Introduction

• Arthroscopy is the most useful tool for both diagnosis and treatment of joint, tendon sheath and bursal lesions in the horse.
• It is a specialist procedure which requires considerable equipment and surgical skills.
• Has completely superseded arthrotomy and other open surgical procedures in joints.

Uses

Diagnostic applications

• Assessment of soft tissue structures of joints: ligaments, synovium, menisci, plicae and joint capsule.
• Assessment of joint surface and bone: osteoarthritis, fractures, cartilage and subchondral lesions.
• Tenosynovioscopy Tenosynovioscopy for examination of the internal structures of tendon sheaths including tendons, ligaments, synovial lining, sheath wall, vincula and mesotendon.
• Evaluation of lesions within bursae including synovium, capsule, tendons, ligaments, cartilage surfaces and bone Bursoscopy: overview.

Therapeutic applications

• Arthroscopically guided fracture repair of fractures within the joint or entering it.
• Removal of osteochondral or osteochondrosis fragment(s).
• Debridement of articular cartilage defects.
• Joint lavage.
• Treatment of synovial sepsis.
• Debridement of intrasynovial soft tissue lesions such as meniscal or cruciate ligament tears, S/DDFT lesions, and retinacula tears in the intercalcaneal bursa.

Carpus

• To examine the midcarpal (intercarpal) Intercarpal: arthroscopy, antebrachiocarpal (radiocarpal) Radiocarpal: arthroscopy joints, dorsal and palmar pouches.
• Surgical removal of osteochondral fragments/chip fractures Carpus: fracture - chip.
• Debridement of subchondral bone defects.
• Examination of the intercarpal ligaments and debridement of any tears.
• Treatment of osteochondritis dissecans Bone: osteochondrosis and subchondral cystic lesions Bone: subchondral cysts.
• Lag screw fixation of carpal slab fractures Carpus: fracture - slab Bone: slab fracture repair - lag screw and other carpal chip fractures.
• Treatment of septic arthritis Joint: septic arthritis - adult and osteitis Bone: osteitis - septic.

Elbow

• Diagnostic evaluation of the joint in cases of lameness localized to the elbow joint Elbow: arthroscopy.
• Surgical treatment of sepsis of the elbow joint, osseous cyst-like lesions, osteochondrosis, intra-articular fractures and osteoarthritis Elbow: osteoarthritis.

Fetlock

• Diagnostic procedures in the dorsal metacarpophalangeal joint, palmar or plantar fetlock joint Fetlock: arthroscopy.
• Removal of osteochondral fragments of the dorsal aspect of the proximal phalanx.
• Debridement of articular cartilage damage on the dorsal margin of the proximal phalanx
• Treatment of developmental fetlock disorders including osteochondritis dissecans Bone: osteochondrosis and subchondral bone cysts MCP / MTP joint: developmental orthopedic diseases.
• Treatment of traumatic damage to the joint and joint capsule.
• Removal of the enlarged synovial plicae in chronic proliferative synovitis MCP / MTP joint: chronic proliferative synovitis.
• Removal of apical, abaxial and basilar fragments of the proximal sesamoid bones Proximal sesamoid: fracture - arthroscopic removal.
• Removal of osteochondral fragments associated with the palmar or plantar aspect of the proximal phalanx.
• Repair of condylar metacarpal fractures MC / MT 3: fracture, fractures of the proximal phalanx Proximal phalanx: fracture and proximal sesamoid bones Proximal sesamoid: fracture.
• Treatment of septic arthritis Joint: septic arthritis - adult and osteitis Bone: osteitis - septic.
• Debridement of axial osteitis of the proximal sesamoid bones and lesions of the intersesamoidean ligament Intersesamoidean ligament: disease.
• Debridement of avulsions of the suspensory ligament insertions.

Stifle

• Diagnostic procedures in the femoropatellar and femorotibial joints Stifle: arthroscopy.
• Treatment of patellar fractures Patella: fracture and fragmentation of the distal patella Patella: fragmentation.
• Treatment of femoropatellar osteochondrosis Stifle: femoropatellar osteochondrosis and femorotibial subchondral bone cysts Stifle: femorotibial subchondral bone cyst.
• Diagnosis and treatment of cartilage lesions on the medial condyle of the femur.
• Debridement of meniscal tears Stifle: trauma - meniscal injuries to the cruciate ligaments and meniscal cysts.
• Treatment of fractures of the medial tibial intercondylar eminence.
• Treatment of septic arthritis Joint: septic arthritis - adult and osteitis Bone: osteitis - septic.
• Standing diagnostic arthroscopy of the stifle joints has also been published.

Tarsus

• Diagnostic procedures in tarsocrural joint Tarsus: arthroscopy.
• Treatment of osteochondrosis in the hock Tarsus: osteochondrosis.
• Treatment of cystic lesions of the proximal trochlea of the talus Bone: subchondral cysts.
• Treatment of septic arthritis Joint: septic arthritis - adult and osteitis Bone: osteitis - septic.
• Removal of lateral malleolar fractures.
• Treatment of intra-articular fractures in the hock Tarsus: fracture.
• Tears and avulsions of the joint capsule and collateral ligaments Tarsus: trauma - collateral ligament.

Shoulder

• Diagnosis and treatment of scapulohumeral osteochondrosis Shoulder: arthroscopy.
• Diagnosis and treatment of lameness localized to the scapulohumeral joint including osteoarthritis Shoulder joint: disease - overview and articular fractures Scapula: fracture.
• Treatment of septic arthritis Joint: septic arthritis - adult and osteitis Bone: osteitis - septic.

Distal and proximal interphalangeal joints

• Diagnostic and surgical arthroscopy is performed on the dorsal and palmar/plantar compartments of both joints.
• In the distal joint indications for surgery include:
  • Osteochondral fragments of the extensor process of the distal phalanx, including removal and lag screw fixation.
  • Removal of abaxial articular fragments; treatment of cysts of the subchondral bone Bone: subchondral cysts of the distal phalanx or distal middle phalanx.
  • Arthroscopic visualization during repair of sagittal fractures of the distal phalanx Distal phalanx: fractures.
  • Repair of fractures of the middle phalanx Middle phalanx: fracture.
  • Sepsis of the joint Joint: septic arthritis - adult.
• In the proximal joint indications for surgery include:
  • Removal of osteochondral fragments from the dorsal compartment.
  • Removal of fragments of the palmar/plantar margin of P2.

Coxofemoral joint

• Diagnostic arthroscopy of the coxofemoral joint has been used to evaluate lameness localized to the joint, tearing of the ligament of the head of the femur, osteoarthritis, fracture of the acetabulum and osteochondrosis Coxofemoral joint: disease - overview.
• Surgical treatment has been described for femoral head cartilage lesions, tearing of the ligament of the head, osteochondrosis, acetabular chip fractures and infectious arthritis.

Tenoscopy

• Digital flexor tendon sheath for diagnostic and surgical cases including:
  • Longitudinal tears of the SDFT SDFT: tendinitis/DDFT DDFT: tendinitis.
  • Tears of the manica flexoria.
  • Complex tenosynovitis Digital sheath: tenosynovitis.
  • Palmar/plantar annular ligament desmitis Palmar / plantar annular ligament syndrome and desmotomy Annular ligament: transection - palmar / plantar.
  • Treatment of wounds and sepsis of the sheath.
• Carpal sheath for diagnostic and surgical cases, including:
  • Removal of radial osteochondroma Carpus: osteochondroma and radial physeal exostoses; fractures of the accessory carpal bone affecting the sheath Accessory carpal: fracture.
  • Tears of the radial head of the DDFT.
  • Tears of the S/DDFT within the sheath.
  • Desmotomy of the accessory ligament of the SDFT and DDFT Accessory ligament SDFT: desmotomy Accessory ligament DDFT: desmotomy.
  • Carpal release procedure Palmar carpal retinaculum: section for carpal tunnel syndrome Carpus: sheath tenosynovitis.
• Tarsal sheath for diagnostic and surgical cases, including:
  • Tearing of the lateral digital flexor tendon.
  • Removal of tenosynovial masses and resection of adhesions.
  • Debridement of the sustentaculum tali Tenosynovioscopy following traumatic injury.
  • Identification and treatment of synovioceles.
  • Traumatic injury and sepsis of the sheath Tarsus: tarsal sheath tenosynovitis.
• Carpal and tarsal extensor sheath for diagnostic and surgical cases, including:
  • Persistent tenosynovitis Carpus: sheath tenosynovitis Tarsus: tarsal sheath tenosynovitis after trauma.
  • Tearing of associated contained tendon; wounds and infection.

Bursoscopy

• Calcaneal bursae are examined diagnostically and surgically for Calcaneal bursa: bursoscopy:
  • Tearing of the calcaneal insertions of the SDFT and unstable subluxation of the SDFT.
  • Osteolytic lesions and traumatic fragmentation of the calcaneus.
  • Sepsis of the bursae after penetration.
• Intertubercular (bicipital) bursa is examined diagnostically and surgically for Humerus: bicipital bursa - bursoscopy:
  • Investigation of lameness localized to this site Humerus: bicipital bursa - disease.
  • Treatment of intrathecal fragmentation of the supraglenoid tubercle of the scapula and lateral tubercle of the humerus.
  • Injuries of the bicipital tendon.
  • Contaminated and infected bursa.
• Podotrochlear (navicular) bursa is examined diagnostically and surgically for Navicular bursa: bursoscopy:
  • Lesions of the DDFT.
  • Lesions of the palmar fibrocartilage and subchondral bone within the bursa.
  • Penetrating injuries of the navicular bursa.

Advantages

• Synovial structures can be examined in detail through small stab incisions.
• New conditions and lesions have been documented that were not known or documented by imaging modalities.
• Less surgical trauma to the joint and patient, and less post operative pain.
• Considerable cosmetic and functional advantages over previous open surgeries.
• Much less post operative care required and less complications mean owners and trainers are more likely to consider surgery in individual patients.
• Decreased convalescence time, earlier return to work and improved results in some cases has proved very beneficial in the management of equine joint and synovial structure problems.
• Decreased requirement for palliative therapy.

Disadvantages

• Site of pain or lameness must be localized to specific joint or synovial structure before surgery is undertaken.
• High degree of surgical training is required.
• Considerable investment in equipment and facilities is required.
• Usually performed under general anesthesia Anesthesia: general - overview although limited diagnostic arthroscopy is undertaken in some joints such as the stifle and fetlock.

Obstructed field of view

• Hemarthrosis:
  • Often not a major problem, particularly with modern fluid supply systems. In the distal limb, dorsal recumbency and the use of an Esmarch bandage and tourniquet are often helpful, particularly where hemorrhage is anticipated.
  • Pre-existing pathology particularly severe synovial inflammation and hyperemia.
  • From debrided bone and particularly soft tissues.
  • Usually not a problem while the joint is distended but may become one when the joint is re-entered, after allowing the joint to collapse. Flush the cavity, and then close the outflow cannula and redistend.
  • Bleeding from subchondral bone is a useful indicator for the depth of debridement, so may need to release fluid pressure during procedure to assess surgery and hemorrhage.
• Synovial villi:
  • May be a localized or more general problem in individual cases.
  • The latter is usually due to inadequate fluid distension or loss due to an open outflow portal or instrument portal, particularly following removal of a large joint fragment.
  • Capsular fibrosis of the joint may limit distension as will subcutaneous extravasation of fluid.
  • To limit these problems the joint or other synovial structure should be thoroughly examined at the start of surgery and with a closed outflow portal.
  • Small fragments should be removed before creating larger portals for removal of large fragments.
  • Reinsert instrument to block a large portal.

• Villi can be displaced with a probe or removed surgically with hand tools or more effectively with careful limited use of motorized instruments.

• Extravasation of fluid:
  • More common problem in the antebrachiocarpal (radiocarpal) joint.
  • Once present, limits the extent of joint distension → reduced visualization → may need to delay procedure several days.
  • Associated with the instrument portal shape and positioning/patency, excessive perfusion pressure, and excessive manipulation of instruments → opening up a subcutaneous plane for fluids to leak into.
  • Also due to combination of open inflow cannula and blocked outflow portal at the skin or subcutaneous level, ie when instrument is inserted or subcutaneous insertion of trocar or scope.
  • Problem is reduced by:
    • Reducing inflow pressure while fragments are removed.
    • Turn-off fluid while portals are created.
    • Create skin incision before the blade is advanced into the structure.
  • Most encountered as a problem in the scapulohumeral and stifle joints, plus the tarsal and carpal tendon sheaths.
  • Areas of excessive subcutaneous extravasation of fluid can be manually massaged at the end of surgery before skin closure to decrease the swelling.
  • No long-term consequences have been observed and the swelling usually dissipates within 24-48 hours.

Other intra-operative complications

• Articular cartilage damage, particularly partial thickness:
  • Iatrogenic injury during surgery with arthroscope, trocar or instruments.
  • Use careful technique.
  • Ensure joint distension is adequate before entering joint.
• Iatrogenic damage to perisynovial structures during arthroscope or instrument insertion.
  • Surgery of the digital flexor tendon sheath may damage the palmar/plantar neurovascular bundle, particularly in thick skinned cobs and drafts, and the carpal sheaths of the extensor carpi radialis and common digital extensor tendons are at risk. Careful palpation, portal creation and inspection are important to limit problems.
• Intra-articular broken instruments:
  • Usually due to the use of inappropriate force by surgeon.
  • Use appropriately sized instruments and not disposable instruments.
  • Cracked arthroscope lens - of no consequence to patient but expensive.
  • May be due to contact with instrument or flexion of leg while scope is still in the joint.
  • Other instruments may break in the joint - retrieve any fragments with forceps or magnetic retrievers as soon as possible. Intra-operative radiography may help identify the position of fragments.
• Intra-articular foreign bodies:
  • Small metal fragments from instruments.
  • Contamination with hair and other debris following needle or instrument insertion.
  • Flushing should remove them.
  • No long-term impact.

Requirements

Preparation

Procedure

Aftercare

Outcomes

Prognosis

• Determined by specific pathology of each case.

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Marshall K M & Adkins A R (2014) Synovial herniation as a complication of arthroscopy in a Thoroughbred yearling. Equine Vet Educ 26 (6), 288-291 VetMedResource.
• Fowlie J G et al (2011) Comparison of conventional and alternative arthroscopic approaches to the palmar/plantar pouch of the equine distal interphalangeal joint. Equine Vet J 43 (3), 265-269 PubMed.
• Muurlink T, Walmsley J, Young D & Whitton C (2009) A cranial intercondylar arthroscopic approach to the caudal medial femorotibial joint of the horse. Equine Vet J 41 (1), 5-10 PubMed.
• Minshall G J & Wright I M (2006) Arthroscopic diagnosis and treatment of intra-articular insertional injuries of the suspensory ligament branches in 18 horses. Equine Vet J 38 (1), 10-14 PubMed.

Other sources of information

• McIlwraith C W, Nixon A J & Wright I M (2015) Diagnostic and Surgical Arthroscopy in the Horse. 4th edn. Mosby Elsevier, USA.
• Richardson D (2004) Arthroscopic Surgery in Standing Horses. In: Proc 43rd BEVA Congress. Equine Vet J Ltd, UK. pp 157.