| Abstract: | Objectives: Our objectives were to describe an endoscopic technique of the navicular bursa, describe the endoscopic anatomy, assess its feasibility on live horses undergoing an exploratory endoscopy, and assess the usefulness of standard arthroscopic instruments introduced via a contralateral portal.Study design: This was an anatomic study on cadaver limbs and endoscopic observation on clinical cases associated with problems of the navicular bursa and/or navicular bone.Animals or sample population: The sample population was 4 cadaver forelimbs of 2 horses weighing 300 to 450 kg and 8 live horses and one pony weighing 180 to 550 kg with navicular bursa disease.Methods: One cadaver limb was left untouched; the 3 others were dissected in a different way. Dissection and endoscopy of the navicular bursa were performed on the cadaver limbs with 4-mm and 2.7-mm 30° forward oblique arthroscopes. Relative positions of the arthroscope and of various arthroscopic instruments in the bursa were observed. Then, exploratory endoscopy of the navicular bursa was performed on live horses suspected of navicular bursa disease after clinical, radiographic, and/or sonographic examination. Visualization with saline solution and carbon dioxide was compared. Standard arthroscopic instruments were introduced according to the lesions observed. Some lesions were treated and a lavage of the navicular bursa was performed in all horses. Postoperative recovery was followed until 3 months after surgery.Results: Most parts of the anatomic structures of the navicular bursa could be observed with the 4-mm or 2.7-mm arthroscope, and standard arthroscopic instruments could be introduced into the bursa. A lavage of the bursa could be performed in all horses and no iatrogenic damage or postoperative complications were noted.Conclusion: Endoscopy of the navicular bursa with standard arthroscopic instruments is a feasible technique in horses and could be a useful diagnostic modality in suspected disease of this area.Clinical application: Diagnostic endoscopy in horses suspected of navicular bursa disease can be used to complement other diagnostic means. It already is used for treatment of septic bursitis; endoscopy of the navicular bursa could have other therapeutic applications in the future. IntroductionArthroscopy of the dorsal aspect of the distal interphalangeal joint in horses was used for removal of extensor process fractures and for diagnosis examination of this joint.1 Arthroscopy of the palmar (plantar) aspect of the distal interphalangeal joint was described for removal of fibrin, intra-articular lavage in septic arthritis, and to access some fractures of the distal sesamoid (navicular) bone and middle and distal phalanges.2Endoscopy of the bursa podotrochlearis (navicular bursa) was recently described for treatment of septic bursitis.3 In this procedure, the instruments were mostly introduced through the original penetrating wound at the frog and through the flexor digitorum profundus (deep digital flexor tendon). In another study,4 the authors observed the navicular bursa in cadaver limbs and compared the endoscopic observation with pathologic findings.Lesions of the navicular bursa and contiguous anatomic structures (deep digital flexor tendon, palmar/plantar fibrocartilaginous facies flexoria flexor surface] of the navicular bone, ligamentum sesamoideum distale impar impar ligament], and ligamenta sesamoidea collateralia collateral sesamoidean ligament]) can be associated with navicular syndrome.5, 6 and 7Conventional radiographs allow evaluation of osseous lesions of the navicular bone (loss of cortico-medullary definition, irregularity of the sagittal ridge of the facies flexoria, and irregularity or thickening of the flexor cortex)5, 8 and 9 but are less sensitive for soft tissue evaluation.Ultrasonography allows the evaluation of some soft tissue lesions.10 It can be performed at the palmar aspect of the pastern or by a transfurcal approach.Scintigraphy is more sensitive than radiography in the evaluation of navicular syndrome, and it can complete an inconclusive radiographic examination.11Magnetic resonance imaging (MRI) and computed tomography (CT) scan are also valuable diagnostic means for navicular syndrome in revealing some osseous abnormalities undetectable with conventional radiographs8 and 12 and, for MRI, in providing a reliable evaluation of soft tissues.13, 14 and 15The objectives of this study were to document an endoscopic approach to the navicular bursa, describe the endoscopic anatomy, assess the usefulness of standard surgical instruments introduced via a contralateral portal (which could have potential benefits in diagnosis or treatment of lesions in this area), and finally, to assess the feasibility of this technique in live horses undergoing an exploratory endoscopy. InstrumentationThe procedure was performed at 2 different clinics with different sets of instruments. Equipment used included two 4-mm (Dyonics or Storz) and one 2.7-mm (Optomed) 30° forward oblique arthroscopes connected to a light cable (Optomed or Storz) and light source (Stryker or Storz). The arthroscope was connected to a camera (Stryker or Storz) and a video system, which allowed recording and printing of endoscopic views. Various surgical instruments were used: a blunt tendon knife for splitting surgery, motorized synovial resector blades (Dyonics), straight and curved curettes (Sontek), Basket type synoviectomy forceps (Acufex), and Ferris-Smith rongeurs (Sontec). Procedure Cadaver limbsFour distal forelimbs from 2 French Warm Blood equine cadavers weighing 300 to 450 kg with no lameness history were examined. Radiographs of the navicular bone were previously performed to document the absence of preexisting lesions. Three views were used: Dorso (60°) proximal-palmarodistal oblique, lateromedial, and palmaro (45°) proximal-palmarodistal oblique.The first limb was partially dissected (skin and subcutaneous tissue were removed) and the navicular bursa was examined by introducing the 4-mm arthroscope lateral to the deep digital flexor tendon.Navicular bursa endoscopy was performed in a similar way on the second undissected limb. The procedure was recorded on videotape and endoscopic photographs were printed. Various instruments were introduced by a medial approach, symmetrically to the arthroscope portal.The third limb was partially dissected like the first and cut in a sagitttal way with a sharp circular saw. The 4-mm arthroscope was introduced into the bursa and its progression from the skin to the bursa was observed by a sagittal view (Figs 1 and 2).Fig. 1. Third dissected limb cut in a sagittal way. The 4-mm arthroscope is introduced into the digital sheath and its progression to the navicular bursa is observed. DDFT, Deep digital flexor tendon; Ds, digital sheath; Mb, separating membranes (Ds synovial layer + connective tissue + Nb synovial layer) between the digital sheath and the navicular bursa; Nav, navicular bone; Nb, navicular bursa; P2, 2nd phalanx; P3, 3rd phalanx.
Fig. 2. Same limb as in Fig 1. Sagittal view of the 4-mm arthroscope introduced lateral to the DDFT into the navicular bursa. DDFT, Deep digital flexor tendon; Ds, digital sheath; Mb, separating membranes (Ds synovial layer + connective tissue + Nb synovial layer) between the digital sheath and the navicular bursa; Nav, navicular bone; Nb, navicular bursa; P2, 2nd phalanx; P3, 3rd phalanx. The limb was flexed and anatomic modifications were observed.The fourth limb was dissected; skin, subcutaneous tissue, distal digital annular ligament, digital sheath, and the tendon of the flexor digitorum superficialis (superficial digital flexor) were removed at the palmar pastern level. The hoof, the palmar part of the cartilaga ungulara (ungular cartilage), and the bulbs of the heels also were removed. The tendon of the deep digital flexor was transversally cut at half-pastern level and reflected distally to expose the narrow synovial structures (both digital sheath and navicular bursa synovial layers and connective tissue) separating the digital sheath from the navicular bursa.First, the arthroscope was introduced laterally and various instruments were introduced medially. The portals and relative axis of the arthroscope and instruments were observed in a proximo-distal view (Fig 3).
Fig. 3. Fourth dissected limb. The tendon of the deep digital flexor tendon is transversally cut and reflected distally to expose the synovial membranes separating the digital sheath from the navicular bursa. The arthroscope is introduced laterally and various instruments are introduced medially. DDFT, Deep digital flexor tendon; Ds, digital sheath; Mb, separating membranes between the digital sheath and the navicular bursa. Then, the synovial structures separating the digital sheath from the navicular bursa were removed and the position of various instruments on the fibrocartilaginous facies flexoria of the navicular bone was observed (Fig 4).
Fig. 4. Same limb as in Fig 3. The synovial membranes separating the digital sheath from the navicular bursa is removed and the position of various instruments on the fibrocartilagineous facies flexoria of the navicular bone is observed. DDFT, Deep digital flexor tendon; Coll, collateral sesamoidean ligament; Ff, facies flexoria of the navicular bone; Imp, impar ligament. AnimalsAn exploratory endoscopy of the navicular bursa was performed on 8 live horses and a pony from 4 to 12 years of age weighing 180 to 550 kg. These horses presented clinical and radiographic or sonographic signs of navicular bursa disease associated with lesions of the navicular bone or the distal interphalangeal joint. These cases are shown in the Table. |
