Keywords
carpal valgus - flexural deformity - z-tenotomy
Introduction
Muscle contracture consists of fibrosis of the muscle leading to increased resistance
and inability for the muscle to stretch, which results in a shortened tendon or muscle.[1] Underlying causes include trauma, infectious agents, fracture, compartment syndrome,
primary myopathies or neoplasia.[2] In the case of flexor carpi ulnaris contracture, it is more commonly reported in
puppies aged 6 to 24 weeks.[3]
[4] With flexor carpi ulnaris contracture, a limb deformity develops characterized by
a flexed carpus with inability to extend. In younger animals, it often resolves spontaneously,
but can be treated with carpal support bandages.[4]
[5]
[6] Exact pathogenesis of flexor carpi ulnaris tendon contracture is unknown. Musculotendinous
contractures occur in small animal patients; however, reports in the literature are
scarce.[4]
[5]
[6]
[7]
[8]
[9] This case report provides documentation of a successful tendon lengthening procedure
and correction of carpal valgus for the treatment of flexor carpi ulnaris and superficial
digital flexor tendon contracture.
Clinical Report
History and Timeline
A 1-year-old male neutered Akita with a history of a left medial patellar luxation
(LMPL) corrective surgery presented to Veterinary Specialty Centre of Seattle Surgery
Department for repair of his right medial patellar luxation (RMPL). The previous LMPL
repair had been performed at 10 months of age after presenting for an audible popping
sound and bilateral pelvic limb lameness. A recession trochleoplasty, tibial tuberosity
transposition and lateral imbrication had been performed for surgical correction of
the LMPL. Medical history included being fully vaccinated, and obtained by the owner
as a puppy with no history of medical illness associated with litter mates. Home environment
involved living with one other dog with appropriate flooring and space for activity.
At the time of presentation for the RMPL repair, the owner noticed a recent onset
of left forelimb lameness of 2 weeks duration. On physical examination, the dog had
moderate bilateral carpal valgus and carpal hyperflexion with more severe changes
noted on the left forelimb ([Figs. 1] and [2]). The dog was ambulatory with grade I/IV right hindlimb and left forelimb lameness.
There was a right grade II/IV MPL. Radiographs of the forelimbs were consistent with
physical examination findings (bilateral carpal valgus and hyperflexion) with no evidence
of bone deformity or physeal irregularities. The RMPL was surgically corrected, and
2 weeks postoperatively, the owner noted worsening of the left forelimb lameness.
Orthopaedic examination at that time showed a grade II/IV lameness on left forelimb
and right hindlimb. The left carpal valgus and carpal hyperflexion had worsened over
this time period. The left flexor carpi ulnaris tendon palpated more taut than the
right. Given the physical examination findings, flexor carpi ulnaris contracture was
suspected. It was discussed that muscle fibrosis may be present, leading to inability
of the tendon to stretch, and surgical correction may be needed, which would include
a tenectomy and lengthening of the tendon if indicated. The owner, however, elected
conservative management with external coaptation of the left carpus with a palmar
fiberglass splint, rather than proceeding with surgical correction at that time. One
week after placing the left forelimb splint, the patient presented for a right forelimb
lameness. There were no abnormalities noted on physical examination, aside from previously
noted moderate carpal valgus and carpal hyperflexion. Despite 6 weeks of external
coaptation with the left forelimb splint, no improvement was seen in the flexural
deformity or carpal valgus. Therefore, a left tendon lengthening procedure was performed
1 week following splint removal ([Fig. 3]). A bivalve cast was placed on the left forelimb postoperatively and removed 8 weeks
after surgery. The left forelimb was recovering well 8 weeks post tendon lengthening
with a moderate lameness present after bandage removal ([Fig. 4]). Three days later, the right tendon lengthening procedure was performed. And again,
a bivalve cast was applied. The patient's activity was restricted for 16 weeks total
with instructions to perform short, 5-minute leash-walks three times daily. At 5 weeks
postoperatively, the cast was changed to a splint bandage and then removed 8 weeks
postoperatively ([Figs. 5] and [6]). After bandage removal, the owner was instructed to perform passive range of motion
exercises on each operated limb for 6 weeks.
Fig. 1 Lateral view of carpal valgus exhibited on initial physical examination.
Fig. 2 Frontal view of bilateral carpal valgus with more severity visible in the left forelimb.
Fig. 3 Preoperative view of the left forelimb with extension of the carpus.
Fig. 4 Frontal view of bilateral forelimbs at 8 weeks postoperatively from the left tendon
lengthening procedure.
Fig. 5 Lateral view of bilateral forelimbs at 8 weeks postoperatively from the right tendon
lengthening procedure.
Fig. 6 Frontal view of bilateral forelimbs at 8 weeks postoperatively from the right tendon
lengthening procedure.
Surgery
Surgical release of the flexor carpi ulnaris and superficial digital flexor tendons
was performed in both forelimbs as staged procedures 8 weeks apart. However, the first
procedure for the left forelimb was performed under the same anaesthetic procedure
as a revision surgery for recurrence of RMPL. In regard to the surgical procedures
for the RMPL revision surgery, the bone within the trochlear groove (previous wedge
trochleoplasty) groove was deepened via resection trochleoplasty and was extended
further proximally into the femoral metaphysis. A tibial tuberosity transposition
was performed and was secured with two Steinman pins and a 20 g tension band wire.
The tibial tuberosity was transposed a little further laterally and distally than
previously to correct for patella alta. A medial release was performed using electrocautery.
The joint capsule was closed with 0 polydioxanone in a simple continuous pattern.
A lateral imbrication was performed using 1 polydioxanone in a modified Mayo mattress
pattern on the biceps fascia. Autologous platelet-rich plasma was injected into the
stifle joint (1 mL).
Surgery for the tendons in both forelimbs was otherwise identical: the dog was placed
in dorsal recumbency. A linear incision was made at the caudal aspect of the mid-to-distal
forelimbs directly over the flexor carpi ulnaris tendons. The skin was retracted with
Gelpi retractors, and the flexor tendons was explored. The flexor carpi ulnaris and
superficial digital flexor tendons were palpably tight. A z-tenotomy was performed
via a longitudinal incision of the flexor carpi ulnaris tendon and tenotomy at each
end. A side-to-side anastomosis of the sectioned ends was made using 4–0 Prolene,
thereby lengthening the tendon. The same procedure was performed on the superficial
digital flexor tendon. Thereafter, the carpus could be fully extended manually and
the valgus was significantly improved. Autologous platelet-rich plasma was injected
into the tendons (0.5 mL each) and the carpal joint.[10] The subcutaneous and intradermal layers were infiltrated with 5 mL of liposomal
bupivacaine. The skin was closed routinely. A bivalved cast was applied postoperatively
for 5 weeks ([Figs. 7] and [8]).
Fig. 7 Postoperative lateral view of the left forelimb revealing marked improvement of carpal
valgus.
Fig. 8 Postoperative frontal view of the left forelimb revealing marked improvement of carpal
valgus.
Follow-up
A 6-month follow-up examination revealed no apparent lameness on examination. There
was no recurrence of carpal valgus or flexural deformity. Clinically, there were no
concerns reported by the owner. The owner was contacted 18 months postoperatively
by telephone and reported that the patient had no recurrence of lameness or limb deformity
and had normal activity.
Discussion
The report shows successful surgical management of flexor carpi ulnaris and superficial
digital flexor musculotendinous contracture in one dog. A specific underlying cause
for this particular case could not be determined. However, based on the presentation,
it was likely congenital or developmental in origin and similar to flexural carpal
deformities that occur in young puppies.[4] Specific treatment for muscle or tendon contracture in young dogs includes medical
or surgical management. Generally, juvenile patients have a favourable response to
medical management, which often involves splinting and exercise restriction.[4]
[5]
[6] Pending on the severity or chronicity of the case, as well as initial response to
medical therapy, surgical management may be indicated sooner. As described in this
case, conservative treatment by splinting of the left forelimb was initially attempted.
Since no clinical improvement was seen, surgical correction with z-tenotomy was elected.
The z-tenotomy tendon lengthening procedure is one of the most common techniques.[11] This type of tenotomy involves a longitudinal incision in the affected tendon followed
by a transverse incision at each end of the longitudinal incision. The result of the
incisions makes an elongated Z formation. A suture anastomosis of the tendon ends
is performed as the final step.[11] Other techniques for tendon lengthening include accordion, modified z-tenotomy,
oblique section and sliding and the Lange technique.[11] The z-tenotomy approach was utilized in this case because it allows for appropriate
tendon healing while minimizing soft tissue trauma and preserving blood supply. As
the superficial digital flexor tendon is considered avascular, it relies heavily on
intrinsic blood supply during the healing phases.[3] This type of tenotomy also prevents gap formation,[12]
[13] thereby eliminating formation of scar tissue.[3] Lack of scar tissue optimizes tendon healing due to the decreased strength and higher
incidence of adhesion formation.[14] No surgical complications occurred in this case. Our result suggests that the surgical
correction with z-tenotomy lengthening technique for carpal valgus with flexural deformity
might be preferable over conservative management with splinting.
