While studies report the outcome of TTA surgery as being considered good to excellent in 90% of patients, complications do remain a risk (Hoffmann et al., 2006a). Some studies have suggested these risks are equivalent to other techniques which involve osteotomy (cutting) of the tibia (Wolf, Scavelli, Hoelzler, Fulcher, & Bastian, 2012).
Potential complications include;
Any surgery carries a small risk of infection. Orthopaedic surgery carries a slightly higher risk because bacteria can stick to the metal implants which makes it difficult for the immune system to reach them. In order to reduce this risk, all dogs receive antibiotics during surgery. If your dog licks their wound after surgery, they can introduce infection.
Fracture or Implant Failure
There are different versions of the TTA procedure but all versions do have a potential risk of fracture of the tibial tuberosity, or the shaft of the tibia itself. This is due to mechanical weakening of the bone at the site of the cut in addition to implant insertion which can further weaken the bone.
Fracture of the tibial tuberosity or shaft of the tibia is a challenging complication to manage but can be treated successfully. The risk of such fractures may be minimised with increased surgeon experience performing TTA (Wolf et al., 2012) and consideration of the anatomical factors which may increase these risks (Rajala-schultz, Bergh, & Johnson, 2008).
In a small number of dogs, the implants which are holding the bone in its new position (screws, ‘wedge’, or staple) can become loose over time. If this happens, excessive movement of the bone segments against one another can delay healing and in the worst-case scenario the plate can break and require replacement. The risks of this complication increase substantially if exercise is not sufficiently restricted following surgery.
Delayed healing of the bone
The bone needs to heal to become strong enough to support your dog’s normal activity. In TTA this is especially important as a ‘space’ has been created to advance the tibial tuberosity.
In some versions of TTA, the space is ‘filled’ by a wedge-shaped spacer, other versions use a cage that fills a portion of the gap. Some surgeons use a bone graft to give additional stimulus to bone healing across the gap. The evidence is that bone graft may speed healing of this site, but not reduce complication risk (Bisgard, Barnhart, Shiroma, Kennedy, & Schertel, 2011)
All dogs heal at slightly different rates and sometimes patience is required. However, insufficient exercise restriction after surgery as well as some underlying health conditions can predispose a dog to slow healing.
Fracture of the tibial tuberosity
Possible suggested aetiologies for the development of post-TTA tibial tuberosity fracture include a reduced thickness of the cut tibial tuberosity, reduced osteotomy contact, placement implants too close to the osteotomy, large preoperative patellar tendon angle, and damage to the region during surgical dissection.
While this complication is a risk with TTA it does appear to generally have a favourable prognosis, although it can result in significant morbidity and in some cases revision surgery may be required (Calvo et al., 2014).
Patellar Tendon Damage/Inflammation
The advancement of the tibia may place additional strain upon the patella tendon and the tendon may also be irritated at the time of surgery. Both of these factors have been suggested to be a cause for patellar tendonitis. The reported risk of this is low in TTA (Wolf et al., 2012).
Subsequent meniscal injury
In up to 5.3-10% of patients treated with TTA procedures, the menisci appear normal at the time of surgery but are later damaged due to continued, mild degrees of joint instability. If this is the case, lameness may persist longer than expected post-surgery, or dogs may seemingly recover before suddenly becoming lame on the leg once more. If this occurs, repeat surgery will be required to inspect the meniscus for damage and cut away any torn portions (Hoffmann et al., 2006a) (Etchepareborde, Brunel, Bollen, & Balligand, 2011).