The effect of compacted cancellous bone grafting on the healing of subchondral bone defects of the medial femoral condyle in horses

A novel transcoronal surgical technique for the treatment of cystic lesions of the distal phalanx: A cadaveric study

OBJECTIVE

To assess the feasibility of a novel transcoronal approach for the treatment of axial type 3 cysts of the palmar/plantar aspect of the distal phalanx (P3).

STUDY DESIGN

Ex vivo, experimental study.

SAMPLE POPULATION

Ten cadaveric specimens, four forelimbs and six hindlimbs.

METHODS

All cadaveric specimens underwent radiographically guided drilling, followed by cortical screw placement. The cartilage was macroscopically assessed after disarticulation of the distal interphalangeal joint. The entry point and trajectory were evaluated with computed tomography. Results were categorized as: axial, near-axial and abaxial. The minimal distance from the outer margin of the drill hole and the proximal border of the subchondral bone plate was measured using frontal computed tomographic slices.

RESULTS

Eight of the 10 screws were in an axial to near-axial position and nine followed the desired axial to near-axial trajectory. One screw was inserted axially but continued in an abaxial trajectory. Iatrogenic damage to the joint cartilage, flexor cortex and solar canal of P3 was not observed. All cortical screws were placed close to the proximal subchondral bone-plate of P3.

CONCLUSION

The desired axial/near-axial drilling and screw placement, under radiographic guidance, was achieved in nine out of 10 specimens.

CLINICAL SIGNIFICANCE

This novel technique seems promising for the treatment of inaccessible P3 cysts. Additional studies are required to investigate its feasibility in clinical cases, and the long-term outcome following transcystic screw placement of type 3 P3 cysts.

Treatment Comparison for Medial Femoral Condyle Subchondral Cystic Lesions and Prognosis in Yearling Thoroughbred Racehorse Prospects

Subchondral cystic lesions (SCL) in the medial femoral condyle are a usual finding in Thoroughbred survey and auction repository radiographs. Several treatments with different outcomes have been studied over the years to improve soundness and racing prognosis. Our objective was to report the racing prognosis in Thoroughbred yearlings intended for racing that were diagnosed with SCL in the medial femoral condyle and were treated using four current and different techniques: intralesional injection of corticosteroids, SCL debridement through the joint with a drill bit, translesional cortical screw placement, and absorbable hydroxyapatite implant placement. Data from 182 Thoroughbred yearlings treated for SCL in the medial femoral condyle were collected from 2014 to 2020. Limb affected, age at surgery, sex, and radiographic measurements of the SCL were recorded. Auction price and racing performance were collected for treated horses and compared to 154 maternal siblings free of medial femoral condyle SCL. Analyses were conducted to assess if racing prognosis was affected by SCL size, to detect differences in auction price and selected flat racing outcome parameters between cases and controls, and to compare racing prognosis between the studied treatments. Mares and lesions located in the right stifle were significantly overrepresented. The auction price of treated horses was significantly lower than that of their siblings. Horses treated for SCL had significantly lower chances to start in a race than controls (59% vs. 74% respectively). Wider SCL negatively affected the chances to start at least in one race, and negatively affected the earnings made in the 2-year-olds' racing year. Horses with SCL treated using a bioabsorbable implant had a significantly higher median in starts as 3-year-olds (seven starts) than horses that had the SCL debrided with a drill bit (three starts). In conclusion, Thoroughbred yearlings treated for a medial femoral condyle SCL had lower auction prices and decreased ability to start a race compared to siblings' wider cysts had worse prognosis to start a race and might affect earnings as 2-year-olds; and horses treated with bioabsorbable composite implant placement had more starts as 3-year-olds than with other techniques.

Equine subchondral lucencies: Knowledge from the medial femoral condyle

Equine subchondral lucencies (SCL) have been described since the first availability of suitable radiographic equipment. The initial clinical sign can be lameness, but SCLs are often first found on surveys of juvenile horses and are primarily a radiographic concern for public auctions. When lameness is present, it varies from subtle to obvious and can be intermittent. Some SCLs heal spontaneously, and some remain blemishes, but when the SCL and lameness are persistent, further damage to the joint and limitations to an athletic career are likely. SCLs were initially described in the distal limb followed by the stifle, and the medial femoral condyle (MFC) is now considered the most common location. The aim of this review is to highlight the initial pathology and discuss the clinical and experimental information available on equine SCLs. SCL treatment has evolved from rest alone and has progressed to debridement, grafting, intralesional injection, and most recently, transcondylar screw and absorbable implant placement. Comparison of success rates between techniques is difficult due to variations in follow-up and outcome measures, and no single technique is best for all SCLs. Treatment appears to increase success by 15%-20% over rest alone, but the method chosen depends on many factors. This review emphasizes the need for further work to fully understand SCL formation and all aspects of trabecular bone healing to optimize surgical therapy and improve treatment success.

Treatments and Prognosis for Subchondral Cystic Lesions in the Distal Extremities in Thoroughbred Prospect Racehorses

Subchondral cystic lesions (SCLs) in equines and their treatments have been mainly studied in the medial femoral condyle of the femur. SCLs in the distal extremities affecting the fetlock or interphalangeal joints are frequent, but treatment or prognosis studies in horses are currently sparse. Our objective was to compare four treatments for SCLs in the distal extremities (intralesional injection of corticosteroids, transcortical drilling, cortical screw placement, and absorbable hydroxyapatite implant placement) and report the racing prognoses for affected thoroughbred yearlings. Data from 113 thoroughbred yearlings treated for SCLs in the distal extremities were collected from 2014 to 2020. Age at surgery, sex, bone affected, radiographic SCL measurements, SCL shape, and type of treatment were recorded. Sale data and racing performance were collected for the operated horses and for 109 maternal siblings that were free of SCLs. An analysis was conducted to assess if SCL size affected racing prognosis and to detect differences in sale value and selected racing parameters between the cases and controls. The outcomes for the different treatments, the different bones affected, and the SCL shape type were also analyzed. There was no difference in the ability to start in a race between the cases and controls (60.2% vs. 69.7%, respectively). The auction value of the treated horses was significantly lower than that of their siblings. The bone affected did not impact any of the racing variables studied, whereas the height of the SCLs negatively affected the number of wins and placed races. The type of treatment for the horses affected by SCLs did not have an impact on sale prices, ability to start a race, race starts, wins, and places, or age at the time of the first start. In conclusion, yearlings diagnosed with an SCL in the distal extremities had lower auction prices and decreased racing performances, with lower numbers of wins correlated with larger SCL heights compared to the siblings. Similar racing performance was found regardless of the treatment received.

Osteochondral regeneration of the femoral medial condyle by using a scaffold-free 3D construct of synovial membrane-derived mesenchymal stem cells in horses

Background

Medical interventions for subchondral bone cysts in horses have been extensively studied. This study investigated the regeneration of articular cartilage and subchondral bone with scaffold-free three-dimensional (3D) constructs of equine synovial membrane-derived mesenchymal stem cells (SM-MSCs) isolated from three ponies and expanded until over 1.0 × 107 cells at passage 2 (P2).

Results

SM-MSCs were strongly positive for CD11a/CD18, CD44, and major histocompatibility complex (MHC) class I; moderately positive for CD90, CD105, and MHC class II; and negative for CD34 and CD45 on flow cytometry and differentiated into osteogenic, chondrogenic, and adipogenic lineages in the tri-lineage differentiation assay. After culturing SM-MSCs until P3, we prepared a construct (diameter, 6.3 mm; height, 5.0 mm) comprising approximately 1920 spheroids containing 3.0 × 104 cells each. This construct was confirmed to be positive for type I collagen and negative for type II collagen, Alcian blue, and Safranin-O upon histological analysis and was subsequently implanted into an osteochondral defect (diameter, 6.8 mm; depth, 5.0 mm) at the right femoral medial condyle. The contralateral (left femoral) defect served as the control. At 3 and 6 months after surgery, the radiolucent volume (RV, mm3) of the defects was calculated based on multiplanar reconstruction of computed tomography (CT) images. Magnetic resonance (MR) images were evaluated using a modified two-dimensional MR observation of cartilage repair tissue (MOCART) grading system, while macroscopic (gross) and microscopic histological characteristics were scored according to the International Cartilage Repair Society (ICRS) scale. Compared to the control sites, the implanted defects showed lower RV percentages, better total MOCART scores, higher average gross scores, and higher average histological scores.

Conclusions

Implantation of a scaffold-free 3D-construct of SM-MSCs into an osteochondral defect could regenerate the original structure of the cartilage and subchondral bone over 6 months post-surgery in horses, indicating the potential of this technique in treating equine subchondral bone cysts.

Modified Proximal Interphalangeal Joint Arthrodesis in a Yearling Filly with an Osseous Cyst-Like Lesion in the Proximal Phalanx

After the medial femoral condyle (MFC), the phalanges are the second most common site for osseous cyst-like lesions (OCLLs). Conservative treatment of phalangeal cysts on the convex surface of proximal phalanx presents a technical problem with access to the stoma of the cyst. Surgical therapy options usually aim to avoid cyst enlargement through drilling or screw placement or to encourage lesion filling with osteoconductive material. This paper describes a case of treatment of the OCLL in a yearling Czech warmblood filly with surgical arthrodesis, together with the packing of the OCLL with calcium phosphate biocement (CPB). The filly showed a chronic, moderate to severe, intermittent left hindlimb lameness. Dynamic examination combined with regional anesthesia and radiography confirmed a clinically significant large OCLL on the distal joint surface of the first phalanx. Treatment of the OCLL was performed by surgical arthrodesis of the proximal interphalangeal joint, using two paraxial and one axial crossed lag screw, after curetting of the cyst and filling with CPB.

Regenerative Medicine for Equine Musculoskeletal Diseases

Simple Summary

Lameness due to musculoskeletal disease is the most common diagnosis in equine veterinary practice. Many of these orthopaedic disorders are chronic problems, for which no clinically satisfactory treatment exists. Thus, high hopes are pinned on regenerative medicine, which aims to replace or regenerate cells, tissues, or organs to restore or establish normal function. Some regenerative medicine therapies have already made their way into equine clinical practice mainly to treat tendon injures, tendinopathies, cartilage injuries and degenerative joint disorders with promising but diverse results. This review summarises the current knowledge of commonly used regenerative medicine treatments and critically discusses their use.

Abstract

Musculoskeletal injuries and chronic degenerative diseases commonly affect both athletic and sedentary horses and can entail the end of their athletic careers. The ensuing repair processes frequently do not yield fully functional regeneration of the injured tissues but biomechanically inferior scar or replacement tissue, causing high reinjury rates, degenerative disease progression and chronic morbidity. Regenerative medicine is an emerging, rapidly evolving branch of translational medicine that aims to replace or regenerate cells, tissues, or organs to restore or establish normal function. It includes tissue engineering but also cell-based and cell-free stimulation of endogenous self-repair mechanisms. Some regenerative medicine therapies have made their way into equine clinical practice mainly to treat tendon injures, tendinopathies, cartilage injuries and degenerative joint disorders with promising results. However, the qualitative and quantitative spatiotemporal requirements for specific bioactive factors to trigger tissue regeneration in the injury response are still unknown, and consequently, therapeutic approaches and treatment results are diverse. To exploit the full potential of this burgeoning field of medicine, further research will be required and is ongoing. This review summarises the current knowledge of commonly used regenerative medicine treatments in equine patients and critically discusses their use.

Advancement of the Subchondral Bone Plate in Translational Models of Osteochondral Repair: Implications for Tissue Engineering Approaches

Subchondral bone plate advancement is of increasing relevance for translational models of osteochondral repair in tissue engineering (TE). Especially for therapeutic TE approaches, a basic scientific knowledge of its chronological sequence, possible etiopathogenesis, and clinical implications are indispensable. This review summarizes the knowledge on this topic gained from a total of 31 translational investigations, including 1009 small and large animals. Experimental data indicate that the advancement of the subchondral bone plate frequently occurs during the spontaneous repair of osteochondral defects and following established articular cartilage repair approaches for chondral lesions such as marrow stimulation and TE-based strategies such as autologous chondrocyte implantation. Importantly, this subchondral bone reaction proceeds in a defined chronological and spatial pattern, reflecting both endochondral ossification and intramembranous bone formation. Subchondral bone plate advancement arises earlier in small animals and defects, but is more pronounced at the long term in large animals. Possible etiopathologies comprise a disturbed subchondral bone/articular cartilage crosstalk and altered biomechanical conditions or neovascularization. Of note, no significant correlation was found so far between subchondral bone plate advancement and articular cartilage repair. This evidence from translational animal models adverts to an increasing awareness of this previously underestimated pathology. Future research will shed more light on the advancement of the subchondral bone plate in TE models of cartilage repair.

Mosaic arthroplasty of the medial femoral condyle in horses - An experimental study

One Arabian and 5 Hungarian half-bred horses were used to study the macroscopic and microscopic survival of autologous osteochondral grafts in the weight-bearing surface of the medial femoral condyle (MFC). Grafts were harvested from the cranial surface of the medial femoral trochlea (MFT) under arthroscopic control. Three of them were transplanted into the weight-bearing surface of the contralateral MFC using an arthrotomy approach. Three months later this transplantation procedure was repeated on the opposite stifle joints in the same animals, but at that time transplantation was performed arthroscopically. Follow-up arthroscopy was carried out 12 months after the first operations, and biopsies were taken from both the recipient and the donor sites for histological examination. During follow-up arthroscopy, the transplanted areas looked congruent and smooth. Microscopically, the characteristics of hyaline cartilage were present in 5 out of the 10 biopsies examined; however, in the other half of biopsies glycosaminoglycan (GAG) loss and change in the architecture of the transplanted cartilage was observed. In a 16-year-old horse, all grafts broke during harvesting, and thus transplantation was not performed. No radiological signs of osteoarthritic changes were detected 9 to 12 months after the operations in the donor and recipient joints. Clinically, no lameness or effusion was present three months after the transplantations.

Clinical outcome after intra-articular administration of bone marrow derived mesenchymal stem cells in 33 horses with stifle injury

OBJECTIVE

To report outcome of horses with femorotibial lesions (meniscal, cartilage or ligamentous) treated with surgery and intra-articular administration of autologous bone marrow derived mesenchymal stem cells (BMSCs).

STUDY DESIGN

Prospective case series.

ANIMALS

Horses (n = 33).

METHODS

Inclusion criteria included horses that had lameness localized to the stifle by diagnostic anesthesia, exploratory stifle arthroscopy and subsequent intra-articular administration of autologous BMSCs. Case details and follow-up were gathered from medical records, owner, trainer or veterinarian. Outcome was defined as returned to previous level of work, returned to work, or failed to return to work.

RESULTS

Follow-up (mean, 24 months) was obtained; 43% of horses returned to previous level of work, 33% returned to work, and 24% failed to return to work. In horses with meniscal damage (n = 24) a higher percentage in the current study (75%) returned to some level of work compared to those in previous reports (60-63%) that were treated with arthroscopy alone, which resulted in a statistically significant difference between studies (P = .038). Joint flare post injection was reported in 3 horses (9.0%); however, no long-term effects were noted.

CONCLUSIONS

Intra-articular administration of BMSC postoperatively for stifle lesions appeared to be safe, with morbidity being similar to that of other biologic agents. Improvement in ability to return to work may be realized with BMSC treatment compared to surgery alone in horses with stifle injury.

Stem cell-based therapies for bone repair

This article provides an overview of the cellular and molecular events involved in bone repair and the current approaches to using stem cells as an adjunct to this process. The article emphasizes the key role of osteoprogenitor cells in the formation of bone and where the clinical applications of current research may lend themselves to large animal orthopaedics. The processes involved in osteogenic differentiation are presented and strategies for bone formation, including induction by osteogenic factors, bioscaffolds, and gene therapy, are reviewed.

Effect of age at presentation on outcome following arthroscopic debridement of subchondral cystic lesions of the medial femoral condyle: 85 horses (1993-2003)

REASONS FOR PERFORMING STUDY

Subchondral cystic lesions of the medial femoral condyle (SCMFC) are well documented in horses < or =3 years; arthroscopic debridement or enucleation of the cyst is currently the surgical treatment of choice. However, studies of occurence and outcome following surgery in older horses are lacking.

OBJECTIVE

To identify factors important in outcome for horses with SCMFC treated by arthroscopic debridement.

HYPOTHESIS

Age of horse at presentation has a significant influence on return to work following arthroscopic treatment for SCMFC. Clinical and diagnostic findings are also significant with respect to prognosis.

METHODS

A retrospective review of medical records from 6 equine referral centres identified 85 horses that underwent arthroscopic debridement of SCMFC. Clinical examination, radiographic and arthroscopic findings were analysed together with follow-up data. Univariable analysis and multivariable logistic regression models were used to determine factors affecting return to soundness. Event-time analysis was performed to evaluate return to work.

RESULTS

Older horses (>3 years) were less likely to return to soundness (P = 0.02) or to work (P = 0.04) than younger horses (< or = 3 years). Of 39 horses age 0-3 years, 25 (64%, 95% CI 49-79%) returned to soundness. Of 46 horses age >3 years, 16 (35%,95% CI 21-49%) returned to soundness. In addition, cartilage damage at sites other than the SCMFC negatively affected prognosis (P = 0.05). The hospital where treatment was performed had no influence on return to soundness.

CONCLUSIONS

Older horses carry a worse prognosis for both return to soundness and return to work.

POTENTIAL RELEVANCE

It is important for clients to be made aware of the difference in outcome between age groups.

Arthroscopic debridement of subchondral bone cysts in the distal phalanx of 11 horses (1994-2000)

REASONS FOR PERFORMING STUDY

Historically, there has been a consensus that conservative management of subchondral cystic lesions of the distal phalanx carries a poor prognosis. Surgical management has been advocated; however, there are no reports documenting its routine use and successful surgical treatment.

OBJECTIVES

To describe arthroscopically-guided curettage of distal phalangeal subchondral cystic lesions (SCLs) and report the qualitative and quantitative results in 11 affected horses age 16-33 months.

METHODS

Medical records of horses with previously treated lameness resulting from SCLs of the third phalanx were reviewed. Arthroscopic debridement of the SCLs was described. Follow-up information was obtained from race records and telephone contact with owners and trainers. The sign-rank test was used to compare performance of operated racehorses to that of unoperated siblings.

RESULTS

Ten of the 11 horses (91%) in the study returned to athletic soundness after surgical treatment and had performance records similar to their siblings.

CONCLUSIONS

Data show that arthroscopic debridement of distal phalangeal SCLs is a viable treatment for affected horses age 16-33 months and can result in a successful return to intended athletic performance. No horses younger than 16 months or older than 33 months were treated and results in horses younger or older than this group may vary in success.

POTENTIAL RELEVANCE

The description of treatment and approach used for arthroscopic curettage will increase awareness of this option and increase treatment options for this condition.

Evidence-based musculoskeletal surgery in horses

Musculoskeletal disorders comprise a large portion of the conditions treated by equine veterinarians. Surgical intervention is the treatment of choice in many cases. The body of literature describing and exploring surgical correction of musculoskeletal disorders in horses is steadily growing but still lacking. At this juncture, we can use what information we have with the understanding that as the quality of research advances, we should apply stricter standards to the evidence we use to answer our clinical questions.

Crushed bone grafts and a collagen membrane are not suitable for enhancing cartilage quality in the regeneration of osteochondral defects—An in vivo study in sheep

Hyaline joint cartilage has only a limited potential for self-repair. Some of the published techniques for osteochondral defect therapy try to improve that potential. In this study, it was hypothesised that one of those surgical techniques, the crushed transplanted bone graft together with a collagen membrane, accelerates significantly the reconstruction of the subchondral bone plate and improves the mechanical and histological quality of repaired cartilage in osteochondral defects compared to an empty control defect. In order to test this hypothesis, defects were created in the left knee of 12 sheep and filled either with autologous crushed bone graft or left empty. The animals were sacrificed after 3 (n = 6) and 6 (n = 6) months. No differences were found either macroscopically or histomorphometrically between the bone graft and empty control defects. The biomechanical as well as the histological results of the bone graft defects were inferior to the control defects with inflammatory processes caused either by bone graft or membrane remnants. Based on the results in this sheep model, the filling of subchondral bone defects with compacted cancellous bone should be carefully reconsidered.

New Surgical Treatments for Osteochondritis Dissecans and Subchondral Bone Cysts

Osteochondritis dissecans (OCD) and subchondral bone cysts (SBCs) occur commonly and at many different locations in equine limbs and can lead to secondary osteoarthritis when left untreated. Depending on the location and extent of the lesion, arthroscopic surgical debridement may be an effective treatment for returning a horse to athletic soundness. In many cases, however, additional techniques to improve the healing response in bone and cartilage are needed so as to preserve articular function. Methods for improving cartilage repair (ie, restoration of damaged cartilage)or regeneration (ie, reformation or recreation of new articular cartilage) in select cases of OCD and SBCs are discussed.

Chitosan-glycerol phosphate/blood implants improve hyaline cartilage repair in ovine microfracture defects

BACKGROUND

Microfracture is a surgical procedure that is used to treat focal articular cartilage defects. Although joint function improves following microfracture, the procedure elicits incomplete repair. As blood clot formation in the microfracture defect is an essential initiating event in microfracture therapy, we hypothesized that the repair would be improved if the microfracture defect were filled with a blood clot that was stabilized by the incorporation of a thrombogenic and adhesive polymer, specifically, chitosan. The objectives of the present study were to evaluate (1) blood clot adhesion in fresh microfracture defects and (2) the quality of the repair, at six months postoperatively, of microfracture defects that had been treated with or without chitosan-glycerol phosphate/blood clot implants, using a sheep model.

METHODS

In eighteen sheep, two 1-cm2 full-thickness chondral defects were created in the distal part of the femur and treated with microfracture; one defect was made in the medial femoral condyle, and the other defect was made in the trochlea. In four sheep, microfracture defects were created bilaterally; the microfracture defects in one knee received no further treatment, and the microfracture defects in the contralateral knee were filled with chitosan-glycerol phosphate/autologous whole blood and the implants were allowed to solidify. Fresh defects in these four sheep were collected at one hour postoperatively to compare the retention of the chitosan-glycerol phosphate/blood clot with that of the normal clot and to define the histologic characteristics of these fresh defects. In the other fourteen sheep, microfracture defects were made in only one knee and either were left untreated (control group; six sheep) or were treated with chitosan-glycerol phosphate/blood implant (treatment group; eight sheep), and the quality of repair was assessed histologically, histomorphometrically, and biochemically at six months postoperatively.

RESULTS

In the defects that were examined one hour postoperatively, chitosan-glycerol phosphate/blood clots showed increased adhesion to the walls of the defects as compared with the blood clots in the untreated microfracture defects. After histological processing, all blood clots in the control microfracture defects had been lost, whereas chitosanglycerol phosphate/blood clot adhered to and was partly retained on the surfaces of the defect. At six months, defects that had been treated with chitosan-glycerol phosphate/blood were filled with significantly more hyaline repair tissue (p < 0.05) compared with control defects. Repair tissue from medial femoral condyle defects that had been treated with chitosan-glycerol phosphate/blood contained more cells and more collagen compared with control defects and showed complete restoration of glycosaminoglycan levels.

CONCLUSIONS

Solidification of a chitosan-glycerol phosphate/blood implant in microfracture defects improved cartilage repair compared with microfracture alone by increasing the amount of tissue and improving its biochemical composition and cellular organization.

Autologous Osteochondral Grafting (Mosaic Arthroplasty) for Treatment of Subchondral Cystic Lesions in the Equine Stifle and Fetlock Joints

OBJECTIVE

To describe treatment of equine subchondral bone cysts (SBCs) by reconstruction of the articular surface with osteochondral grafts.

STUDY DESIGN

Case series of horses with SBCs unresponsive to conservative therapy.

ANIMALS

Eleven horses (1-12 years).

METHODS

SBCs were identified in 4 locations: medial femoral condyle (5 horses), lateral femoral condyle (1), distal epiphysis of the metacarpus (4), or metatarsus (1). Osteochondral autograft transplantation (mosaic arthroplasty) was performed, taking grafts from the abaxial border of the medial femoral trochlea of the unaffected limb. Graft implantation was achieved through a small arthrotomy or by arthroscopy depending on SBC location.

RESULTS

All horses improved postoperatively; 10 horses had successful outcomes with radiographic evidence of successful graft incorporation and 7 returned to a previous or higher activity level. On follow-up arthroscopy (5 horses) there was successful reconstitution of a functional gliding surface. One horse had delayed incorporation of a graft because of a technical error but became sound. One horse had recurrence after 4 years of work and soundness. One stallion was used for breeding and light riding because of medial meniscal injuries on the same limb.

CONCLUSIONS

Implantation of osteochondral grafts should be considered for SBC when conservative management has not improved lameness and there is a risk of further joint injury and degeneration.

CLINICAL RELEVANCE

Mosaic arthroplasty should be considered for treatment of subchondral bone cysts of the femoral condyle and distal articular surface of the metacarpus/tarsus in horses that are refractory to non-surgical management.

Occult Subchondral Osseous Cyst-like Lesions of the Equine Tarsocrural Joint

OBJECTIVE

To report the clinical signs, diagnosis, management, and outcome of horses with occult sub-chondral osseous cyst-like lesions of the tarsocrural joint.

DESIGN

Retrospective study.

ANIMALS

Twelve horses with subchondral osseous cyst-like lesions (SOCLs) in the tarsocrural joint.

METHODS

Information about history, examination findings, diagnostic techniques, and surgical procedures as obtained from medical records. Outcome was determined by patient re-evaluation and telephone communication with the referring veterinarian, owner, or trainer.

RESULTS

Horses were aged from 3 to 29 years. Lameness (2 weeks to 1 year) varied from moderate to severe. Synovial fluid analyses (9 horses) yielded changes consistent with suppurative inflammation and positive bacterial culture was obtained in 4 horses. Eight of 9 horses that had intra-articular analgesia had a dramatic reduction in lameness. No abnormalities were detected on tarsal radiographs in 10 horses. Scintigraphy identified foci of increased radiopharmaceutical uptake in the distal tibia or talus of all horses, and the lesion was further characterized by computed tomography in 7 horses. SOCLs were identified in the medial malleolus (5), intertrochlear groove of the talus (4), lateral malleolus (2), and distal intermediate ridge of the tibia (1). One horse was euthanatized, 6 horses had surgical debridement, and 5 horses were managed conservatively. Four horses treated surgically (67%) returned to soundness. Conservatively treated horses continued to exhibit lameness but 2 were sufficiently sound for light pleasure riding.

CONCLUSIONS

Occult lesions of the tarsus not visible on radiographs can be detected by computed tomography and scintigraphy and may be a source of lameness.

CLINICAL RELEVANCE

SOCL, possibly of septic origin, should be a differential diagnosis for persistent lameness localized to the tarsocrural joint without radiographic abnormalities. Surgical debridement of the lesions may offer the best prognosis for a return to athletic soundness.

Evaluation of a cranial arthroscopic approach to the stifle joint for the treatment of femorotibial joint disease in horses: 23 cases (1998-1999)

OBJECTIVE

To describe a single-portal cranial arthroscopic approach to the stifle joint in horses and to determine the clinical outcome in horses with femorotibial joint disease in which this approach was used.

DESIGN

Retrospective study.

ANIMALS

23 adult horses.

PROCEDURE

Medical records were reviewed to obtain information on clinical outcome in horses in which the single-portal cranial arthroscopic approach was used.

RESULTS

Twenty-nine stifle joints of 23 horses were examined arthroscopically, using the described approach. Subchondral bone cysts were treated in 19 medial femoral condyles of 12 horses. Unilateral cruciate ligament desmitis (4 horses), meniscal tearing (3), or both (2) were identified in 9 horses. Evidence of degenerative joint disease without cystic lesions or soft tissue trauma was found in 2 horses. Information on clinical outcome was obtained for 21 of 23 horses. A successful outcome was obtained in 15 of 21 horses and was defined as return to sound performance at a degree equal to or better than that prior to injury and lameness. Eight of 12 horses treated for medial femoral condylar cysts had a successful outcome. Four show horses treated for cruciate ligament lesions alone successfully returned to showing activity. None of the 3 horses with meniscal tearing were able to perform successfully.

CONCLUSIONS AND CLINICAL RELEVANCE

The femorotibial joint was evaluated through a single-portal cranial arthroscopic approach, using the femoropatellar joint as the point of access. This approach was easy to perform, allowed controlled access to the femorotibial joint, avoided accidental damage to articular structures, and required fewer access portals.