al. (2020), a comparison is made between TPLO and Modified Maquet Procedure (MMP), a modification of the TTA procedure. Livet et al. (2019) and Knebel et al. (2020) followed participants for only 6 months, while in Moore et al. (2020) the follow-up was more than 3 years.

All studies reported the progression of OA on radiography for both TPLO and TTA groups. In Livet et al. (2019), OA was seen to advance more in the TPLO than the TTA group with no significant difference found between categories. On the contrary, in the Knebel et al. (2020) study, MMP (TTA) group showed more progression in OA than TPLO group. However, in this study only medians and ranges were provided, and no p-values were reported on the OA follow-up results. Notably, Moore et al. (2020) showed a significant difference in OA scoring between the TPLO and TTA group, with TTA associated with more progression of OA than its counterpart. Despite the discovery of significance, the difference in means between groups is infinitesimal, thus concealing any significance there might be between the two surgeries. Despite all studies report progression in OA, Knebel et al. (2020) and Livet et al. (2019) observed no difference in limb function between the two operative methods using objective methods (e.g.: force plate analysis) at end of follow-up. Moore et al. (2020) claim that clients observed better limb function in dogs undergoing TPLO than TTA, however this is based on a subjective evaluation (questionnaire). Therefore, overall, there is poor correlation between documented radiographic OA progression and observed clinical outcome between the two surgeries.

In Knebel et al. (2020) and Livet et al. (2019) postoperative complications were reported that required partial meniscectomy. Some argue that partial meniscectomy is known to lead to the development of OA (Cox et al. 1975; Pozzi et al., 2008). Others claim the contrary (Rayward et al., 2004; Ertelt & Fehr, 2009). Moreover, in the Moore et al. (2020) study, the meniscus was released in 66/133 (49.6%) stifles at the time of surgery. A prospective, blinded, controlled, in-vivo experimental study has shown that meniscal release in dogs resulted in radiographic evidence of OA (Luther et al., 2009). Some of the reported OA progression might have occurred due to meniscal release performed intraoperatively and irrespectively of surgical method. Therefore, such procedures can have a confounding effect on the progression of OA and in any future studies it is best that dogs with meniscal lesions are excluded.

A control group was only included in the Knebel et al. (2020). A lack of controlled clinical trials, apart from Knebel et al. (2020), weakens the purported conclusions as progression in OA cannot unequivocally be attributed solely to the risk factor (the surgical technique).

Dogs over 15 kg in bodyweight took part in all three studies and in each treatment group dogs were matched for age, weight, and gender to ensure treatment groups are not dissimilar from each other. It is worth noting that in Knebel et al. (2020), dogs over 35 kg were absent. It therefore limits the application of its conclusions in giant breeds, as progression in OA might not be the same between two methods as observed in studied population due to larger forces acting on the articular surface.

Furthermore, in the Moore et al. (2020) cohort study, the TPLO group was nearly four times larger than the TTA group. This contributed to bias towards the TPLO group.. Moreover, the selection of procedure for each participant was determined by surgeon or owner preference, once again another source of bias. The non-random allocation of patients for either of the two treatment groups resulted in uneven representation of patient variables. This might have introduced bias as for instance surgeon’s bias for the TPLO surgical technique might have influenced the results.

Although the Knebel et al. (2020) clinical trial was randomised, patient selection for either procedure was performed ’alternately, in sequence’ rather than using computer software as performed by Livet et al. (2019). The former does not allow equal probability of allocation of treatment to an individual independently of previous assignment. Therefore, allocation bias might have been introduced in dog selection for next treatment. Another point of contention in Knebel et al. (2020) is that dogs with bilateral cruciate disease were compared by selecting the limb with the least signs of OA, thus omitting the effects observed in the contralateral limb. Consequently, dogs showing more progression in OA in both categories have been omitted thus the reported OA progression might have been underestimated. Dogs with bilateral disease should have been excluded from the study.

In Moore et al. (2020), the reviewer was blinded of clinical outcome when assessing follow-up radiographs, whereas in Livet et al. (2019) and Knebel et al. (2020) it was not stated if the investigators were similarly blinded of follow-up results.

A weakness in Livet et al. (2019) is that the owner questionnaire was not validated for assessing OA in dogs. In the Knebel et al. (2020), a validated owner questionnaire was not included in the study which makes collation of evidence with Moore et al. (2020) and Livet et al. (2019) difficult. On the contrary, in Moore et al. (2020) a validated clinical metrology questionnaire demonstrated the outcome in TPLO candidates to be significantly better in patient comfort than its comparison. Yet, the retrospective nature of study increases the risk of recall bias, thus participants might have left out details when reporting.

A deficiency seen in all studies is that no confidence intervals were reported for OA scores, rather means/medians and standard deviation/ranges were tabulated. Had confidence intervals been reported this would have given us more certainty about the true population value, thus increasing study validity. Moreover, in none of the studies were sample size calculations performed to determine appropriate participant numbers required to reach the desired power of the study. A difficulty noticed in comparing the two surgical methods is the inter-surgical variability inherently present with TTA. The TTA technique used in the Knebel et al. (2020) study was MMP, in which the tibial advancement is achieved using a titanium wedge while in Livet et al. (2019) a TTA cage is used. These differences increase variability within the TTA category thus making comparisons difficult.

A limiting factor compounding further ability to compare the evidence between the three studies is that the populations are different. The population in Moore et al. (2020) was young/adult with more senior dogs included in other studies, thus adding another source of variation between studies.

Despite only one study (Moore et al. 2020) claiming a noticeable difference in recorded OA between the two surgeries, presently evidence is scant, with most studies (Knebel et al. 2020 and Moore et al. 2020) reporting less OA advancement after TPLO surgery.

Finally, the studies reviewed have various limitations, namely a lack of control groups in some, a lack of blinding, small sample sizes, absent confidence intervals, presence of confounders, study bias, and short follow-up, all reducing ability to translate this information to clinical practice. In practice recommending TPLO over TTA must be based on other factors (e.g. surgeon’s preference) other than the risk of postoperative OA.  A multi-centre, randomised, controlled, clinical trial with a five-year follow-up comparing both procedures is required to investigate if TPLO results in less OA progression than TTA. Long-term follow-up will enable investigators to determine if the radiographic changes reported here similarly continue to progress in both categories and if a significant difference develops between the observed changes of both categories of procedure over time.

The conclusion of this Knowledge Summary is that there is weak evidence to support superiority of TPLO over TTA in reducing the progression of OA in dogs with cruciate rupture.

Methodology

Search Strategy

 

Exclusion / Inclusion Criteria

 

Search Outcome

 

ORCiD

William Grech: https://orcid.org/0009-0009-6986-1670

Conflict of Interest

The authors declare no conflicts of interest.

References

1. Cox, J.S., Nye, C.E., Schaefer, W.W. & Woodstein, I.J. (1975). The Degenerative Effects of Partial and Total Resection of the Medial Meniscus in Dogs’ Knees. Clinical Orthopaedics and Related Research. 109, 178–183. DOI: https://doi.org/10.1097/00003086-197506000-00026
2. Ertelt, J. & Fehr, M. (2009). Cranial cruciate ligament repair in dogs with and without meniscal lesions treated by different minimally invasive methods. Veterinary and Comparative Orthopaedics and Traumatology. 22(1), 21–26. DOI: https://doi.org/10.3415/VCOT-07-06-0063
3. Knebel, J., Eberle, D., Steigmeier-Raith, S., Reese, S. & Meyer-Lindenberg, A. (2020). Outcome after Tibial Plateau Levelling Osteotomy and Modified Maquet Procedure in Dogs with Cranial Cruciate Ligament Rupture. Veterinary and Comparative Orthopaedics and Traumatology. 33(3), 189–197. DOI: https://doi.org/10.1055/s-0040-1701502
4. Livet, V., Baldinger, A., Viguier, É., Taroni, M., Harel, M., Carozzo, C. & Cachon, T. (2019). Comparison of Outcomes Associated with Tibial Plateau Levelling Osteotomy and a Modified Technique for Tibial Tuberosity Advancement for the Treatment of Cranial Cruciate Ligament Disease in Dogs: A Randomized Clinical Study. Veterinary and Comparative Orthopaedics and Traumatology. 32(4), 314–323. DOI: https://doi.org/10.1055/s-0039-1684050
5. Luther, J. K., Cook, C.R. & Cook, J.L. (2009). Meniscal Release in Cruciate Ligament Intact Stifles Causes Lameness and Medial Compartment Cartilage Pathology in Dogs 12 Weeks Postoperatively. Veterinary Surgery. 38(4), 520–529. DOI: https://doi.org/10.1111/j.1532-950X.2009.00520.x
6. Moore, E. V., Weeren, R. and Paek. M. (2020). Extended long-term radiographic and functional comparison of tibial plateau leveling osteotomy vs tibial tuberosity advancement for cranial cruciate ligament rupture in the dog. Veterinary Surgery. 49(1), 146–154. DOI: https://doi.org/10.1111/vsu.13277
7. Pozzi, A., Litsky, A.S., Field, J., Apelt, D., Meadows, C. & Johnson, K.A. (2008). Pressure distributions on the medial tibial plateau after medial meniscal surgery and tibial plateau levelling osteotomy in dogs. Veterinary and Comparative Orthopaedics and Traumatology. 21(1), 8–14.DOI: https://doi.org/10.3415/VCOT-06-12-0099
8. Rayward, R.M., Thomson, D.G., Davies, J.V., Innes, J.F. & Whitelock, R.G. (2004). Progression of osteoarthritis following TPLO surgery: a prospective radiographic study of 40 dogs. Journal of Small Animal Practice. 45(2), 92–97.DOI: https://doi.org/10.1111/j.1748-5827.2004.tb00209.x

 

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Copyright (c) 2026 William Grech

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