Synthetic Reconstruction of the Carpal Short Radial Collateral Ligament Following a Partial Sprain Injury in a Dog

Abstract

This study aims to report the clinical presentation, diagnosis, surgical treatment, and follow-up of a chronic traumatic grade 2 sprain of the carpus involving partial rupture of the short radial collateral ligament (SRCL) in a dog. A 5-year-old, 25-kg spayed female crossbreed dog was diagnosed with a traumatic grade 2 sprain injury of the SRCL of the left carpus. Despite carpal splinting for 1 month, persistent lameness warranted surgical reconstruction. It was achieved using a single synthetic ultra-high-molecular-weight polyethylene implant, going from the radius into the intermedioradial bone and around the second metacarpal bone to reconstruct the two strands of the SRCL. The reconstruction was stabilized using interference screws and a cortical button. After 1 month of carpal immobilization with a modified Robert Jones, gradual resumption of activity was initiated. At two postoperative months, only grade 1 lameness was present and progressively resolved. One year after surgery, the dog had regained full function without recurrence of lameness on the operated limb. Reconstruction of the SRCL following a traumatic grade 2 carpal sprain in dogs is possible using a braided ultra-high-molecular-weight polyethylene implant secured with interference screws and a cortical button. Despite secondary ankylosis, this technique avoids the use of salvage procedures such as carpal arthrodesis.

 

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Keywords

collateral ligament - radius - dog - synthetic reconstruction - UHMWPE implant

Introduction

The canine carpus is a complex diarthrodial joint anatomically defined as a hinge joint moving in one plane, also called a ‘ginglymus joint’.[1] [2] It is composed of multiple small bones stacked vertically, creating three joint levels proximally to distally: The antebrachiocarpal, the intercarpal and the carpometacarpal joints, which are responsible for 70%, 25% and 5% of carpal motion, respectively.[1] The main forces on ligamentous support are concentrated at the antebrachiocarpal level. The two rows of carpal bones are held together by small supportive ligaments, and no continuous ligament crosses several joints in the carpus.[1] In dogs, lateral-to-medial stability is provided by collateral ligaments: The short radial collateral ligament (SRCL, composed of two strands) and the short ulnar collateral ligament.[1]

Carpal injuries can be divided into sprains, strains, luxations, fractures or a combination of the latter.[3] Sprains can be further divided into three grades, from simple overstretching without disruption to complete tearing of the ligament.[3] Grade 2 indicates a partial tear of the ligament and associated reduction in its strength. The most common carpal injury in dogs is caused by hyperextension of the joint, causing disruption of the palmar ligaments. The severity of this type of lesion usually leaves few treatment options, and salvage procedures such as partial or total arthrodesis are often performed. However, when less severe carpal damage occurs, such as isolated collateral injuries, only a few surgical options have been described.[4] [5] [6] Although there are no reports of restorative surgical management of traumatic grade 2 sprain of the SRCL of the carpus in dogs, a surgical option has been reported for the reconstruction of the medial tarsal collateral ligament using an ultra-high-molecular-weight polyethylene (UHMWPE) implant fixed by interference screws (IS) and a cortical button.[7]

This article reports the clinical presentation and diagnosis of a chronic traumatic grade 2 sprain of the SRCL in a dog, its reconstructive surgical management with a synthetic implant to preserve joint mobility, and its long-term clinical outcome.

 

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Case Description

Clinical History and Orthopaedic Examination

A 5-year-old, 25-kg spayed female crossbreed dog was referred for grade 2/5 weight-bearing lameness of the left forelimb for 1.5 months after falling from the second floor.[8] No wound was present. The dog had been treated conservatively by a combination of rest, non-steroidal anti-inflammatory drugs and carpal splint for 1 month with no clear improvement before referral.

On orthopaedic examination, the left carpus was swollen and generalized muscle atrophy of the left forelimb was noted. Carpus mobilization was painful, and moderate valgus instability was observed in comparison with the contralateral carpus ([Fig. 1A, B]). Amplitude in flexion was reduced. Chronic partial sprain of the medial compartment collateral ligaments was therefore suspected.

Fig. 1 Valgus mobilization of left carpus (A) and right carpus (B) with corresponding preoperative stress radiographs under anaesthesia. Medial instability of left carpus is evident. Preoperative computed tomography frontal view of left carpus (C), showing signs of arthropathy and multiple enthesophytes. Radiographs and computed tomography showed absence of fractures. Ultrasonographic assessment of short radial collateral ligament (D): The structure is thickened with loss of its fibrillar aspect (white arrow).

 

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Diagnostic Imaging Examination under General Anaesthesia

Although computed tomography (Aquilion 80, Toshiba, France) showed no fracture, swelling of the medial part of the left carpus was observed, with signs of arthropathy and several enthesophytes on the medial side of the joint ([Fig. 1C]). Stress radiographs (Aria HF450, Foschi, France) confirmed the absence of fractures ([Fig. 1A]) and evidenced an opening of the radiocarpal and intercarpal articulations in valgus. Superficial ultrasonography (Aplio A, Canon, United Kingdom) of the medial carpus revealed signs of desmitis of the SRCL ([Fig. 1D]).

These findings indicated a grade 2 sprain of the SRCL with subsequent medial instability. Surgical stabilization of the medial compartment of the left carpus and a salvage pancarpal arthrodesis procedure were both proposed to the owner, who opted for the first option, considering the relatively young age of the dog and her intensive daily activity level. Potential need for pancarpal arthrodesis due to surgical failure or development of osteoarthritis was exposed and accepted by the owner.

 

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Anaesthetic Protocol

The dog was premedicated with medetomidine (5 μg/kg, Dormilan, Axience) and methadone (0.3 mg/kg, Insistor, Axience) before propofol (4 mg/kg, Propomitor, Orion Pharma) induction for general anaesthesia, maintained with isoflurane (Isorane, Axience). Antibiotic medication prophylaxis (20 mg/kg, Cefazoline, Cefazoline Viatris) was administered 45 minutes before skin incision and repeated every 1.5 hours until the end of surgery.

 

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Surgical Treatment

The surgical site was prepared aseptically under anaesthesia. The dog was placed in dorsal recumbency, and the distal left forelimb was draped adequately. An antimicrobial incise drape (3M Ioban, 3M, France) was used to isolate the skin from the surgical wound.

A dorsomedial approach of the left carpus was performed and allowed to confirm the grade 2 injury of the SRCL. Under fluoroscopy, the intermedioradial bone was drilled medially to laterally using a 2.5-mm non-cannulated drill bit ([Fig. 2A]). The radius was then drilled with a 3.6-mm non-cannulated drill bit, starting at the proximal insertion of the SRCL distomedially to proximolaterally. After measuring the depth of the radial tunnel with a gauge, a 3.5 × 11-mm IS ([Fig. 3]) was chosen for implant fixation. This IS was used to compact the tunnel medially to laterally. The same procedure was performed with a 3.0 × 11-mm IS fixed in the intermedioradial bone tunnel. Wire loops were inserted in the two tunnels, and a third one was placed around the base of the second metacarpal bone ([Fig. 2B, C]).

Fig. 2 Intraoperative fluoroscopic craniocaudal views of intermedioradial bone drilling medially to laterally (A) with passage of wire loops (B). Intraoperative photograph of placement of wire loops (C) before ultra-high-molecular-weight polyethylene implant positioning (D). Use of fluoroscopy helped avoid breaching articular surface.

Fig. 3 Implants used for synthetic reconstruction of short radial collateral ligament. Synthetic ultra-high-molecular-weight polyethylene implant composed of two parts: Working section (a) and leader thread sections (b); associated with 3.0 × 11-mm (c) and 3.5 × 11-mm (d) interference screws and cortical button (e). Leader thread sections help insert implant through bone tunnels.

A UHMWPE synthetic implant (Novalig 2000, Novetech Surgery, France; [Fig. 3]) was mounted on an 8.0-mm-diameter cortical button to form two strands. The leader thread sections of the implant were passed through the proximal wire loop, which was pulled laterally to medially to pass the two strands of the implant through the radial tunnel. The implant was blocked laterally by the cortical button. The first strand of the implant was inserted through the intermedioradial bone tunnel using the second wire loop to exit laterally. The second strand was brought distally and passed around the second metacarpal bone with the third wire loop. This strand was then brought back into the radial tunnel with a fourth wire loop (not preplaced) medially to laterally ([Fig. 2B–D]). At this point, the carpus was maintained reduced in a neutral weight-bearing position, and the various strands of the implant were moderately tightened before inserting the two IS into the intermedioradial and radial tunnels medially to laterally ([Fig. 4]).

Fig. 4 Computer-generated craniocaudal (A) and lateromedial (B) images showing position of implants to stabilize carpus: ultra-high-molecular-weight polyethylene implant retained by cortical button laterally. One strand inserted through intermedioradial bone, one around the base of the second metacarpal bone before going back through radial tunnel. Each strand is secured with one interference screw.

Manipulation of the carpus in valgus indicated a stable joint associated with a slight diminution of carpal amplitude in flexion. Despite this reduced amplitude, which was already present before surgery, mobilization was satisfactory in all directions. The extremities of the UHMWPE implants exiting laterally to the bone tunnels were cut flush to the bones. The wound was rinsed, and the approach was closed conventionally in three layers.

Postoperative radiographs showed appropriate carpal reduction and position of the IS and cortical button ([Fig. 5A, B]).

Fig. 5 Craniocaudal and mediolateral radiographic views of operated carpus immediately postoperatively (A, B), at 2-month follow-up (C, D), and at 1-year follow-up (E, F). Position of implants is appropriate, and only progressive evolution of medial osteoarthritis is visible. (G) Front picture of the two limbs when dog is sitting (left) and standing (right) at 1 year postoperatively, showing similar alignment of the operated joint compared to the contralateral limb.

 

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Postoperative Management

The dog was hospitalized for 24 hours before discharge, with a prescription of antibiotic medications (20 mg/kg, Cefalexine, Therios, Ceva) and non-steroidal anti-inflammatory drug (0.1 mg/kg, Meloxicam, Melosus, Axience). A bivalve cast was preformed on its forelimb and used as a modified Robert Jones bandage for 6 weeks, with a change every week. Strict activity restriction was recommended for 8 weeks.

 

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Follow-up

At the 1-month follow-up, manipulation of the joint was pain-free with a marked decrease in the range of motion, possibly due to the immobilization of the limb. Radiographic control showed only a small evolution of periosteal reaction, suggestive of a discrete osteoarthritic progression. C-reactive protein was normal, suggesting the absence of infection. The Robert Jones bandage was kept for two more weeks without the bivalve cast.

At the 2-month follow-up, the dog had recovered with limited activity for only 2 weeks and was already using the limb appropriately despite 1/5 lameness. Although marked swelling on the medial carpus was observed, the carpus was stable in valgus, and its mobilization was painless. Radiographic control showed no complications ([Fig. 5C, D]).

Gradual resumption of activity over 4 months was decided with a progressive increase of walking time for the first 2 months, followed by trot exercises, always on a leash, for the next 2 months. Six months after surgery, the owner reported normal gait and a return to the same activity level as before the surgery. One year after surgery, the clinical orthopaedic examination showed a normal gait with no lameness. The carpal range of motion was measured from 105 degrees in flexion to 195 degrees in extension without any sign of pain. Radiographic control showed good stability of the implants and moderate progression of medial joint osteoarthritis ([Fig. 5E, F]). Alignment of the operated joint was similar to the contralateral joint ([Fig. 5G]).

 

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Discussion

Traumatic grade 2 sprain of the SRCL of the carpus was diagnosed in a 5-year-old, 25-kg spayed female crossbreed dog by a focused orthopaedic examination and a combination of diagnostic imaging techniques. Surgical reconstruction was mandatory as the dog did not respond to conservative treatment. It yielded good results characterized by a stable joint and a normal gait 1 year after surgery, despite a decreased amplitude in flexion evaluated at 105 degrees at last follow-up.

Isolated carpal ligament injury is an uncommon condition in dogs that generally suffer a multiple ligament injury following a traumatic event.[1] [9] Pancarpal arthrodesis is often chosen whenever the antebrachiocarpal joint is injured, especially after a hyperextension injury.[3] [10] In the present case, only a grade 2 sprain injury of the medial collateral ligaments was diagnosed, so we ought to find an alternative treatment to arthrodesis in order to maintain joint integrity and avoid postoperative complications.[11] While successful, this technique would not have been an option if a concomitant palmar ligament rupture had been present. It also carried a risk for subsequent revision surgery with pancarpal arthrodesis in case of reconstruction failure or development of debilitating osteoarthritis. Isolated medial ligament injuries have been reported previously, mostly in racing Greyhounds.[5] [6] [12] Although the exact cause of this type of injury is unknown, an ex vivo study highlighted the weakness of the collateral ligaments compared to other carpal ligaments.[13] However, the reason for the predominance of medial injuries over lateral ones remains elusive.

Grade 2 sprain of the SRCL is less often reported than grade 3, which causes marked instability or even subluxation of the joint.[4] [5] [9] [14] [15] Here, the dog had a permanent, discrete lameness caused by moderate instability of the carpus. Mobilization and radiographic projections in valgus suggested a ligament injury, which was further confirmed by ultrasonography. Ultrasound of the carpal joint is not widely used in routine practice. However, medial and lateral collateral ligament evaluation was reported recently in healthy dogs.[16] In our case, the signs of desmitis identified by ultrasonography suggested a grade 2 sprain injury of the short radial ligament, which explains the moderate instability observed at the clinical and radiographic examinations. Ultrasonography may therefore be a reliable tool to diagnose carpal ligament injury in dogs. In humans, magnetic resonance imaging remains the main imaging modality to diagnose wrist joint abnormalities.[17] Although its use in small animals is scarce, it may be helpful in characterizing ligament injuries following trauma in dogs.

Carpal brace application has been reported as a viable option to treat ligament injury in dogs, with a significant reduction in valgus and improvement of flexion upon removal of the brace.[2] Unfortunately, no clear data are available regarding the duration of brace application to improve carpal movement. However, since the application of a carpal splint for 1 month did not improve lameness, surgical treatment was mandatory. The surgery aimed to stabilize the carpus with a single synthetic implant. Several types of implants have been used on distal articulations, including orthopaedic wire, nylon monofilament and UHMWPE implants.[4] [5] [7] [18] UHMWPE implants showed satisfactory ex vivo results in terms of pullout strength and intrinsic resistance when used for canine cranial cruciate ligament reconstruction.[19] [20] Moreover, their use for tarsal and carpal ligament reconstruction was successful in several reports of closed injuries, justifying our choice for this case.[5] [7] The fixation method of the implant is as important as the mechanical properties of the implant itself to neutralize joint instability. Inappropriate fixation would result in instability recurrence. The use of bone tunnels, bone anchors and IS has already been described.[19] [20] Titanium IS were preferred because they demonstrated adequate strength when used with a UHMWPE implant.[20] Both UHMWPE and titanium also present the advantage of being biocompatible. Another advantage of this system is that the metallic components of the fixation system are buried in the bone tunnels, so there is a lower risk of soft tissue irritation or superficial wound in a distal articulation, such as the carpus.

Anatomically, there is no long ligament located medially in the carpus of dogs, unlike the tarsus.[1] The ideal way to reconstruct the two strands of radial collateral ligaments anatomically would have been to use the double strands of the implant going from the intermedioradial bone to the radius proximally and towards the second metacarpal bone distally, respectively. Unfortunately, although the dog was a medium-sized breed, its intermedioradial bone was not wide enough and presented a risk of fracture if a double-stranded implant combined with an IS had been inserted. To limit the risk of fracture, fluoroscopic views allow for properly underlining the bone contours when drilling and avoid damaging other structures.

The whole articulation from radius to metacarpal bones was not spanned entirely as in Pinna and colleagues, since the greatest instability was observed at the antebrachiocarpal level, where most forces are exerted.[5] We chose not to rely on several metacarpal bones to maintain the implant, as many displacements occur naturally between these bones and may promote implant loosening.[5] The use of a double-stranded implant inserted alternatively in the intermedioradial bone and around the second metacarpal bone was inspired by a previous description of tarsal ligament reconstruction and provided good long-term stabilization of the medial compartment of the carpus, likely completed with fibrosis.[7] Nevertheless, the holding of the synthetic implant between the proximal metacarpal bones relies on the integrity of the ligaments that are holding the bones together. This may be a weakness for this surgical repair if ligament integrity is impaired. The impact of such non-anatomical reconstruction over the years is still to be determined. Particularly, osteoarthritic changes observed at 1-year follow-up may have been precipitated by the long strand of the synthetic implant. It is clear that ligamentous augmentation as well as postoperative fibrosis have contributed to a marked decrease in amplitude in flexion, although the position of the carpus at stance (i.e., in extension) remains the most important element. It is also possible that osteoarthritis continues to develop and requires another treatment, notably a salvage procedure like pancarpal arthrodesis.

No short- or long-term complications were observed. Two factors may have limited the risk of complications: (1) The absence of wound, and (2) the use of external coaptation rather than an external transarticular fixator, which is usually associated with a high complication rate.[21] [22] However, soft tissue injuries remain frequent after external coaptation.[23] A frequent change of bandage and monitoring of the surgical wound may limit complications.

One limitation of this study is the application of a surgical technique in an isolated case with a specific indication, since external trauma rarely causes isolated carpal collateral ligament rupture in dogs. Another limitation is the subjective orthopaedic examination performed during the follow-up. A measure of ground reaction forces via kinetic gait analysis may have provided a better understanding of the dog's recovery.

 

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Conclusion

Reconstruction of a canine SRCL following a traumatic grade 2 sprain was successful using a braided UHMWPE implant secured with IS and a cortical button. The surgical technique is promising for the treatment of cases with isolated ligament injury that do not involve the palmar aspect of the joint. Multiple diagnostic imaging tools should be used to identify the torn ligaments precisely. Although most forces are exerted at the antebrachiocarpal joint, marked instability at this level should not prevent ligament reconstruction.

 

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Conflict of Interest

A.C. and B.G. are employed by Novetech Surgery.

Acknowledgments

The authors thank J. Fritz, Dip. ECVDI, for his help in diagnostic imaging interpretation.

Consent

Owner consent was obtained.

Authors' Contributions

B.D. and B.G. designed the study. B.D. and P.d.G. examined the dogs, diagnosed the pathology, performed the surgery, and carried out follow-up visits. B.D. and P.d.G. collected the data. B.D., P.d.G., A.C., and B.G. analysed and interpreted the data, and wrote, reviewed, and edited the manuscript.

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Publication History

Received: 08 March 2025

Accepted: 05 June 2025

Article published online:
03 July 2025