Surgical Treatment of a Monteggia Fracture (Type I) in an Adult Dog Using Original Fixation of the Prosthesis

Abstract

The purpose of this case report is to report the outcome of a 5-year-old male American Staffordshire Terrier with a type I Monteggia lesion with a complex fracture of the ulna of the right forelimb. The dog was treated with ulnar plating and original pattern TightRope™ fixation around the ulna and plate. At 5 months postoperatively, the dog was lameness-free, with normal activity, a negative Campbell's test and a slight decrease in elbow range of motion. Successful surgical management was achieved with an acceptable functional outcome using a TightRope™ tied around the ulna and locking compression plate.

Keywords

Monteggia lesion - tightrope - dog

Introduction

The Monteggia lesion was initially described by Monteggia in 1814 as a fracture of the ulna accompanied by dislocation of the radial head.[1] In 1964, Bado classified the Monteggia lesion into four distinct types, based on the location of the radial head dislocation. Type I corresponds to an ulnar fracture with an anterior dislocation of the radial head. Type II involves a posterior dislocation of the radial head. Type III is characterized by a lateral dislocation of the radial head. Finally, Type IV, the least common, presents with both ulnar and radial fractures along with anterior or posterior radial head dislocation.

In dogs and cats, Type I is the most common, accounting for 68.6% of Monteggia lesions.[2] It is typically secondary to trauma with the elbow in extension or from a strike to the caudal aspect of the ulna of the weight-bearing limb with the elbow extended.[1] Most ulnar fractures in these cases are complex and located in the proximal diaphysis.[2]

Surgical treatment is recommended to reduce and stabilize the radial head luxation and the ulnar fracture.[2] [3] [4] [5] [6] [7] A retrospective study by Schwarz and Schrader reviewed the treatment of Monteggia lesions in animals and found various techniques employed for ulnar fractures. The most common method involved using a centromedullary nail and cerclage in 44% of cases, followed by plate and screws in 19% of cases. A combination of a centromedullary nail and a tension band was used in 11% of cases. For radial head dislocations, the primary approaches included transfixion of the radius and ulna with pins or screws in 15% of cases and replacement of the annular ligament in 11% of cases.

This case report describes the surgical treatment of a Monteggia lesion (Type I) using the TightRope™ implant in a previously unreported pattern. In this approach, the TightRope™ surrounds both the plate and the ulnar bone rather than being anchored solely through a bone tunnel.

Case Description

A 5-year-old male American Staffordshire Terrier was referred with a Type I Monteggia lesion of the right forelimb and a right ischiatic fracture. The patient was admitted after initial stabilization by the referring veterinarian, which included opioid analgesia (morphine at 0.2 mg/kg) and antibiotic medications prophylaxis (dihydrostreptomycin at 7 mg/kg and benzylpenicillin at 6 mg/kg).

Upon initial assessment, the patient exhibited elbow pain, crepitus, swelling, and a reduced range of motion of the elbow. It also experienced discomfort upon palpation and hip extension of the right hindlimb. Fortunately, there were no neurological deficits detected in either limb.

Radiographs of the right forelimb confirmed a proximal highly comminuted fracture of the ulna, accompanied by a fracture of the medial coronoid process and a craniolateral dislocation of the radial head ([Fig. 1]) corresponding to a Type I Monteggia lesion according to the Bado classification. X-rays of the pelvis revealed a multifragmental fracture with limited displacement of the right ischial tuberosity, which was managed conservatively.

Fig. 1 (A) Orthogonal radiographs of the right forelimb revealing a divergent luxation of the elbow. Mediolateral radiograph of the right elbow showing cranial displacement of the radial head. (B) Orthogonal radiographs of the right forelimb reveal a divergent luxation of the elbow. Craniocaudal radiograph of the right antebrachium revealing lateral displacement of the radial head and humeroulnar luxation and a medial coronoid fracture.

After 48 hours of stabilization, surgical intervention for the Monteggia lesion was carried out. The dog was premedicated with medetomidine (5 μg/kg, intravenous) and morphine (0.1 mg/kg, intravenous). General anesthesia was induced using propofol (2 mg/kg, intravenous) and diazepam (0.25 mg/kg, intravenous) and maintained with isoflurane. A brachial plexus block was performed using bupivacaine. The dog received antibiotic medication prophylaxis with cefazolin (22 mg/kg, intravenous), repeated every 2 hours. Fluid therapy was administered using Ringer's lactate solution at a rate of 3 mL/kg/h, and a constant infusion of fentanyl (2 μg/kg, intravenous) was provided during the surgery.

The dog was positioned in dorsal recumbency for a caudal approach to the elbow. The ulna was exposed surgically from the distal third of the humerus to the center of the antebrachium, revealing extensive muscular damage. Dissection was performed between the radial carpal flexor muscle and the lateral ulnar muscle, providing access to the site of the ulnar fracture. Reduction of the radial head was achieved through external caudal compression and internal traction. Following reduction, a thorough examination of the radial head showed no cartilage damage.

Given the multifragmentary nature of the ulnar fracture, the use of a proximal transfixion pin or screw for stabilization was deemed inappropriate. Instead, a synthetic suture was used for stabilization. A caudo-cranial bone tunnel was created in the radial head using a 2-mm drill, as previously described.[3] An oblong button from a standard TightRope™ (Arthrex Vet Systems and Creekside Blvd, Naples), 3.5 mm, double strand, was inserted through the bone tunnel, reaching the cranial aspect of the radial head.

At this point, the reduction of the ulnar fracture was performed, and a 1.5-mm intramedullary Kirschner pin was inserted in a retrograde manner into the proximal end of the ulna. Following reduction, the Kirschner pin was advanced into the distal end of the ulna. The reduction was then stabilized using a medial 2.7-mm locked compression plate (DePuy Synthes, Johnson & Johnson, Raynham, MA) with four locking screws in each fragment. Each strand of the TightRope™ was then wrapped around the ulna and the locking compression plate (LCP) plate. A round button was tied against the LCP and secured with seven knots on each strand ([Fig. 2]). The stability of the elbow joint was tested in flexion, extension and rotation, and no instability was observed. The surgical field was thoroughly flushed, and muscle, subcutaneous and skin tissues were routinely closed. There was no attempt to remove or stabilize the medial coronoid process during surgery.

Fig. 2 Intraoperative caudal view of the elbow. The TightRope wrapped around the ulna and the LCP pointed by the yellow arrow.

Postoperative radiographs confirmed a good reduction of the ulnar fracture and the radial head dislocation ([Fig. 3]). Postoperative coaptation was applied using an orthotic resin for the first 2 weeks postoperatively, followed by a modified Robert Jones bandage for an additional 2 weeks, with weekly checks. The dog was discharged after 24 hours with oral antibiotic medications, anti-inflammatories, analgesics, and restriction of activity to short leash walks for 2 months. Skin sutures were removed by the attending veterinarian 15 days postoperatively.

Fig. 3 (A) Immediate postoperative radiographs showing elbow luxation reduction. The TightRope system, the centromedullary pin and the LCP plate are seen. Mediolateral radiograph of the left antebrachium. (B) Immediate postoperative radiographs showing elbow luxation reduction. The TightRope system, the centromedullary pin and the LCP plate are seen. Craniocaudal radiograph of the left antebrachium.(C) Schematic representation of the placement of the TightRope system around the ulna and the LCP plate.

Orthopedic and radiographic examinations were scheduled at 4, 8, and 20 weeks postoperatively to monitor overall lameness improvement and, specifically, to assess the clinical impact of the medial coronoid fracture.

At the 4-week follow-up, weight-bearing lameness was observed. Due to financial constraints, the owners chose not to change the external coaptation as recommended on a weekly basis. During the first follow-up visit, irritation related to the dressing was noted on the dog's skin. However, there was no pain response to palpation and mobilization of the elbow, and radiographs showed no evidence of complications.

At 8 weeks postoperatively, the dog displayed subtle lameness in the right forelimb. Palpation of the right elbow revealed reduced range of motion in both flexion and extension compared to the contralateral limb. Radiographs showed no evidence of complications, and although bone healing was evident, it was not yet complete at this stage. A gradual return to activity over the course of 1 month was recommended.

At 5 months postoperatively, the dog remained mildly lame, but the owners reported a complete return to the dog's previous level of activity. During the physical examination, no pain was elicited during Campbell's test. Assessment of elbow range of motion indicated persistent limited flexion at 45 degrees, while full extension was achieved compared to the contralateral elbow. Radiographs revealed healing of the ulna, proper placement of the radial head, and no signs of implant material failure ([Fig. 4]). A radiolucent line was visible around the proximal insertion of the Kirschner pin.

Fig. 4 Five months postoperative mediolateral (A) and craniocaudal (B) antebrachial radiographs showing proper placement of the radial head and no implant failure. Radiolucent line is visible around the proximal insertion of the Kirschner pin. Radiolucent line is visible around the proximal insertion of the Kirschner pin.

Discussion

This case represents the first report of a Type I Monteggia lesion treated with the unique TightRope™ ulnar pattern fixation. Monteggia lesion with complex ulnar fractures accounts for 57% of cases, as reported by Schwarz and Schrader. Several treatment options have been explored, including plate and screw fixation, external fixation, intramedullary pin fixation, or a combination of these techniques.[2] [7] [8] However, due to limited case reports and studies, determining the optimal treatment approach remains a challenge.

Currently, the most common surgical technique involves stabilizing the ulnar fracture with bone plating and a screw, along with stabilizing the radial head dislocation using a caudo-cranial screw.[3]

In an uncomplicated human Monteggia lesion, elbow function can often be restored by addressing the ulnar fracture without primary stabilization of the radial head luxation.[9] However, persistent radial head dislocation may occur in cases of inadequate ulnar stabilization or soft tissue entrapment. In more chronic or complex cases, alternative techniques such as radial head arthroplasty or even radial head excision may be considered.[9] To our knowledge, radial head ostectomy has only been reported in lightweight animals (less than 10 kg).[10] [11]

In this case, the multifragmentary ulnar fracture was managed using a combination of a Kirschner pin and ulnar plating for osteosynthesis. The combination of plate and screw fixation was chosen for stabilization, supplemented by a Kirschner centromedullary pin for reduction and added rigidity. The use of the Kirschner pin may raise questions, however, it was employed to aid in reduction and provide temporary stabilization to facilitate subsequent ulnar plating.

Several methods have been proposed for reducing and stabilizing radial head dislocation. Repairing the torn annular ligament through suturing was previously considered, but it is no longer recommended due to a high recurrence rate.[2] [12] An annular ligament prosthesis has been reported, allowing pronation and supination movements.[4] Additionally, transfixing the radius to the ulna with a pin or screw has been described, but this can interfere with the physiological range of motion of pronation and supination and it requires implant removal, especially in cats.[2] In this case, neither of these techniques was suitable due to the specific configuration of the ulnar fracture.

Until now, the reported use of TightRope™ has included prosthetic replacement of the ligament of the femoral head, the cranial and caudal cruciate ligaments, and collateral and annular ligaments of the elbow.[3] [8] [13] [14] In this case, the multifragmentary ulnar fracture did not allow for ulnar transfixion or initial ligament repair. Therefore, a TightRope™ was used and placed around the previously positioned LCP plate rather than through a bone tunnel, which would have been challenging due to the splintering part of the bone. To the authors' knowledge, this specific technique has not been described previously.

The management of medial coronoid fracture can be a concern. While fragmentation of the medial coronoid process is often associated with dysplasia, traumatic fractures unrelated to dysplasia are relatively uncommon. In cases of dysplasia, the consensus is to remove the fragment through arthroscopy or arthrotomy.

Traumatic coronoid fractures have less standardized management. Such fractures have been reported in association with a Monteggia lesion, and in some cases, conservative management was initially pursued.[15] However, if significant, persistent lameness is present, surgical removal of the coronoid fragment may be warranted. Isolated traumatic fractures of the medial coronoid process have also been reported, with successful outcomes following arthroscopic removal of the fragment.[16] [17] The published literature generally supports surgical management in cases of traumatic coronoid fractures.

In this case, the decision was made not to intervene initially for the traumatic fracture of the medial coronoid process to avoid prolonging operative time and the surgical approach. The owner was informed that surgical removal would be performed if discomfort persisted during follow-up.

At the 5-month follow-up, the dog exhibited a decrease in elbow range of motion, although it did not significantly affect its gait. However, this follow-up duration may be too short to fully assess the development of osteoarthritis.

The most common complications of Monteggia lesion repair include loss of range of motion, osteoarthritis, and recurrent radial head dislocation.[1] [2] Additionally, previous reports with TightRope™ have highlighted its susceptibility to infection and implant fracture, but it did not occur in this case.[14] Despite the decrease in elbow range of motion observed in our case, the 5-month follow-up duration is likely too short to fully evaluate the development of osteoarthritis. Postoperative dislocation of the radial head is a rare complication, typically occurring within the first few weeks after surgery.[2] [18] [19] Given the lack of instability on elbow examination during follow-up, we can assume that our case is currently at a low risk for this complication.

The use of TightRope™ has been shown to provide an alternative approach for Monteggia lesions when a traditional transarticular approach is not feasible.

Conflict of Interest

None declared.

• References

• 1 Bado JL. The Monteggia lesion. Clin Orthop Relat Res 1967; 50 (50) 71-86
• 2 Schwarz PD, Schrader SC. Ulnar fracture and dislocation of the proximal radial epiphysis (Monteggia lesion) in the dog and cat: a review of 28 cases. J Am Vet Med Assoc 1984; 185 (02) 190-194
• 3 Vallone L, Schulz K. Repair of Monteggia fractures using an Arthrex Tightrope system and ulnar plating. Vet Surg 2011; 40 (06) 734-737
• 4 Schreiber K, Rousseau T, Gauthier O, Type II. Monteggia lesion with complete elbow dislocation in a cat. VCOT Open 2022; 5: e30-e35
• 5 Fernandez-Sanchez A, Calvo I, Farrel M. Articular type II Monteggia fracture with concurrent humero-ulnar luxation in a Bengal cat. Vet Rec Case Rep 2019; 7 (01) 7-10
• 6 Irubetagoyena I, Lopez T, Autefage A, Type IV. Type IV Monteggia fracture in a cat. Vet Comp Orthop Traumatol 2011; 24 (06) 483-486
• 7 Anatolitou A, Krystalli AA, Sideri KI, Markou M, Kazakos G, Prassinos NN. A retrospective study of Monteggia fractures in 8 dogs and 1 cat. Top Companion Anim Med 2024; 61: 100889
• 8 Garcia M, Bismuth C, Deroy-Bordenave C. Repair of a divergent elbow dislocation with distal ulnar fracture in a dog using tightrope and external skeletal fixation. VCOT Open 2021; 4: e58-e64
• 9 Kim JM, London DA. Complex Monteggia fractures in the adult cohort: Injury and management. J Am Acad Orthop Surg 2020; 28 (19) e839-e848
• 10 Heidenreich DC, Fourie Y, Barreau P. Presumptive congenital radial head sub-luxation in a shih tzu: successful management by radial head ostectomy. J Small Anim Pract 2015; 56 (10) 626-629
• 11 Verdese P, Manfredini S, Formaggini L. Surgical treatment of congenital radial head luxation in a cat by ostectomy of radial head. VCOT Open 2022; 05 (01) e1-e5
• 12 Boudrieau RJ. Fractures of the radius and ulna. In: Slatter D. ed. Textbook of Small Animal Surgery. 3rd ed. Philadelphia: W.B. Saunders; 2003. :pp. 1955-1973
• 13 Kieves NR, Lotsikas PJ, Schulz KS, Canapp SO. Hip toggle stabilization using the TightRope® system in 17 dogs: Technique and long-term outcome. Vet Surg 2014; 43 (05) 515-522
• 14 Cook JL, Luther JK, Beetem J, Karnes J, Cook CR. Clinical comparison of a novel extracapsular stabilization procedure and tibial plateau leveling osteotomy for treatment of cranial cruciate ligament deficiency in dogs. Vet Surg 2010; 39 (03) 315-323
• 15 Schaeffer IGF, Wolvekamp P, Meij BP. et al. Traumatic luxation of the elbow 31 dogs. Vet Comp Orthop Traumatol 1999; 12: 33-39
• 16 Yovich JC, Read RA. Traumatic fracture of the medial coronoid process in two dogs. Vet Comp Orthop Traumatol 1994; 7: 173-176
• 17 Tan DK, Canapp Jr SO, Leasure CS, Dycus DL, O'Donnell E. Traumatic fracture of the medial coronoid process in 24 dogs. Vet Comp Orthop Traumatol 2016; 29 (04) 325-329
• 18 O'Brien MG, Boudrieau RJ, Clark GN. Traumatic luxation of the cubital joint (elbow) in dogs: 44 cases (1978-1988). J Am Vet Med Assoc 1992; 201 (11) 1760-1765
• 19 Sajik D, Meeson RL, Kulendra N. et al. Multi-centre retrospective study of long-term outcomes following traumatic elbow luxation in 37 dogs. J Small Anim Pract 2016; 57 (08) 422-428

Publication History

Received: 14 September 2024

Accepted: 15 February 2025

Article published online:
04 June 2025