Pes anserinus interposition in a proximal tibial physeal fracture. A case report

A ten-year-old girl suffered a Salter-Harris Type II fracture of the proximal tibia. Inspection revealed interposition of the pes anserinus (PA) within the open physis, which prevented reduction. This may be the first case report of PA interposition.     

Tetracycline labeling as an aid to complete excision of partial physeal arrest: a rabbit model.

We determined whether ultraviolet (UV) visualization of tetracycline-labeled bone allows more complete excision of experimentally created physeal arrests while minimizing required bone resection. Lateral distal femoral growth arrests were surgically created bilaterally in eight 6-week-old New Zealand white rabbits, given 3 daily oxytetracycline doses (10 mg/kg); the animals were killed 6 weeks postoperatively. Femurs were excised and dissected free of soft tissue. Ten of 16 operated femurs randomized into two groups had consistent deformity. In group I, arrest was excised with a high-speed burr without, and, in group II, with ultraviolet visualization. In group II, metaphyseal bone and calcified arrest glowed brightly, contrasting well with the epiphyseal plate. All excised specimens were examined under x 9 magnification to assess remaining bone bridges. Excision defects were filled with modeling clay, which was then removed and weighed. Thorough excision was confirmed in each specimen. Resection was easier and less bone usually was resected in the UV group (difference not statistically significant). This technique would best be used in resection of arrests involving small physes such as the distal radius, in which maximal visualization and minimal resection are essential to preserve all possible growth potential. Tetracycline labeling and intraoperative UV visualization of fluorescence allows thorough excision of partial physeal arrest while minimizing required bone resection.     

Effect of interposed periosteum in an animal physeal fracture model

To study the effect of interposed periosteum on physeal fracture healing, 52 skeletally immature female Harlan Sprague-Dawley rats, 4 to 5 weeks of age, were randomized to one of three cohort groups. All animals underwent surgical dissection of the left proximal medial tibia; dissection consisted of superficial exposure and incision of a standard periosteal flap. Animals in Group I (fracture alone) underwent physeal fracture; those in Group II (fracture and periosteum) underwent physeal fracture with interposition of periosteum in the fracture site, and those in Group III (positive control) underwent physeal fracture, excision of 1/2 of the growth plate, and interposition of periosteum in the defect. After histologic examination of serial sections, fracture alone resulted in physeal injury frequently associated with small bar formation without a reduction in leg length. With the addition of interposition of periosteum into the fracture site, a small, but statistically significant, increase in leg length discrepancy frequently associated with small histologic bar formation occurred when compared with fracture alone.     

The Whitaker test: experimental analysis in a canine model of partial ureteric obstruction

The Whitaker test has been described as a means of reaching a diagnosis in equivocal upper urinary tract obstruction, but there has been conflicting evidence regarding the validity of this test. The present study assesses the reliability of the test in an experimental model which creates an accurate and predetermined degree of partial obstruction of the ureter. The Whitaker test was performed using the standard perfusion rate of 10 ml./min. in male adult dogs using a long-term indwelling renal intrapelvic cannula before and after application of ureteric obstruction, and after one month. Control animals underwent a sham procedure. Results of in vivo and in vitro perfusion studies were compared. Perfusion studies at multiple flow rates were also performed. The Whitaker test reliably detected the presence of ureteric obstruction and the degree of partial obstruction could be determined. Multiple flow rate studies did not significantly improve test results. Provoked pressures in the highest grade of obstruction were less than expected and this may be due to pyelovenous reflux.     

A canine model of laparoscopic segmental liver resection

Laparoscopic hepatectomy has been recently proposed for the treatment of liver tumors, however there is a lack of experimental models to study surgical technique and the metabolic reactions after this procedure. The dog is an important animal for research but the laparoscopic hepatectomy model is not well established in this animal. We describe the surgical laparoscopic technique of left liver segmentectomy in the dog and the preliminary results of this procedure. Female dogs weighting more then 15 kg were used. Four transversal abdominal incisions (two of 1 cm and two of 0.5 cm) were made for the introduction of the video camera and the other laparoscopic instruments. The liver was inspected and the left lobe was mobilized through incision of the left triangular hepatic ligament. The vascular pedicle corresponding to the left medial lobe (corresponding to segment II) was identified, dissected, and clamped, delimiting a correspondent ischemic area. The hepatic parenchyma was divided according to the previous delimitation with minimum bleeding. The segment of the liver was then removed through an enlarged abdominal incision. The incisions were closed by continuous suture. The mean time of the procedure was forty minutes. We observed normal clinical evolution without any sign of complications due to the hepatic resection, and normal augmentation of body weight on follow-up of more than 3 months. Left hepatectomy in the dog is a viable procedure and may serve for surgical training and development of research projects in this field.     

Chondropathy after meniscal tear or partial meniscectomy in a canine model.

A primary goal in considering treatment for meniscal injuries is the preservation of the health of the articular cartilage. However, the chondroprotective effects of various techniques for meniscal injury treatments are unknown. We used a canine model to quantify articular cartilage degeneration in the medial compartment of the canine knee, resulting from a surgically created tear or a partial meniscectomy (PM) of the posterior region of the medial meniscus (each group, n = 10). After sacrifice at 12 weeks, the development of gross chondropathy and the changes in cartilage tensile stiffness were quantified, and correlations between these measurements were examined. Both treatment surgical treatment groups caused significantly greater gross chondropathy as compared to the unoperated contralateral controls. Cartilage tensile stiffness was significantly lower than unoperated controls by nearly 28% in both experimental groups. However, there were no significant differences observed between the gross chondropathy or the cartilage mechanical property changes between the experimental groups. Importantly, the severity of gross chondropathy was found to significantly correlate with the decrement in tensile stiffness properties of the articular cartilage. These findings indicate that significant degeneration of canine articular cartilage develops to a similar degree in the presence of a partially healed meniscus tear or a PM of the knee.     

A mechanical comparison of gluteus medius attachment methods in a canine model

Seven techniques of gluteus medius attachment were compared in vitro in a canine model. Four methods were used for tendon to tendon attachment: (a) two modified Bunnell-Mayer stutures, (b) two Kessler locking loop sutures, (c) two horizontal mattress sutures, and (d) two sutures with a looped suture technique. The two methods of tendon to bone attachment were repair with a 1 cm spiked staple and repair with a spiked washer and screw, and the method of bone to bone attachment involved two figure-eight cerclage wires. The colitralateral limb served as a control. Compared with the bone to bone attachment, the four tendon to tendon attachments and the two tendon to bone attachments had significantly less strength (31 and 30% of the ultimate load for bone to bone repair, respectively) and tensile stiffness (24 and 39% of the tensile stiffness for bone to bone attachment, respectively) (p ≤ 0.0001). The control specimens were significantly stronger and stiffer than all specimens (p ≤ 0.05) except those that had bone to bone fixation. There were no significant differences among the four tendon to tendon suture repairs with regard to either strength or stiffness; the values ranged from 28–45% of those of the controls. Among the tendon to bone repairs, fixation with a spiked washer and screw was significantly stronger than that with a spiked staple (p = 0.032), but there was no difference between these two techniques with regard to stiffness.     

Use of a smooth press-fit stem preserves physeal growth after tumor resection

We conducted this study to determine whether the small-diameter, press-fit stem of a novel, noninvasive expandable endoprosthetic device implanted in the limbs of 6 pediatric patients with Stage IIB osteosarcoma affected the growth of the physis through which the stem was inserted. Local control of the tumor necessitated resection of the involved growth plate, and implantation of the device required penetration of the adjacent uninvolved bone, through the growth plate, by the stem of the device. We measured longitudinal growth and the rate of growth of the adjacent uninvolved bone in the salvaged limb and of the equivalent bone in the unoperated contralateral limb. In all cases but one (in which the patient's growth in the contralateral limb appeared complete), longitudinal growth continued in the limb into which the device was implanted: the adjacent uninvolved bone in the salvaged limb grew by an average of 2.4 cm, and the equivalent bone in the unoperated contralateral limb grew by an average of 2.3 cm. We conclude that implantation of a smooth, press-fit stem through the central portion of the uninvolved adjacent physis does not result in growth retardation or arrest.     

Cartilage as an interposition material to prevent transphyseal bone bridge formation: an experimental model

A rabbit model modified from the one originally used by Osterman was used to test the effectiveness of interposition materials in the prevention of epiphyseal-metaphyseal bone bridge formation. Although fat was a moderately effective interposition material, cartilage was more effective in preventing growth retardation and angular deformity of the involved distal femur. None of the interposition materials, however, allowed for completely normal growth. It is theorized that the effectiveness of cartilage may be enhanced by the presence of a factor contained therein which inhibits bone formation.     

A proposed canine model of laparoscopic nonanatomic liver resection

INTRODUCTION: An animal model would be of great use to establish the safety and efficacy of laparoscopic hepatectomy. MATERIALS AND METHODS: A canine model of nonanatomic resection, using low pressure pneumoperitoneum, a variety of dissection and hemostatic techniques, and laparoscopic ultrasonographic vessel identification, was used. We used 20 female dogs: the first 10 were the training group, and the remaining 10 were the evaluation group. RESULTS: In the training group of 10 dogs, 3 of the first 4 developed pneumothorax; this was averted in subsequent cases by disconnecting the ventilator during establishment of pneumoperitoneum. During 2 weeks of postoperative evaluation, intraoperative bleeding required an extended procedure in 1 dog. No other dogs experienced massive intraoperative bleeding. Postoperatively, vital signs and blood hematocrit values showed no bleeding in any dog. Postoperatively, only 2 dogs, as measured by Jackson-Pratt drainage and serum total bilirubin levels, developed bile duct leakage; 1 died due to bacterial peritonitis. Serum aspartate aminotransferase levels corrected within 2 weeks. No emboli were observed in any of the dogs. CONCLUSION: A canine model of laparoscopic hepatectomy is feasible and has readily available monitors for major postoperative complications. Many patients with primary or secondary liver tumors would benefit from limited nonanatomic resection, which seems feasible as less-invasive techniques are improved.     

Spontaneous correction of partial physeal arrest: report of a case and review of the literature

This study describes the rare phenomenon of partial physeal arrest spontaneous correction. It concerns a case of a 3.5-year-old girl who suffered from a Salter-Harris IV fracture of the distal tibial epiphysis, which was managed conservatively. After fracture healing an osseous bridge was formed at the medial part of the physis, leading to a varus deformity. The parents refused the operation, but 6 years later, both the ankle's deformity and the shortening of the extremity had been spontaneously corrected. It seems that the growth potential of the physis healthy portion is able to break the already transformed osseous bridge.     

A mapping method to prepare for surgical excision of a partial physeal arrest

Acquired bony bridging of a physis is best documented by biplane polytomography. Treatment decisions require clear comprehension of the cross-sectional dimensions of the bridge in the transverse plane. This article presents a short practical method for producing a cross-sectional map from the data provided by biplane polytomograms.     

Analysis of lower extremity embolic material after total knee arthroplasty in a canine model

Emboli assumed to consist of fat, marrow, cement, and bone are generated during total knee arthroplasty. This study collected and identified the constituents of the embolic debris and assessed the effects of intramedullary cutting guides in a canine model. During cemented knee arthroplasties with or without the use of intramedullary guides, all embolic debris was collected in a single lobe of lung. In dogs using intramedullary guides, transesophageal echocardiography revealed a sustained embolic shower, and histologically marked amounts of emboli obstructed the pulmonary vasculature. The emboli were composed of fat cells and hematopoietic cells (marrow elements) interspersed with free fat globules. Marrow elements are the primary constituents of the emboli generated during total knee arthroplasty. Intramedullary guides increased debris generation.     

Rotator cuff healing using demineralized cancellous bone matrix sponge interposition compared to standard repair in a preclinical canine model

This Level II study assessed clinically relevant outcomes for repair of large, retracted infraspinatus tendons (ISTs) using a demineralized bone matrix (DBM) sponge (FlexiGraft) hydrated in platelet‐rich plasma (PRP) versus direct repair in a validated canine model. Adult research dogs (n = 10) were used. The IST was transected in each shoulder (n = 20) and randomized to direct repair or repair with DBM‐PRP interposition at 4 weeks posttransection. At 12 weeks postrepair, dogs were sacrificed, and the repair evaluated by magnetic resonance imaging (MRI), histology, and biomechanical testing. MRI and histology scores were significantly (p < 0.05) better in the DBM‐PRP shoulders. Biomechanical testing revealed significantly improved strength of the DBM‐PRP repairs at 5 and 10 mm of displacement, as well as for ultimate failure load. In this canine model of retracted IST repair, DBM‐PRP sponge hydrated in PRP was considered safe and effective. In addition, use of DBM‐PRP was associated with improved MRI and histologic appearance, and improved strength compared to direct repair. Clinical significance: Based on reported failure rates for repair of large, retracted rotator cuff tears, improving tendon‐to‐bone healing is critical. Use of DBM combined with PRP shows potential for addressing this critical clinical need. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:906–912, 2018.

     

双极与单极电切术对犬前列腺组织病理学影响的对比研究

目的:对比研究经尿道前列腺等离子体双极电切术(PKRP)与传统单极前列腺电切术(TURP)术后犬前列腺组织创面凝固层厚度及其病理学的变化。方法:25只成年雄性家犬随机分为3组:PKRP组(12只)、TURP组(12只)和假手术对照组(1只)。于术后0(术后立即)、1、2、8周分别取各组动物处死,获取前列腺标本,光镜下观察前列腺组织病理学改变并测量创面凝固层厚度。结果:术后0、1、2周,PKRP组和TURP组前列腺组织创面的凝固层厚度分别为(237.73±20.12)μm、(113.03±16.65)μm、(106.01±16.36)μm和(200.75±19.34)μm、(129.46±17.81)μm、(116.04±25.67)μm,术后0、1周两组相比,差异有统计学意义(P<0.01)。术后8周,PKRP组和TURP组前列腺组织创面凝固层完全脱落,创面均被覆再生的尿路上皮。术后0、1、2、8周,PKRP组和TURP组前列腺组织均有不同程度的炎症反应,凝固层下部分腺腔扩张,上皮破坏。假手术对照组未见上述变化。结论:PKRP和TURP术对犬前列腺组织创面的病理学影响基本相似。但PKRP术中凝固层厚度大于TURP,提示PKRP术中止血性能可能优于TURP;术后早期,PKRP凝固层较TURP薄,提示PKRP间接的穿透性热损伤可能较TURP小。