Pro-stride and extracorporeal shockwave therapy as treatment of lateral collateral desmopathy of the proximal interphalangeal joint in a Dutch Warmblood gelding

Abstract

A 6-year-old chestnut Dutch Warmblood gelding was presented for right front lameness 1 mo after being cast in a stall at a 1.20-meter jumping event. Lameness work-up revealed mild lameness on the right and left front legs, with diffuse swelling over the right front pastern. Ultrasonic evaluation yielded suspicion of collateral desmopathy of the proximal interphalangeal joint that was subsequently confirmed via MRI. Two weeks after initial evaluation, the proximal and distal interphalangeal joints were injected with Pro-Stride Autologous Protein Solution, immediately followed by Extracorporeal Shockwave Therapy of the lateral and medial collateral ligaments. Follow-up at 2 and 3 mo after treatment revealed reduced joint effusion of the proximal and distal interphalangeal joints, as well as improved fiber organization of the associated collateral ligaments.

This should inform practitioners that multimodal therapeutic treatments including biologics and stimulation of healing through sound waves can aid in ligamentous injuries in sport horses.

A 6-year-old chestnut Koninklijk Warmbloed Paardenstamboek Nederland (KWPN) registered Dutch Warmblood gelding active in 1.20-meter jumping was presented for lameness of the right forelimb in late June 2022. One month prior, this gelding had stuck his right front limb in panels in a stall at a horseshow in Langley, British Columbia.

Radiographs conducted by the on-site veterinarian showed no evidence of fractures. The gelding had been rested for 3 wk and on Week 4 when started back into light work, a right front lameness was noted by the client. The horse resided south of Calgary, Alberta.

The gelding was imported from Europe in August 2021. Shod with steel shoes on all 4 limbs, with toe clips on the forelimbs and quarter clips on the hind limbs, the horse had a history of mild effusion bilaterally in the forelimb distal interphalangeal (coffin) joints. He had been treated for a sole abscess in the right forelimb as well as thrush in bilateral front frogs. To help stabilize the heels from the thrush, the horse was shod bilaterally with bar shoes on the forelimbs. The horse had had 2 colic episodes, the latter resulting in a gastroscopy in which Grade 3 non-glandular ulcers and Grade 1 glandular ulcers were diagnosed and treated appropriately. During a soundness examination conducted before the jumper event in May 2022, the gelding was deemed able to proceed with full work.

On physical examination in June 2022, there was notable heat and diffuse swelling over the pastern region of the right forelimb, primarily laterally. Lameness evaluation showed a right front Grade 1 lameness circling to the left and a left front Grade 1 circling to the right on hard ground. On soft ground, there was a right front Grade 2 lameness circling to the left that did not improve with work (1). There were no abnormal findings on flexion tests.

The horse was sedated with 100 mg xylazine (0.2 mg/kg, IV) for ultrasonic evaluation of the right forelimb in the pastern area using a linear transducer (NextGen LOGIQ e Ultrasound with 12L-RS Linear Probe; GE Healthcare, Chicago, Illinois, USA), with a focus on the lateral aspect. This was compared to the contralateral limb. Ultrasonography revealed diffuse subcutaneous thickening over both the lateral and medial pastern of the right forelimb. Joint effusion was noted in the right front proximal interphalangeal (pastern) joint compared to the left front (Figure 1). Bone surfaces appeared normal with no evidence of osteophyte or enthesophyte proliferation. With suspicion of collateral desmopathy, the horse was referred to Moore Equine Veterinary Center Ltd in Calgary, Alberta, for magnetic resonance imaging (MRI) (0.3T standing MRI; Hallmarq Veterinary Imaging, West Chicago, Illinois, USA) of the right fore hoof and pastern. Sequences conducted are outlined in Table 1.

Figure 1.

Ultrasound conducted in June 2022 with a12L-RS Linear Probe. Increased anechoic fluid with hyperechoic swirling present in the right front proximal interphalangeal joint (PIJ) compared to the left front PIJ, indicative of joint effusion.

Table 1.

Magnetic resonance image (MRI) sequences of right forelimb pastern and foot conducted by Moore Equine Veterinary Center Ltd against the planes of sequence slices (dorsal, saggital, and transverse).

	Dorsal	Saggital	Transverse
Pastern	T1 GRE	T1 GRE	T1 GRE
	T2 FSE	T2 FSE	T2 FSE
	T2*W GRE	T2*W GRE	STIR FSE
	STIR FSE	STIR FSE
Foot	T1 3D	T1 3D	T1 3D
	T2 FSE	T2 FSE	T2 FSE
	T2*W GRE	T2*W GRE	STIR FSE
	STIR FSE	STIR FSE

Magnetic resonance imaging revealed marked desmopathy of the lateral collateral ligament (LCL) of the pastern joint (Figures 2, 3 a). A small subchondral bone lesion was evident along the palmar, medial, and distal condyle of the proximal phalanx (P1), contralateral to the LCL injury (Figure 3 b). Mild collateral desmopathy of the coffin joint was evident, with the medial condyle more affected than the lateral (Figure 3 c). Mild oblique sesamoidean desmopathy was present proximally. Moderate effusion/synovitis was present in the coffin joint (Figure 3 d). Lastly, there was mild navicular bone and impar degeneration present with a distomedial navicular bone fragment.

Figure 2.

Magnetic resonance image (MRI) of the right forelimb pastern. a — T2 FSE sequence slice of pastern in dorsal plane with marked desmopathy of the lateral collateral ligament (LCL) outlined by white circle. b — 2 FSE sequence slice of pastern in transverse plane with marked desmopathy of the LCL outlined by white circle.

Figure 3.

Magnetic resonance image (MRI) of the right forelimb pastern and hoof. a — T2 FSE sequence slice of pastern in dorsal plane with marked desmopathy of the lateral collateral ligament (LCL) outlined by white circle. b — T2*W GRE sequence slice of pastern in dorsal plane with subchondral bone lesion of distal condyl of the proximal phalanx (P1) identified by white arrow. c — T2 FSE sequence slice of hoof in dorsal plane with mild collateral desmopathy of the coffin joint, medial (double white arrows) more affected than lateral (singular white arrow). d — T2 FSE sequence slice of hoof in saggital plane with moderate effusion of the coffin joint identified by the white arrow.

In early July 2022, 2 wk after initial ultrasonic evaluation, Pro-Stride Autologous Protein Solution (Pro-Stride APS) was given intra-articularly in the pastern and coffin joints of the right forelimb, followed by extracorporeal shock wave therapy (ESWT). Sedation was induced with 5 mg butorphanol (0.01 mg/kg, IV) and 20 mg xylazine (0.2 mg/kg, IV), plus 2 g phenylbutazone (4.0 mg/kg, IV). An abaxial nerve block was administered to the right front limb using 120 mg (6 mL) mepivacaine (0.24 mg/kg, SC), divided between the lateral and medial aspects.

The left jugular vein was aseptically prepped for blood collection for the Pro-Stride APS. Then, 5 mL anticoagulant citrate dextrose solution A (ACD-A) (ACD-A Solution 10-mL Vial; Strathcona Prescription Center, Edmonton, Alberta, Canada) was sterilely added to a 60-cc syringe and a butterfly catheter primed prior to blood collection via the Pro-Stride APS KIT (Pro-Stride APS 60 mL KIT SINGLE PK; Owl Manor, Warsaw, Indiana, USA). The blood was transferred to the APS Separator Device (Pro-Stride APS 60 mL KIT SINGLE PK), placed in the balanced centrifuge (904003VET-60ML Solid), and centrifuged for 15 min at 3200 RPM. Excess plasma was removed, and the remaining platelet-rich-plasma (PRP) was transferred evenly over the beads into the APS Concentrator Device (Pro-Stride APS 60 mL KIT SINGLE PK). The concentrator was placed in the balanced centrifuge (904002VET-APSCB) and centrifuged for 2 min at 2000 RPM. The final concentrated APS solution was gently resuspended, and the Pro-Stride APS KIT was evenly divided into 2 equal portions. The pastern and coffin joints of the right forelimb were prepped aseptically and injected via the dorsal approach.

Sterile lube was applied along the lateral, dorsal, and medial aspect of the right forelimb. A sterile rectal sleeve was placed over the head of the 20-mm trode (PulseVet ProPulse 20-mm trode (REFURB); Alpharetta, Georgia, USA) for application of the electrohydraulic ESWT (PulseVet ProPulse Electrohydraulic Shock Wave Generation; Alpharetta, Georgia, USA). In total, 250 shocks were delivered per side at energy level 5 (E5) along the lateral and medial pastern, tracking dorsally. Sterile gauze was placed over the injection sites and secured with lightplast. The gelding was confined to a small paddock and instructed to be rested until further evaluation.

At follow-up in August 2022, there was decreased swelling of the right front LCL (Figure 4 a,b). Ultrasonography revealed reduced subcutaneous thickening over both the lateral and medial pastern of the right forelimb as well as reduced effusion in the pastern and coffin joints. An ESWT (PulseVet ProPulse Electrohydraulic Shock Wave Generation) series of 3 treatments at 10-day intervals was implemented. At each treatment day, 500 shocks were delivered at energy level 6 (E6) using a 20-mm trode (PulseVet ProPulse) for the LCL of the right front pastern and medial collateral ligament (MCL) of the coffin joint. In late-September 2022 once the ESWT series had been completed, the patient was clinically sound at a trot. Ultrasound examination revealed reduction of hypoechoic fibers and increased organization of the LCL compared to that in the August evaluation (Figure 5). The patient was then referred to Moore Equine Veterinary Center in Calgary, Alberta, for rehabilitation to slowly load the healing ligament and soft tissue structures in a controlled manner.

Figure 4.

Ultrasound of the right front lateral collateral ligament (LCL) of the proximal interphalangeal joint (PIJ) conducted in August 2022 with a12L-RS Linear Probe. a — Hyperechoic LCL with lack of distended joint capsule. b — Mildly enlarged and disorganized hypoechoic fibers within hyperechoic organized fibers of the LCL.

Figure 5.

Ultrasound of the right front lateral collateral ligament (LCL) of the proximal interphalangeal joint (PIJ) conducted in September 2022 with a12L-RS Linear Probe. Reduction of hypoechoic fibers and increased organization of the LCL.

Discussion

Lameness due to musculoskeletal disease and injury is the most common diagnosis in equine veterinary practice. Many of these orthopedic disorders are chronic problems in which clinically satisfactory treatment does not exist (2). The present case had multiple pathologies including a chronic mild left front lameness, subchondral bone lesion, bone and ligament degeneration, joint effusion in both the pastern and coffin joint, as well as desmopathy of the oblique sesamoidean ligament, the LCL of the pastern, and the medial collateral ligament (MCL) of the coffin joint (2–4).

Collateral ligaments lie along the medial and lateral aspects of the joints and limit the movement of bones to 1 plane. Although uncommon, injuries to the collateral ligaments between the proximal (P1) and middle (P2) phalanx occur in performance horses that repeatedly load or overload these ligaments (5). Stress and tears to the ligaments can occur due to twisting and turning movements, such as in this case. The prognosis for these types of injuries is generally guarded to good, depending on early diagnosis and treatment (5).

Regenerative medicine aims to replace or regenerate cells and tissues to restore normal function. Most regenerative techniques are used to treat desmopathies, tendinopathies, tendon injuries, cartilage injuries, and degenerative joint disorders (6,7). Pro-Stride is a concentrated protein solution used to reduce pain and inflammation in equine joints (8–10). An attractive feature of Pro-Stride is that it can be readily deployed as a stall-side treatment. These commercial kits use filtration and centrifugation to isolate and concentrate platelets and produce the PRP (11,12). Blood is drawn from the horse, platelets and white blood cells (WBCs) are isolated in a small volume of plasma, then desiccating beads further concentrate the naturally occurring proteins (8–10). The proteins include anti-inflammatory cytokines (sTNF-R1, sTNF-R11, IL-1ra, sIL-1R) and anabolic growth factors (IGF-1, HGF, TGF-β1, PDGF-ββ) (10). The release kinetics of transforming growth factor-β1 (TGF-β1) and platelet-derived growth factor ββ (PDGF-ββ) have been most extensively studied and have critical roles in regeneration and healing of damaged tissues (11–14).

Extracorporeal shockwave therapy (ESWT) is another regenerative technique used by equine practitioners. Pulses emitted from the shockwave unit are transmitted into the tissues and stimulate healing of the targeted structure (15). Although its mechanism is not fully understood, it is believed to cause interstitial and extracellular responses leading to tissue regeneration and repair (11,16). Based on ultrasound assessment, ESWT improved the rate of healing of experimentally induced suspensory ligament desmitis in horses (11,17) and improved the prognosis of horses diagnosed with forelimb proximal suspensory desmitis returning to full work by 6 mo (11,18,19).

Applying ESWT to PRP increased concentrations of TGF-β1 and PDGF-ββ released from platelets in vitro (11). Since PRP is a component of Pro-Stride, ESWT was conducted immediately after Pro-Stride injection of the pastern and coffin joints. Our intention was to promote healing of the collateral ligaments and treat effusions in both the pastern and coffin joints. Consecutive follow-up examinations indicated reductions in soft tissue swelling and joint effusion, as well as a return to clinical soundness. As such, the proposed treatment plan with the addition of a 3-part ESWT series was successful in medicating the acute soft tissue injuries for this gelding prior to beginning rehabilitation. This case shows how multimodal regenerative medicine techniques including Pro-Stride and ESWT can be used in performance horses to aid in healing ligamentous injuries.