Mark Glyde

In vitro Comparison of Secure Aberdeen and Square Knots with Plasma‐ and Fat‐Coated Polydioxanone

OBJECTIVE To determine (1) the minimum number of throws to form secure Aberdeen (AB) and square knots to start (SS) and end (SE) continuous patterns, in fat- and plasma-coated polydioxanone; and (2) compare relative knot security (RKS) and knot volumes of these secure SS, SE, and AB knots. STUDY DESIGN In vitro experimental materials testing. SAMPLE POPULATION Polydioxanone suture material (3 metric). METHODS Each knot was tested 20 times, and throws incrementally added until secure SS, SE, and AB knots were found. RKS and knot volumes were calculated for SS, SE, and AB knots. RESULTS Secure SE knots needed 5 throws in plasma or fat. Secure SS knots needed 4 throws in plasma, but 5 in fat. The minimum AB configuration that was secure in plasma or fat was 3+1, however, the 4+1 AB knot was also secure in fat. Mean (SD) RKS of secure knots were: SE 59.69% (5.91), SS 67.92% (12.50), AB 81.08% (8.99). AB knots had significantly higher mean RKS than any SS or SE knot in plasma or fat (P<.001). Mean knot volume of 3+1 AB knot was significantly smaller than any secure SS or SE knots by 22.6-69.4% (P<.0001). Mean knot volume of 4+1 AB knots was significantly smaller than all fat secure SS and SE knots by 19.9-57.5% (P=.0001). CONCLUSION The knot security of the SS knot was decreased by fat coating polydioxanone suture, requiring an additional throw to keep it secure. Secure AB knots had a higher breaking strength and smaller knot volume than secure SS and SE knots. CLINICAL RELEVANCE The AB may be preferable to square knots in continuous closures. As many body fluids contain lipid, surgeons should tie knot configurations considered secure in fat. We advise tying a 4+1 AB and placing a minimum of 5 throws to tie SS and SE knots using 3 metric polydioxanone.

Triple tibial osteotomy for treatment of the canine cranial cruciate ligament-deficient stifle joint

OBJECTIVE To report the surgical findings and early post-operative complications of triple tibial osteotomy (TTO) for the treatment of cranial cruciate ligament disruption in dogs. METHODS Clinical records of 84 dogs (97 stifles) that had TTO procedures were reviewed. Surgical findings and postoperative complications were assessed. A complication was defined as any undesirable outcome resulting from TTO that required further diagnostic investigation or surgical treatment. RESULTS Mean tibial wedge angle was 13.6 degrees (range 10-20). Incomplete tibial crest osteotomy was achieved in 79% of TTO procedures. Implants were placed in the tibial crest in 67% of stifles. Early postoperative complications occurred in 23% of joints, and included avulsion of the tibial crest (9.1%), fracture at the distal cortical attachment of the tibial crest (6.2%), fibula fracture (4.1%), patellar tendonitis (3.1%), late meniscal injury (3.1%), implant complications (3.1%) and patellar fracture (2.1%). Increased patient age (p = 0.023), increased wedge angle (p = 0.009) and intra-operative fracturing of the cranial tibial cortex (p = 0.017) were significantly associated with postoperative tibial crest avulsion. Implants did not prevent tibial crest avulsion. Increased patient age (p = 0.012) was significantly associated with tibial crest fracture. CLINICAL RELEVANCE Tibial crest avulsion and fracture are the most common postoperative complications for TTO. Late meniscal injury is uncommon after TTO.

Anatomical investigation of the canine cranial tibial artery

OBJECTIVE To investigate arterial vascularity at the level of the proximal tibia as a potential source of the severe intra-operative haemorrhage, which has been previously reported as a complication during tibial plateau levelling osteotomy (TPLO) and triple tibial osteotomy (TTO) surgeries in dogs. To devise a surgical approach for the management of this complication. METHOD Eight pelvic limbs from five canine cadavers were dissected and the vascular structures at the level of the proximal tibia were identified and photographed. An arterial phase angiogram was performed on a sixth cadaver to further describe the vasculature in situ . Additional dissection was performed on four pelvic limbs to devise a medial surgical approach to the popliteal artery and the cranial tibial artery proximal to the stifle. RESULTS The cranial tibial artery was identified as the most likely source of profuse haemorrhaging if damaged during proximal tibial osteotomy. Its course and branching are described. A simple medial approach to the popliteal artery at the level of its bifurcation into the cranial and caudal tibial arteries was developed. CLINICAL RELEVANCE Understanding of the vascular anatomy at the level of the proximal tibia may prevent iatrogenic damage and resulting haemorrhage during TPLO and TTO surgeries. Temporary occlusion of the cranial tibial artery can be achieved through a simple medial approach, proximal to the stifle, in the event of severe haemorrhage associated with TPLO or TTO.

The effect of intramedullary pin size and monocortical screw configuration on locking compression plate-rod constructs in an in vitro fracture gap model

OBJECTIVE To investigate the effect of intramedullary pin size in combination with various monocortical screw configurations on locking compression plate-rod constructs. METHODS A synthetic bone model with a 40 mm fracture gap was used. Locking compression plates with monocortical locking screws were tested with no pin (LCP-Mono) and intramedullary pins of 20% (LCPR-20), 30% (LCPR-30) and 40% (LCPR-40) of intramedullary diameter. Locking compression plates with bicortical screws (LCP-Bi) were also tested. Screw configurations with two or three screws per fragment modelled long (8-hole), intermediate (6-hole), and short (4-hole) plate working lengths. Responses to axial compression, biplanar four-point bending and axial load-to-failure were recorded. RESULTS LCP-Bi were not significantly different from LCP-Mono control for any of the outcome variables. In bending, LCPR-20 were not significantly different from LCP-Bi and LCP-Mono. The LCPR-30 were stiffer than LCPR-20 and the controls. The LCPR-40 constructs were stiffer than all other constructs. The addition of an intramedullary pin of any size provided a significant increase in axial stiffness and load to failure. This effect was incremental with increasing intramedullary pin diameter. As plate working length decreased there was a significant increase in stiffness across all constructs. CLINICAL SIGNIFICANCE A pin of any size increases resistance to axial loads whereas a pin of at least 30% intramedullary diameter is required to increase bending stiffness. Short plate working lengths provide maximum stiffness. However, the overwhelming effect of intramedullary pin size obviates the effect of changing working length on construct stiffness.

A secure Aberdeen knot: in vitro assessment of knot security in plasma and fat

OBJECTIVES To determine the minimum number of throws/turns to form a secure Aberdeen knot and the maximum ear slippage for these knots using three metric polydioxanone coated in fat or plasma. To compare plasma and novel canine liquefied fat as suture coating mediums for in vitro knot security testing. METHODS Throws/turns were incrementally added until a secure knot was found for plasma and fat. Knots were tensioned until failure and remaining ear length measured. A secure knot was defined as ear slippage 3 mm or less in 20 consecutively tested knots. Ear slippages were statistically analysed. RESULTS Minimum secure configuration was a 3+1 knot in plasma and fat, and its ear slipped a maximum of 2 mm in plasma and 2.5 mm in fat. A secure 4+1 knot had a maximum ear slippage of 0.5 mm, which was significantly less than that of the 3+1 knot (P<0.0001). Fat coating suture significantly decreases in vitro knot security compared with plasma (P=0.0035). CLINICAL SIGNIFICANCE The novel fat coating medium should be considered when testing in vitro knot security as it simulates a clinical knot tying environment. A 4+1 Aberdeen knot with a 3 mm ear is recommended to tie a secure Aberdeen knot in any body fluid environment.

Stifle joint luxation in the dog and cat: The use of temporary intraoperative transarticular pinning to facilitate joint reconstruction

Multiple ligament injuries of the canine and feline stifle joint which result in luxation are uncommon. Two cats and one dog, that had sustained such a joint injury were surgically treated. A rupture of the cranial and caudal cruciate ligaments, and at least one collateral ligament was observed in all of the three animals. Prosthetic reconstruction was used, as previously described, in combination with a novel technique of intraoperative placement of a temporary trans-articular pin (TTP) to maintain intra-operative anatomical reduction. TTP placement facilitated maintenance of joint alignment during surgical reconstruction and aided appropriate tensioning of the prosthetic sutures, preventing collapse of femorotibial joint compartments. The TTP was removed prior to closure of the joint allowing immediate post-operative joint mobilisation. Based on assessment by their owners, all the animals made a complete recovery. TTP was considered a relatively simple and effective adjunctive aid for surgical treatment of traumatic luxation of the stifle joint.

Magnetic resonance imaging in the diagnosis and surgical management of sacral osteochondrosis in a mastiff dog.

The clinical, radiographic, magnetic resonance imaging (MRI), surgical and pathological findings related to an osteochondral lesion of the sacrum in a mastiff dog are described. The dog showed chronic signs of pain in its pelvic limbs. Radiography revealed a triangular mineralised opacity at the craniodorsal aspect of the sacrum consistent with sacral osteochondrosis. A T2-weighted spin-echo MRI revealed dorsal and lateral compression of the cauda equina. The osteochondral fragment was removed via a dorsal laminectomy, and the clinical signs resolved. Histological abnormalities in the fragment were consistent with a diagnosis of osteochondrosis.

The effect of intramedullary pin size and plate working length on plate strain in locking compression plate-rod constructs under axial load

OBJECTIVE To investigate the effect of intramedullary pin size and plate working length on plate strain in locking compression plate-rod constructs. METHODS A synthetic bone model with a 40 mm fracture gap was used. Locking compression plates with monocortical locking screws were tested with no pin (LCP-Mono) and intramedullary pins of 20% (LCPR-20), 30% (LCPR-30) and 40% (LCPR-40) of intramedullary diameter. Two screws per fragment modelled a long (8-hole) and short (4-hole) plate working length. Strain responses to axial compression were recorded at six regions of the plate via three-dimensional digital image correlation. RESULTS The addition of a pin of any size provided a significant decrease in plate strain. For the long working length, LCPR-30 and LCPR-40 had significantly lower strain than the LCPR-20, and plate strain was significantly higher adjacent to the screw closest to the fracture site. For the short working length, there was no significant difference in strain across any LCPR constructs or at any region of the plate. Plate strain was significantly lower for the short working length compared to the long working length for the LCP-Mono and LCPR-20 constructs, but not for the LCPR-30 and LCPR-40 constructs. CLINICAL SIGNIFICANCE The increase in plate strain encountered with a long working length can be overcome by the use of a pin of 30-40% intramedullary diameter. Where placement of a large diameter pin is not possible, screws should be placed as close to the fracture gap as possible to minimize plate strain and distribute it more evenly over the plate.

Biomechanical Comparison of a Locking Compression Plate Combined With an Intramedullary Pin or a Polyetheretherketone Rod in a Cadaveric Canine Tibia Gap Model

OBJECTIVE To compare the biomechanical properties of a 10-hole 3.5 mm locking compression plate (LCP) with 2 proximal and 2 distal bicortical locked screws reinforced with either a Steinmann pin of 30-40% the medullary diameter or a poly-ether-ether-ketone (PEEK) rod of ∼75% the medullary diameter in a cadaveric tibia gap model. STUDY DESIGN Ex vivo study. SAMPLE POPULATION Cadaveric canine tibias (n = 8 pair). METHODS Each construct had a 10-hole 3.5 mm LCP with 2 screws per fracture fragment using a comminuted tibia gap model. The Steinmann pin constructs had a 2.4 mm intramedullary pin whereas the PEEK-rod constructs had a 6 mm intramedullary PEEK rod placed. Biomechanical testing included non-destructive bi-planar 4 point bending, torsion testing, and destructive axial compression. Testing produced the responses of failure load (N) in axial compression, stiffness (N/mm or N/°) in axial compression, torsion, lateral-medial, and caudal-cranial 4 point bending. Screw position within the PEEK-rods was determined after explantation. RESULTS The PEEK-rod constructs were significantly stiffer in axial compression (P < .005), lateral-medial 4 point bending (P < .001), and in torsional loading (P < .031) than the Steinman pin constructs. There was no significant difference between the constructs for stiffness in caudal-cranial 4 point bending (P = .32). The PEEK-rod constructs failed at a significantly higher load than the Steinmann pin constructs (P < .001). All constructs failed by yielding through plastic deformation. Each screw penetrated the PEEK rod in all constructs but the position of the screw varied. CONCLUSION PEEK-rod constructs failed at significantly higher loads and were significantly stiffer in 4 point lateral-medial bending, axial compression, and torsion when compared with Steinmann pin constructs.Objective To compare the biomechanical properties of a 10-hole 3.5 mm locking compression plate (LCP) with 2 proximal and 2 distal bicortical locked screws reinforced with either a Steinmann pin of 30–40% the medullary diameter or a poly-ether-ether-ketone (PEEK) rod of ∼75% the medullary diameter in a cadaveric tibia gap model. Study Design Ex vivo study. Sample Population Cadaveric canine tibias (n = 8 pair). Methods Each construct had a 10-hole 3.5 mm LCP with 2 screws per fracture fragment using a comminuted tibia gap model. The Steinmann pin constructs had a 2.4 mm intramedullary pin whereas the PEEK-rod constructs had a 6 mm intramedullary PEEK rod placed. Biomechanical testing included non-destructive bi-planar 4 point bending, torsion testing, and destructive axial compression. Testing produced the responses of failure load (N) in axial compression, stiffness (N/mm or N/°) in axial compression, torsion, lateral-medial, and caudal-cranial 4 point bending. Screw position within the PEEK-rods was determined after explantation. Results The PEEK-rod constructs were significantly stiffer in axial compression (P < .005), lateral-medial 4 point bending (P < .001), and in torsional loading (P < .031) than the Steinman pin constructs. There was no significant difference between the constructs for stiffness in caudal-cranial 4 point bending (P = .32). The PEEK-rod constructs failed at a significantly higher load than the Steinmann pin constructs (P < .001). All constructs failed by yielding through plastic deformation. Each screw penetrated the PEEK rod in all constructs but the position of the screw varied. Conclusion PEEK-rod constructs failed at significantly higher loads and were significantly stiffer in 4 point lateral-medial bending, axial compression, and torsion when compared with Steinmann pin constructs.

Dual Bone Fixation: A Biomechanical Comparison of 3 Implant Constructs in a Mid-Diaphyseal Fracture Model of the Feline Radius and Ulna.

OBJECTIVE To compare the biomechanical properties of dual bone fixation (DBF) constructs to radial locking compression plating (LCP) in an ex vivo feline antebrachial fracture gap model. STUDY DESIGN Ex vivo study. SAMPLE POPULATION Cadaveric feline antebrachii (n=12 pairs). METHODS Antebrachii were radiographed to confirm normal skeletal appearance and maturity. After creation of a 5 mm radial and ulnar ostectomy, each antebrachium received 1 of 3 constructs using an incomplete randomized block design (n=8 per group). All groups received a 10 hole 2.0 mm radial LCP. DBF groups received either a 1.2 mm ulnar intramedullary pin (LCP with pin) or an 8 hole 2.0 mm ulnar LCP in addition to the radial LCP. Biomechanical testing was performed in axial compression and caudocranial and mediolateral 4-point bending before destruction in axial compression. RESULTS DBF constructs (LCP with pin and dual LCP) were significantly stiffer than radial LCP alone in axial compression and caudocranial bending. There were no differences between LCP with pin and dual LCP constructs in axial compression and caudocranial bending or between any constructs in mediolateral bending. Failure load was significantly greater for dual LCP than LCP with pin or LCP alone constructs. Failure loads were not different between LCP with pin and LCP alone. CONCLUSION DBF significantly increased construct stiffness and strength. Given the high complication rate reported in cat antebrachial fractures when only the radius is stabilized, surgeons should consider DBF.