Keywords
tarsocrural joint instability - internal fixation - transarticular external skeletal
fixation - cats
Introduction
Tarsocrural joint instabilities (TCI) involve malleolar fractures, collateral ligament
ruptures and shearing injuries.[1]
[2]
[3] Reconstruction of the articular surface, restoration of anatomic joint alignment
and joint stabilization are paramount to optimize outcome and limit the development
of osteoarthritis.[4]
Reduction of malleolar fractures is typically achieved by open reduction and internal
fixation (ORIF) using pins and a tension band wire or a small lag screw.[4]
[5] Treatment modalities for collateral ligament ruptures include open reduction and
internal stabilization using primary ligament suture and/or prosthetic ligament reconstruction,
external coaptation, transarticular external skeletal fixation (TESF) or a combination
of these.[1]
[2]
[3]
[6]
[7]
[8]
Primary ligament suture should be attempted whenever possible.[9] Unfortunately, primary repair is not always feasible particularly when there is
significant soft tissue damage. Prosthetic ligament reconstruction may be used in
these challenging cases to mimic the action of the ligament and ensure joint stability.
An internal splint is created by placing bone anchors, screws with washers or bone
tunnels at the attachment points of the ligament; these implants or tunnels serve
as anchor points for suture materials.[2]
[6]
[8]
[10]
[11]
[12] Clinical use of this technique in veterinary orthopaedics has only been documented
in dogs in limited retrospective studies.[13]
[14] Anatomic specificities in the cat need to be carefully considered when applying
these techniques as cats only have short collateral ligaments consisting of straight
and oblique branches.[12] Correct implant placement is therefore especially challenging in cats due to the
small bone sizes.
In addition, external supplementary support for 4 to 8 weeks after internal repair
has been recommended until collateral structures begin to heal or are replaced by
fibrous tissue.[14] External support may be achieved using external coaptation or TESF.[3]
[7] External coaptation is generally poorly tolerated in cats, often resulting in slippage
of the bandage after shaking and soiling due to the use of litter tray. Sedation is
often needed for bandage changes to reduce stress to the patient, ensure correct bandage
application and guarantee staff safety.[15] In contrast, TESF is well tolerated, allows for earlier weight-bearing and provides
higher mechanical protection of the repaired tarsocrural joint.[16] However, there is no consensus of the necessary length of treatment with an additional
supportive TESF for TCI in cats to obtain definite stability. In two studies of cats
with injuries of the distal tibia, tarsocrural joints, tarsus and metatarsus treated
with TESF alone or ORIF with TESF, median times for frame removal were 46 and 34 days
respectively.[7]
[17] Several reports have documented outcomes of surgical techniques used for the treatment
of TCI in cats.[3]
[5]
[7]
[17] However, heterogeneity in the data reported makes direct comparison difficult.
To date, there is only sparse information available on treatment, complications and
outcome in cats affected by TCI. Therefore, the aim of this study was to report the
outcome of TCI in cats treated with a combined internal repair and temporary TESF
using the Jean-Alphonse Meynard (JAM) system.
Materials and Methods
Medical records of cats presented to the Clinique Vétérinaire Aquivet during the period
from 1st July 2016 to 1st May 2019 with a TCI that had been treated by open reduction
and internal repair with concomitant temporary JAM-TESF were retrospectively reviewed.
Inclusion criteria included patients with TCI, complete medical records, preoperative
radiographs, postoperative radiographs and follow-up radiographs at 4 to 8 weeks.
Collection of data was a minimum of 6 months after surgery ensuring adequate time
for the development of complications.[18] Information collected included signalment, body weight, initiating trauma, type
of TCI (medial, lateral or medial and lateral), other concomitant orthopaedic injuries,
surgical approach, implants used, TESF configuration, time to TESF removal and complications
(intra- and postoperative). Open TCI were graded according to the Gustilo-Anderson
classification scheme.[19]
Surgical Technique
Cats were anaesthetized for surgery according to standard protocols used in our hospital.
Potentiated amoxicillin–clavulanic acid (Augmentin; GlaxoSmithKline, Marly-le-Roi,
France, 20 mg/kg intravenously) or cefazoline (Céfazoline; Mylan S.A.S., Saint-Priest,
France; 20 mg/kg) was administered intravenously at induction and every 90 minutes
thereafter during the procedure. All procedures were performed by a boarded-certified
veterinary surgeon (II or JGG). After routine preparation for aseptic surgery, animals
were positioned in dorsal recumbency.
Open Reduction and Internal Repair
A standard medial or lateral approach, or a combined approach via dorsal skin incision,
of the tarsus as needed was performed. A dorsal approach was used when both medial
and lateral sides were injured. Medial malleolar fractures were reduced and repaired
with Kirschner wires, a small lag screw or a pin and tension band wire. Lateral malleolar
fractures were treated in a similar fashion ([Fig. 1]). Primary repair of the ligament was attempted using a locking loop suture pattern
with monofilament nonabsorbable sutures. Prosthetic ligament repair in form of an
internal splint was performed in all cases with a ruptured collateral ligament using
screws and spiked washers or bone tunnels at the closest attachment points of the
ligament ([Fig. 1]). Braided or monofilament nonabsorbable sutures were used to augment or replace
the damaged ligament. The choice of suture materials was at the discretion of the
surgeon. Sutures were placed in a figure of eight around screws with washers or through
bone tunnels and were tightened at a joint angle of ∼115 to 125 degrees of extension.
Routine wound closure of the surgical approach was performed. Axial alignment was
assessed and successful stabilization of the tarsocrural joint was confirmed by systematic
manipulations of the joint stressed in mediolateral, dorsoplantar and rotary planes.
Fig. 1 Radiographs (A–F) and postoperative photographs (G, H) of a 11-month-old 3.0 kg domestic short hair cat (case 14) admitted with a lateral
malleolar fracture and medial collateral ligament rupture (A, B). First, the fracture was stabilized by open reduction and internal fixation using
two 0.8 mm Kirschner wires (C, D). Then, the medial tibiotarsal compartment was stabilized by internal splinting using
two bone tunnels through the medial malleolus (arrow) and talus as anchor points for
polyethylene suture material (C, D). Note, the talar bone tunnel is not visible on the radiographs. Finally, a temporary
Jean-Alphonse Meynard-transarticular external skeletal fixation was applied. Two full
pins were placed proximal and distal to the tarsocrural joint. Accurate reduction
was obtained, and alignment was restored (C, D). Short-term follow-up radiographs obtained at 48 days postoperatively demonstrated
clinical union of the lateral malleolar fracture (E, F). After removal of the connecting bars, the patient was considered to have satisfactory
stability of the tarsal joint by manual manipulations, allowing for definitive frame
removal (G, H).
JAM-TESF
A JAM external skeletal fixation system, capable of holding fixation pins from 1.5
to 3.0 mm in diameter, was used throughout. External support was provided for 4 to
8 weeks after surgery using a medially placed type Ia or type IIa JAM-TESF.[20] Positive-centrally (for type IIa TESF) or end-threaded (for type Ia TESF) pins were
used and were applied percutaneously in all cases without predrilling. Two or three
pins were placed in the tibia and two or three pins were placed in the tarsal and/or
metatarsal bones. Curved connecting bars were used to reproduce the normal joint standing
angle and were positioned with the bend directly over the center of the head of the
talus. No diagonal bars were used ([Fig. 1]).
Radiographic evaluation was performed immediately after JAM-TESF placement. A protective
bandage was applied for 2 to 3 days to limit postoperative swelling, followed by a
light-weight bandage only around the TESF frame to reduce the risk of self-injury
from sharp pins ([Fig. 2]). Regular bandage changes were performed every 7 to 10 days until frame removal.
Fig. 2 Photographs (A, B) showing a light-weight bandage applied only around the transarticular external skeletal
fixation frame to reduce the risk of self-injury from sharp pins while allowing early
weight-bearing.
Short-Term Follow-Up
Clinical and radiographic follow-up was scheduled at 4 to 8 weeks and thereafter as
required. All patients were reviewed at the author's institution by one of the two
board-certified surgeons (II or JGG) or an experienced surgical resident under their
supervision. The timing of final frame removal was determined by (1) radiological
assessment of fracture union (if indicated) and (2) demonstration of stability of
the tarsocrural joint by manual manipulation after removal of the connecting bars
under sedation. Clinical records were evaluated for the assessment of range of motion,
stability, swelling, crepitus or any signs of discomfort. Radiographs at each time
point were assessed for fracture reduction, evidence of implant migration, bone union
and complications associated with the internal implants or JAM-TESF. Complications
were reported as previously defined by Cook et al as catastrophic, major and minor.[18] Time from surgery to complication was noted, and if > 1 complication occurred in
1 patient, each was considered separately.
Midterm Outcome
Midterm follow-up was assessed by a modified owner-answered telephone questionnaire
([Supplementary Material]) at the time of data collection as previously published.[21] The owners were asked to subjectively grade the outcome of their animal based on
the grading system proposed by Cook et al as ‘full’ (performs all normal activities
that were done prior to surgery), ‘acceptable’ (prior activity level not fully regained
but good quality of life/function) and ‘unacceptable’ (permanent constraint).[18]
Data Analysis
Data were entered into a spreadsheet (Excel, version 1906, Microsoft Corp, Redmond,
Washington. Descriptive statistics were calculated, with median and range reported.
Data frequency in each category was reported.
Results
Fourteen cats met the inclusion criteria ([Table 1]). Median age was 5.5 years (range, 8 months to 15 years) and median bodyweight was
4.7 kg (range, 3.0–8.2 kg). Road traffic accident was the cause of TCI in seven cases.
The remaining seven cases were due to domestic accident (n = 3), unknown trauma (n = 2), dog bite (n = 1) and fall (n = 1). Concomitant orthopaedic injuries were found in three cats and included contralateral
craniodorsal coxofemoral luxation (n = 1), sacroiliac luxation (n = 1) and ilial fracture (n = 1). Median time from trauma to surgery was 2 days (range, 0–7 days). Eleven cats
presented a complete luxation of the tarsocrural joint and three cats a tarsocrural
instability. Eleven cases had concomitant medial and lateral, two had lateral and
one had medial TCI ([Table 1]). Eight cases had a lateral, one a medial and two had concomitant lateral and medial
malleolar fractures. Nine TCI were open, of which six were classified as grade 1,
two as grade 2 and one as grade 3A. Bacterial cultures were performed from three joints.
Enterobacter cloacae was isolated in one case. Bacterial culture failed to yield a positive culture in
the remaining cases.
Table 1
Preoperative and operative patient details
|
Case
|
Signalment
|
Initiating trauma
|
Open TCI (grade)
|
Tarsal injury(instability/luxation)
|
Surgical procedure; implants used
|
JAM-TESF configuration; pin diameter; bar diameter
|
|
1
|
DSH, mn, 2 y
8 mo, 5.6 kg
|
HRI
|
1
|
LMF
MCLR
(luxation)
|
Not applicable*
PLS (Prolene[a] 0) + PLR (Prolene[a] 0; through a MM and talus bone tunnel)
|
Type IIa; TTM (3 + 1 + 2); Pd: 1.5 mm; Bd: 3 mm
|
|
2
|
DSH, mn, 15 y
3 mo, 4.0 kg
|
RTA
|
–
|
LCLR (instability)
|
PLR (Monosyn[b] 2/0 through a LM and calcaneus bone tunnel)
|
Type Ia; TTM (2 + 1 + 1); Pd: 2 mm; Bd: 2 mm
|
|
3
|
DSH, fn, 8 mo, 3.2 kg
|
RTA
|
–
|
MMF
LCLR (luxation)
|
ORIF; Pd: 1.25 mm + 1 mm; Cw: 0.8 mm
PLR (Dafilon[c] 1 through a LM and calcaneus bone tunnel)
|
Type IIa; TTM (3 + 1 + 2); Pd: 1.5 mm; Bd: 2 mm
|
|
4
|
DSH, fn, 6 y
11 mo, 5.0 kg
|
RTA
|
2
|
LMF
MCLR
(luxation)
|
ORIF; Pd: 1 mm +1 mm
PLS (Prolene[a] 2/0) + PLR (Prolene[a] 2/0; around a 2 mm tibial screw with washer and through a talus bone tunnel)
|
Type IIa; TM (2 + 2); Pd: 1.5 mm; Bd: 2 mm
|
|
5
|
DSH, fn, 9 y
7 mo, 4.4 kg
|
Da
|
1
|
MCLR
(luxation)
|
PLR (Prolene[a] 0 around MM and talus 2 mm screws with washers)
|
Type IIa; TM (3 + 2); Pd: 2 mm (tibia), 1.5 mm (metatarsus); Bd: 2 mm
|
|
6
|
DSH, mn, 4 y
1 mo, 7.6 kg
|
RTA
|
3
|
LMF
MCLR
(luxation)
|
ORIF; Pd: 1.0 mm + 1.25 mm
PLR (Dafilon[c] 1 through a MM and talus bone tunnel)
|
Type IIa; TTM (2 + 1 + 1); Pd: 2 mm (tibia), 1.5 mm (tarsus and metatarsus); Bd: 2
mm
|
|
7
|
DSH, fn, 9 y
7 mo, 8.2 kg
|
Da
|
–
|
LCLR
(instability)
|
PLR (Ethibond[d] 3 through a LM and calcaneus bone tunnel)
|
Type IIa; TTM (3 + 1 + 2); Pd 2 mm (tibia), 1.5 mm (talus, calcaneus, metatarsus);
Bd 2 mm
|
|
8
|
DSH, mn, 1 y
11 mo, 5.4 kg
|
RTA
|
2
|
MCLR
LCLR (instability)
|
PLR (Dafilon[c] 1 through a MM and talar bone tunnel)
PLR (Dafilon[c] 1 through a LM and calcaneus bone tunnel)
|
Type IIa; TM (2 + 2); Pd 2 mm (tibia), 1.5 mm (metatarsus); Bd 2 mm
|
|
9
|
DSH, mn, 11 y
2 mo, 6.3 kg
|
Ukn
|
–
|
LMF
MCLR (luxation)
|
ORIF; Pd 1 mm + 1 mm; PLS (Monosyn[b] 2/0)
PLR (Ethibond[d] 3 through a MM and talar bone tunnel)
|
Type IIa; TM (2 + 2); Pd 1.5 mm; Bd 2 mm
|
|
10
|
DSH, fn, 2 y
2 mo, 3.2 kg
|
Db
|
1
|
LMF
MCLR
(luxation)
|
ORIF; Pd 1 mm + 0.8 mm
PLR (Monosyn[b] 1 through a MM and talar bone tunnel)
|
Type IIa; TM (3 + 2); Pd 1.5 mm; Bd 2 mm
|
|
11
|
DSH, mn, 4 y
5.2 kg
|
RTA
|
1
|
LMF
MCLR
(luxation)
|
ORIF; 2 mm screw, Pd 1 mm
PLR (Prolene[a] 2/0 through a MM and talar bone tunnel)
|
Type IIa; TTM (3 + 1 + 1); Pd 1.5 mm; Bd 2 mm
|
|
12
|
DSH, fn, 9 y
1 mo, 3.9 kg
|
Ukn
|
1
|
LMF
MCLR
(luxation)
|
ORIF; 1.5 mm screw + Pd 0.8 mm
PLR (Prolene[a] 2/0 through a MM and central tarsal bone tunnel)
|
Type IIa; TTM (2 + 1 + 1); Pd 1.5 mm; Bd 2 mm
|
|
13
|
DSH, fn, 7 y
6 mo, 3.9 kg
|
Da
|
1
|
MMF
LMF
(luxation)
|
ORIF; Pd 1 mm + 1 mm
ORIF; Pd 1 mm
|
Type IIa; TM (2 + 2); Pd 2 mm (tibia), 1.5 mm (metatarsus); Bd 2 mm
|
|
14
|
DSH, fn, 11 mo, 3.0 kg
|
RTA
|
–
|
LMF
MCLR
(luxation)
|
ORIF; Pd 0.8 mm + 0.8 mm
PLR (Ethibond[d] 3 through a MM and talar bone tunnel)
|
Type IIa; TM (2 + 2); Pd 2 mm (tibia), 1.5 mm (metatarsus); Bd 2 mm
|
Abbreviations: Bd, bar diameter; Da, domestic accident; Db, dog bite DSH, domestic
short-haired cat; fn, female neutered; HRI, high rise injury; JAM-TESF, Jean-Alphonse
Meynard transarticular external skeletal fixation; LCLR, lateral collateral ligament
rupture; LM, lateral malleolus; LMF, lateral malleolar fracture; MCLR, medial collateral
ligament rupture; MM, medial malleolus; MMF, medial malleolar fracture; mn, male neutered;
ORIF, open reduction and internal fixation; Pd, pin diameter; PLR, prosthetic ligament
reconstruction; PLS, primary ligament suture; RTA, road traffic accident; TM, tibio-metatarsal;
TTM, tibio-tarso-metatarsal; Ukn, unknown.
Note: Age in years (y) and months (mo).
*Not reconstructible LMF (complete lateral malleolus abrasion).
a Polypropylene (Prolene, Ethicon, Johnson & Johnson International).
b Polyglyconate (Mononosyn, B. Braun®, Johnson & Johnson International).
c Polyamide (Dafilon, B. Braun, Rubi, Spain).
d Coated polyester (Ethibond EXCEL, Ethicon, Johnson & Johnson International).
Surgical Procedure
Primary ligament suture was performed in three cases. Medial prosthetic ligament reconstruction
was performed in 10 cases by the means of an internal splint using bone tunnels (n = 9) and screws with spiked washers (n = 1). Lateral prosthetic ligament repair was performed in two cases using bone tunnels
exclusively. The TCI was stabilized with a type IIa tibio-tarso-metatarsal JAM-TESF
in 6, a type IIa tibio-metatarsal JAM-TESF in 7 and a type Ia medially placed tibio-tarso-metatarsal
JAM-TESF in 1/14 cats. Implants used for internal repair are reported in [Table 1]. Perioperative complications were noted in 1/14 cats on immediate postoperative
radiographs, consisting of cis-cortex pin tract fracture of one JAM-TESF pin. No revision
surgery was performed in this case.
Short-Term Follow-Up
Clinical Assessment
Median time to follow-up was 47 days (range, 34–67 days). The JAM-TESF frames were
well tolerated in all cats. After removal of the connecting bars under sedation, 10
of 12 patients were considered to have satisfactory stability of the tarsal joint
by manual manipulation, allowing for definitive frame removal. In one cat (case 4),
the tarsal joint was still considered unstable. In another (case 7), the JAM-TESF
was left in place 3 more weeks as a precaution as the cat was severely overweight.
Overall, median time to frame removal was 47 days (34–91 days) ([Table 2]).
Table 2
Short-term follow-up data (4–8 weeks postoperatively) including clinical and radiographic
assessments
|
Case
|
Time for frame removal (d)
|
Clinical assessment of tarsocrural joint stability[a]
|
Radiographic recheck
|
Complications (catastrophic, major, minor); specific comments
|
|
1
|
47
|
NI
|
WNL
|
None
|
|
2
|
41
|
NI
|
WNL
|
MiC; pressure sore due to bandage with resolution by second intention healing
|
|
3
|
47
|
NI
|
WNL with RU of MMF
|
None
|
|
4
|
NA
|
NA
|
NA
|
CC; progressive skin necrosis of the paw with loss of deep pain sensation and subsequent
hind limb amputation on day 15
|
|
5
|
NA
|
NA
|
NA
|
CC; ischemic necrosis of the dorsal metatarsal skin with loss of deep pain sensation
on day 17 and subsequent hindlimb amputation on day 31
|
|
6
|
51
|
PTCI
|
WNL with RU of LMF
|
MaC; wound and implant infection after TESF removal (Enterococcus faecalis), recurrence
of TCI 8 weeks postoperative (implant removal, open wound management; arthrodesis
with modified type II ESF 12 weeks postoperative)
|
|
7
|
91
|
NI
|
Fracture of metatarsus V at the pin-bone interface, intra-operative fractures of the
cis-cortex of tibial pins with mild callus formation,
|
MiC; conservative treatment
|
|
8
|
55
|
NI
|
WNL
|
None
|
|
9
|
67
|
NI
|
WNL with RU of LMF
|
None
|
|
10
|
50
|
NI
|
WNL with RU of LMF
|
None
|
|
11
|
40
|
NI
|
WNL with RU of LMF
|
None
|
|
12
|
34
|
NI
|
RU of LMF, mild bone lysis around LM screw, moderate OA
|
CC; necrosis of phalanges III-V and dorsal metatarsal skin wound 2 weeks postoperatively
treated with phalangeal amputations
|
|
13
|
43
|
NI
|
RU of LMF, osteomyelitis tibia, bone lysis around MM implants
|
MiC; treatment: Cephalexin and modified Robert Jones bandage for 1 week after TESF
removal
|
|
14
|
48
|
NI
|
RU of LMF; mild OA
|
None
|
Abbreviations: CC, catastrophic complication; LM, lateral malleolus; LMF, lateral
malleolar fracture; MaC, major complication; MiC, minor complication; MM, medial malleolus;
MMF, medial malleolar fracture; NA, not applicable; NI, no instability; OA, osteoarthritis;
PTCI, persistent tarsocrural joint instability; RU, radiographic union; TCI, tarsocrural
joint instability; TESF, transarticular external skeletal fixation; WNL, within normal
limits.
a By manual manipulations after removal of TESF bars under sedation.
Complications
Overall postoperative complications occurred in 7/14 (50.0%) cases ([Table 2]). Catastrophic complications were reported in three cats; two cats had extensive
tarsal and digit skin necrosis with loss of deep pain sensation by the 15th and 31th
postoperative day requiring hindlimb amputation (cases 4 and 5); one cat (case 12)
developed skin necrosis on phalanges III to V and was treated by multiple digit amputations.
Major complications occurred in one cat (case 6) with persistent TCI subsequently
treated by pantarsal arthrodesis. All catastrophic and major complications were encountered
with open TCI. Minor complications occurred in three cats including pin tract osteomyelitis
(n = 1), pressure sores due to bandages (n = 1) and fracture of the 5th metatarsal bone (n = 1).
Midterm Outcome
Twelve owners provided questionnaire response during telephone interview at a median
postoperative time of 1 year, 5 months (range, 8 months to 3 years, 7 months) ([Table 3]). Of these, one was of a cat that had been amputated due to severe complications
(case 4) but reported a good quality of life. The remaining 11 owners rated the outcome
as full in five, acceptable in four and unacceptable in two cats. Ongoing lameness
was reported in six cats; four had intermittent lameness and two had permanent lameness.
Table 3
Midterm outcome assessed by owner questionnaire
|
Case
|
Status
|
Follow-up time (y)
|
Ongoing lameness/stiffness
|
Subjective outcome
|
Overall owner satisfaction (satisfied, fair, disappointed)
|
Specific owners' comments
|
|
1
|
Alive
|
3.5
|
N
|
Full
|
Satisfied
|
|
|
2
|
Dead
|
3.4
|
N
|
Full
|
Satisfied
|
|
|
3
|
Alive
|
2.8
|
Y, intermittent
|
Acceptable
|
Satisfied
|
|
|
4
|
Alive
|
2.4
|
NA
|
NA
|
NA
|
Good quality of life although amputated
|
|
7
|
Alive
|
0.8
|
N
|
Acceptable
|
Satisfied
|
Moderate plantigrade stance, severely overweight
|
|
8
|
Alive
|
1.6
|
Y, permanent
|
Unacceptable
|
Disappointed
|
Total plantigrade stance
|
|
9
|
Alive
|
1.4
|
N
|
Full
|
Satisfied
|
|
|
10
|
Alive
|
1.3
|
Y, intermittent
|
Acceptable
|
Satisfied
|
|
|
11
|
Alive
|
1.3
|
N
|
Acceptable
|
Satisfied
|
External rotation of the limb when running
|
|
12
|
Alive
|
0.8
|
Y, permanent
|
Unacceptable
|
Fair
|
Permanent lameness due to multiple phalangeal amputations
|
|
13
|
Alive
|
1.3
|
Y, intermittent
|
Full
|
Satisfied
|
|
|
14
|
Alive
|
0.6
|
Y, intermittent
|
Full
|
Satisfied
|
|
Abbreviations: N, no; NA, not applicable; Y, yes.
Discussion
In this study, the overall outcome following repair of TCI in cats by combining open
reduction and internal repair with temporary JAM-TESF was acceptable. Despite good
initial joint reduction and stabilization, and satisfactory stability of the tarsocrural
joint at short-term in 10/12 patients, persistent lameness at midterm was an important
finding in half of the cases. Nevertheless, midterm outcome was considered as ‘fully
functional or acceptable’ in 10/12 patients and only 2/12 had ‘unacceptable’ function
according to the owners. The JAM-TESF therefore showed to be an adequate means for
adjunct treatment of TCI in cats. It performed favourable when considering necessary
implant stability while being less bulky in our reported light-weight fashion than
other previously published configurations and systems, and therefore offered an improved
comfort to the patient.[1]
[7]
Primary internal repair was used for three purposes: first, to re-establish the congruency
and stability of the joint; second, to maintain good articular reduction before TESF
placement; and third, to mitigate the need for heavy and bulky TESF frames. Internal
repair of the TCI may be particularly challenging due to the complex anatomy of this
region, the small bone sizes and the difficulties to achieve an isometrically placed
prosthesis. In this study, transosseous tunnels were used in most of the cases for
prosthetic ligament reconstruction. This technique has been described to allow more
accurate placement of the prosthetic material at proximal and distal attachment sites
for the collateral ligaments than can be achieved with the use of screws.[6] Furthermore, use of bone tunnels avoids the need for cumbersome orthopaedic implants
especially in cats, which if they are not correctly placed, may cause soft tissue
irritations (i.e. screws with spiked washers), and mechanical conflicts with malleolus
or articular surfaces. Multifilament materials have been considered to induce a high
rate of postoperative infection.[13] However, coated polyester material was used in our study in three cases of closed
TCI without any clear negative impact. Non-absorbable multifilament orthopaedic sutures
are thought to be stronger, stiffer and undergo less elongation than comparably sized
monofilament sutures. Hence, they may be well suited for prosthetic ligament reconstruction.[22]
The type IIa TESF was the most commonly used frame in 13/14 cats. As only one cat
was treated with a type Ia frame, we are unable to recommend whether two pins on either
side of the tarsocrural joint were sufficient. The type IIa TESF provides greater
mechanical stability compared with type Ia and may avoid problems associated with
premature pin loosening.[23] Because type IIa TESF may be bulky in cats, we tried to alleviate as much as possible
our constructs by placing only two pins from either side of the tarsocrural joint
in some cases and by using curved lateral connecting bars without additional triangulation
bars. There remains debate as to the number of pins required proximal and distal to
the tarsocrural joint. Recommendations vary from two to three pins.[7]
[14]
[17] In the study published by Kulendra et al, the number of fixation pins inserted proximally
and distally to the tarsocrural joint respectively varied between 2 + 2 up to 5 + 5,
with the majority of cats having three or more pins on one or both sides of the joint.[17] Due to the limited number of cases, no conclusion could be drawn whether two or
three pins would perform superior over the other. Kulendra et al nevertheless recommended
three pins proximal and distal to the joint in this medially placed type I TESF with
an additional connecting bar (‘A-frame’). Considering the superiority of type II TESF
in cats with TCI,[7] as well as aspects of patient comfort, a type IIa TESF with two pins proximal and
two distal to the joint may be less interfering with walking and normal cat behaviour
while still providing sufficient stability than a medially placed type Ia 3 + 3 A-frame
configuration. Further, using the least number of pins necessary might be advantageous
to avoid compromise of blood supply. Nevertheless, further investigations are needed
to prove these hypotheses.
Predrilling has been recommended for the placement of external fixators.[24] We exempted from this due to the small feline bone size. Based on our study, the
use of two pins proximal and distal to the tarsocrural joint gave good clinical results
and no implant failure was reported in any of the cases. This is in contrast to Kulendra's
report in which a high number of implant-related complications was found when two
pins were used proximal and distal to the tarsocrural joint in type I TESF.[17] In this study, half of the TESF had an additional bar connecting the most proximal
and distal aspect (‘A-frame’).[17] Also, four different TESF systems (IMEX-SK, Kirschner-Ehmer (KE), epoxy putty, IMEX-SK
combined with epoxy putty) were used precluding a direct comparison. Neither the KE
or IMEX-SK clamps nor the JAM clamps have been mechanically tested to date for this
indication. To address these difficulties, only one TESF system has been used in our
study with exclusively positive-threaded pins to improve frame stability as previously
recommended.[25] All clamps used were not reused. We did not report any implant-related complications
with the JAM-TESF, suggesting its suitability for temporary stabilization of TCI in
cats after internal repair. Further investigations are needed for making recommendations
regarding the exact frame type and number of pins necessary for this indication.
The overall complication rate (50%) in this study was comparable to previous reports.[7]
[17] Injuries to the tarsocrural joint are commonly caused by shearing injuries due to
its sparse soft tissue coverage which has been reported in dogs after road traffic
accidents resulting in a combination of injuries to the skin, collateral ligaments
and bony structures.[10] Attention needs to be paid particularly on these open TCI as all catastrophic complications
in our study occurred in this group. Significant differences in wound healing between
species have been found with rates of wound contraction, epithelialization and total
healing being reduced in cats compared with dogs.[26] Given the even thinner skin and the more fragile vascularization in cats, special
attention needs to be paid on the occurrence of complications during the prolonged
healing period.[27] Catastrophic complications were reported in three cats in our study and were all
related to the soft tissues; two cats had extensive tarsal and digit skin necrosis
with loss of deep pain sensation and one cat developed skin necrosis on phalanges
III to V and was treated by multiple digit amputations. Primary soft tissue injury
and additional surgical trauma may impair the fragile vascularization of the distal
limb leading to plantar necrosis as reported in dogs following pantarsal arthrodesis
and in cats after tibial/fibular malleoli fracture repair.[5]
[28] The reasons for necrosis of the paw in case 4 were most likely secondary to the
severity of the initial injury as the viability of the limb was questionable at the
time of surgery. Postoperative complications may have also developed from bandage
application. The reason for necrosis of the digits in case 12 remains unknown, but
bandaging errors could not be ruled out as the cat had been treated by the referring
veterinarian until final frame removal. Bandage-related soft tissue complications
have been reported in up to 63% of cases treated for an orthopaedic condition ranging
from mild erythema to full-thickness skin lesions.[29] A protective bandage was applied after surgery in our cases to limit soft tissue
swelling followed by a light-weight bandage only around the TESF frame ([Fig. 2]) until frame removal to prevent self-trauma from sharp edges of the TESF. In contrast
to external coaptation, the use of TESF with the illustrated protective bandage was
well tolerated in all patients and offered improved comfort. Nevertheless, some surgeons
advise against the use of bandages on external skeletal fixators except for the immediate
postoperative period. Adequate training is needed to prevent bandage injuries.[30]
Persistent or recurrent lameness at midterm in half of the cats as reported by the
owners during questionnaire was an important finding and has not been reported previously.
Considering that 11/14 cats had complete luxations of the tarsocrural joint and 9/14
been open, a poorer outcome can be expected. This is in contrast to the reported excellent
outcome in cats with isolated tibial/fibular malleoli fractures.[5] Unfortunately, the reasons for recurrent or persistent lameness are unknown. Overall,
early recognition and treatment of complications are important as they had a negative
impact on outcome and overall owner satisfaction in our study.
The median time to TESF removal was 47 days in the current study, which is comparable
to the report by Kulendra et al (median, 46 days) but more than reported by Owen et
al (mean, 34 days).[7]
[17] There remains debate regarding the duration of TESF treatment. Decreased synovial
fluid production and range of motion and the initiation of osteoarthritis represent
the most functionally recognizable drawbacks of long-term TESF.[16]
[31]
[32] Based on our study, the decision to immobilize the injured joints for 4 to 8 weeks
was empirical and seemed to be a ‘good’ compromise for achieving sufficient stability
while minimizing deleterious effects.
Limitations of this study are those inherent to its retrospective nature. Due to the
limited number of cases, only descriptive statistics were performed. Minor complications
might have been underdiagnosed as bandage changes were often performed by the referring
veterinarian. Two cases were also lost to follow-up at the time of owner questionnaire
of which one was an amputated cat; however, 11/12 (when excluding the two amputated
cats) have equivalent follow-up as the 32 cases reported by Kulendra et al.[17] Our study has a long midterm follow-up (median, 1.5 years) and further used a clinical
methodology, as per current recommendations. The lack of clinical and radiographic
examination or objective gait assessment such as force plate analysis at mid- and
long-term follow-up represents another limitation. The occurrence and degree of osteoarthritis,
range of motion of the joint or recurrence of joint instability remain therefore unknown.
A recheck was offered for all cats that did not have a full recovery at the time of
owner questionnaire but was declined by the owners. Therefore, the cause of the plantigrade
stance of two cats at midterm follow-up remains unknown. Also, the reason for the
unacceptable function of case 12 is unknown but may be attributed to the multiple
digit amputation rather than the tarsal repair according to the owner. Owner-based
questionnaires have been shown to be a valuable tool for follow-up assessment in dogs,[33] but to the authors' knowledge, no feline questionnaire has been validated.
Conclusion
In conclusion, the use of open reduction and internal repair combined with temporary
JAM-TESF provided an acceptable short- and midterm outcome in the majority of cats.
Recurrent or persistent lameness at midterm remains an important finding in some cases
despite good initial joint reduction, and good joint stability at short-term. Potential
catastrophic complications may develop after surgery including extensive skin necrosis
emphasizing the importance of regular rechecks until TESF removal.
