Background
fig. 1 - postoperative radiograph of a standard TTA
Tibial tuberosity advancement (TTA) is a well-established alternative to tibial plateau levelling osteotomy (TPLO) for neutralising cranial thrust in cruciate deficient canine stifles. This principle was first developed in the early 1960’s by a Belgian human orthopaedic surgeon – named Maquet – to relieve pain associated with chondromalacia of the patella. It was noted at that time that it had the added advantage of reducing shear stress associated with failure of the anterior cruciate ligament. In comparison to other methods of cruciate surgery, TTA has the major advantage over TPLO of not having to section the weight-bearing axis of the tibia which minimises complications resulting from delayed/ non-union or implant loosening. In addition, TTA preserves the physiological femoro-tibial contact pattern to a greater extent as compared to TPLO1.
Back in the 1960’s TTA fell from favour in the human field due to a relatively high rate of fixation failure. In addition, with the advent of mini-skirts female patients deemed the protrusion of their proximal tibias as an unacceptable cosmetic result, despite a good functional outcome.
TTA was re-evaluated for use in canine cruciate disease some 30 years later with the development of specific titanium implants for the veterinary market (see fig. 1). Published results compare favourably with other techniques2,3,4,5,6,7,8,9,10. Downs Veterinary Referrals has offered TTA for the management of cruciate ligament disease for over three years with good results and a low complication rate. However, although well-engineered in their current form, TTA are time-consuming and the implants and exogenous bone-graft required are relatively expensive.
So what is the Modified Maquet Procedure?
fig. 2 - Lateral postoperative radiograph of the MMP.
The Modified Maquet Procedure (MMP) is merely a more robust and simplified version of TTA surgery, relying on a novel implant material, Orthofoam, supplied as a pre-formed wedge which is used to advance and fix the tibial tuberosity, thus replacing the cage, fork and plate in current usage (see fig. 2).
fig. 3 - pre-formed Orthofoam wedges come in a range of sizes, depending on the degree of advancement required.
Orthofoam consists of sintered titanium beads formed into a rigid, porous structure through which new bone can grow (fig. 3; click to enlarge). It can be pre-formed into any shape and provides a non-compressible scaffold to fill the bone void left by conventional TTA. In addition, Orthofoam’s inherently high coefficient of friction helps lock the wedge into position immediately. The associated saw guide also helps achieve accurate, consistent and reliable results. Moreover, rapid bone in-growth results in a robust construct within a few weeks of surgery. This in turn allows for an early return to full weight-bearing and facilitates intensive physiotherapy much earlier than with other techniques.
A further refinement of the MMP is the method of tibial advancement estimation. This relies on datum points located exclusively on the tibia, thus avoiding the necessity to radiograph the limb in 135˚ of flexion as directed previously; a difficult task to reproduce consistently (see fig. 4).
fig. 4 - estimation of advancement relies on tibial datum points only; there is no necessity to position the limb in 135˚of flexion—an inherently imprecise manoeuvre
Without the necessity to apply a plate, fork, cage and graft to the bone, morbidity and surgical time is greatly reduced, aiding the speed of recovery, reducing the cost to the client and most importantly, lowering the risk of complications for the patient and speeding their recovery.
Don’t hesitate to contact us if you would like any further information on this technique or think you may have a suitable case—prices start at around £1500 incl. for assessment, surgery and follow-up.
References
1. Kim SE, Pozzi A et al. Effect of tibial tuberosity advancement on femoro-tibial contact mechanics and stifle kinematics. Vet Surg. 2009; 38 (1)33:39.
2. Hoffmann DE, Miller JM et al. Tibial tuberosity advancement in 65 canine stifles. Vet Comp Orthop Traumatol. 2006;19(4):219-27.
3. Lafaver S, Miller NA et al. Tibial tuberosity advancement for stabilisation of the canine cranial cruciate ligament-deficient stifle joint: surgical technique, early results, and complications in 101 dogs. Vet Surg. 2007;36(6):573-86.
4. Kim SE, Pozzi A et al. Tibial osteotomies for cranial cruciate ligament insufficiency in dogs. Vet Surg. 2008;37(2):111-25.
5. Voss K, Damur DM et al. Force plate gait analysis to assess lib function after tibial tuberosity advancement in dogs with cranial cruciate ligament disease. Vet Comp Orthop Traumatol. 2008;21(3):243-9.
6. Stein S, Schmoekel H. Short-term and eight to 12 months results of a tibial tuberosity advancement as treatment of canine cranial cruciate ligament damage. J Small Anim Pract. 2008;49(8):398-404.
7. Boudrieau RJ. Tibial plateau levelling osteotomy or tibial tuberosity advancement? Vet Surg. 2009;38(1):1-22.
8. Kim SE, Pozzi A et al. Effect of cranial cruciate ligament deficiency, tibial plateau levelling osteotomy, and tibial tuberosity advancement on contact mechanics and alignment of the stifle in flexion. Vet Surg. 2010;39(3):363-70.
9. Dymond NL, Goldsmid SE, Simpson DJ. Tibial tuberosity advancement in 92 canine stifles: initial results, clinical outcome and owner evaluation. Aust Vet J. 2010:88(10):381-5.
10. Etchepareborde S, Brunel L et al. Preliminary experience of a modified Maquet technique for repair of cranial cruciate ligament rupture in dogs. Vet Comp Orthop Traumatol. 2011:24(3):223-7.
