Hufgelenkarthrodese mittels drei 5,5 mm-Zugschrauben von dorsoproximal nach palmarodistal bei einem adulten Pferd – eine alternative Technik
Arthrodesis of the distal interphalangeal joint in a horse using three 5.5 mm cortical screws in a dorsoproximal to palmarodistal direction in an adult horse – an alternative technique
Adolphsen N, Zanker A
DOI: 10.21836/PEM20210507
Jahr: 2021
Volume: 37
Ausgabe: 5
Seiten: 510–517
In der Pferdemedizin werden Arthrodesen des Hufgelenkes („High-Motion-Joint“), im Gegensatz zu Arthrodesen anderer Gelenke wie Krongelenke oder Tarsometatarsalgelenke („Low-Motion-Joints“), eher selten durchgeführt. Der folgende Bericht schildert eine bisher nicht veröffentlichte OP-Technik sowie den sehr guten postoperativen Verlauf des Falles.A 9 year old PRE stallion was presented with severe arthrosis of the right front coffin joint causing a severe lameness (grade IV-V/V, AAEP-lameness scale). This severe arthrosis was caused by a septic arthritis after an injection into the coffin joint using unknown substances one year prior to presentation. After the mentioned injection, the horse became increasingly lame and was running a high fever up to 40,5 °C (104,9°F). Treatment at that time was only palliative, without using antimicrobials. At our first visit, one year after the described injection, the horse was in severe pain showing a lameness grade IV-V/V (AAEP lameness scale) with a firm swelling proximal to the coronary band. On the lateromedial radiograph, the coffin joint was profoundly arthritic with a high degree of osteophytes propagating dorsally. The second phalanx (P2) showed serious osteophytes involving the entire dorsal surface of the bone and moderate osteophytes on the palmar surface. The navicular bone had a spike like osteophyte propagating proximally. Soft tissue swelling on the dorsal joint surface could be noticed. On the dorsopalmar view, the appearance of P2 seemed heterogenous due to the overlap of the dorsal and palmar osteophytes and the coffin joint was collapsed laterally. A high degree of osteophyte formation was also noted around the joint. The coffin joint was anesthetized using the dorsal approach with 6 mls of Mepivacaine (Mepivacaine hydrochloride 20 mg/ ml, Puren Pharma), which showed a significant reduction in the lameness grade (about 70 % after five minutes, after ten minutes further amelioration). The synovial fluid appeared watery and the cell count was 0,6 × 109/L, which does not indicate a septic joint. An attempt was made to treat the joint medically using hyaluronic acid (3 ml HY 50 Vet. 17 mg/ml) and two corticosteroids (triamcinolone acetonide (1 ml Triamhexal® 10 mg/ml) and dexamethasone (1 ml Lipotalon® 2,5 mg/ml)). After two weeks the horses’ lameness improved to grade III/V (AAEP lameness scale) for one week. After that the horse deteriorated to its former grade of lameness within eight days. Due to a lack of other options, the decision was made to perform a coffin joint arthrodesis. The surgery was performed in lateral recumbency with the affected joint uppermost. To achieve maximal stability, the decision was made to use the 5.5 mm cortical screw system. The drilling direction was established by using hypodermic needles under radiographic guidance. The first incision was made centrodorsal on P2, splitting the extensor tendon along its length for two centimeters. The glide hole in P2 was made from dorsoproximal to palmarodistal. The planned end of the glide hole (at the joint space) was identified radiographically. After that, the thread hole was drilled using radiographic guidance. Finally, the hole was countersunk, the length was measured and tapped creating the threads. Special care was taken to use a length of screw that was able to compress the joint space. The other two screws were inserted in the same fashion lateral and medial to the first one. All the screws were tightened immediately after insertion. The horse was in external coaptation using a half limb cast for 14 days, and then a splint bandage was used for another four weeks. Six weeks after surgery, no substantial bony changes could be found at the operated region. Despite complications like non weightbearing lameness on the non-operated limb for 24 hours, which was due to nerve trauma (we did not consider this complication to be induced by the damage of muscle tissue since there was no swelling, heat or pain in the region of interest), and a non-reduction in the lameness grade on the operated limb for another eight to ten weeks, the described arthrodesis technique led to a substantial success. One-year post operatively, the horse was sound in trot on a straight line but showed a slight lameness on the circle (grade I-II/IV, AAEP lameness scale) and could be used for pleasure riding. One year after surgery, the joint space appeared fused to a high degree and the navicular bone seemed incorporated into P2 and P3 on the lateromedial. The dorsopalmar view established a fusion of about 50 % within the coffin joint and a more homogenous texture at the level of P2. An osteophyte was bridging the joint laterally.