Thossart Harnroongroj

The talar body prosthesis.

Arthrodesis or talectomy for the treatment of avascular necrosis of the talus or a severe crush fracture of the body of the talus often produces a disability of the ankle and the foot. Therefore, a prosthesis designed to replace the body of the talus and to preserve the function of the ankle and the foot was developed. The prosthesis has a superior curved surface, and the medial and lateral surfaces are inclined for articulation with the tibia and the fibula. The inferior aspect has a concave curved surface at the posterior aspect of the prosthesis to serve as the posterior facet for articulation with the posterior facet of the calcaneus, and there is a convex curved surface at the anterior aspect of the prosthesis for articulation with the middle facet of the calcaneus. The neck and the head of the talus are preserved to allow insertion of the prosthetic stem into bone. A transmedial malleolar approach is used for insertion of the prosthesis. We inserted the talar body prosthesis in sixteen patients—twelve who had avascular necrosis of the talar body and four who had a severe crush fracture of the talar body—between 1974 and 1990. Three patients who were evaluated five years postoperatively had a satisfactory result, and one patient had failure of the prosthesis at eight months because the diameter of the inferior concave curved surface was too small in the region of the posterior facet and had caused erosion of the posterior facet of the calcaneus. All three patients who were evaluated six to ten years postoperatively had a satisfactory result. All except one of the nine patients who were evaluated eleven to fifteen years postoperatively had a satisfactory result; the exceptional patient had an unsatisfactory result because the prosthetic stem had sunk into the talar neck. This patient had a revision thirteen years after the index operation. We believe that the talar body prosthesis can be used to replace the body of a talus with avascular necrosis or a severe crush fracture, thus maintaining the function of the ankle and the foot for a prolonged period.

Biomechanical aspects of plating osteosynthesis of transverse clavicular fracture with and without inferior cortical defect

OBJECTIVE: To find out whether superior or anterior plating osteosynthesis of clavicular fractures with and without inferior cortical defect provides more stability. DESIGN: The bearing of maximal bending moment of the osteosyntheses was determined by applying a load from a universal testing machine. BACKGROUND: A plate is recommended for internal fixation of the clavicular fracture. Stability of the osteosynthesis depends on placing of the plate at anterior or superior aspect of the clavicle. Whereas, the pattern of the fracture also influences stability. METHODS: Pairs of fresh cadaveric clavicles were used. The fractures were created at middle clavicle. Both superior and anterior plating fixation of both patterns of the fractures were performed. A compression load was applied at lateral end of the clavicle and maximal bending moment was calculated. RESULTS: For fractures without inferior cortical defect, the superior plating could withstand 12.05 (SD, 1.74) Nm and 8.69 (SD, 1.56) Nm for the anterior plating. For the fractures with inferior cortical defect, the superior plating could withstand 7.87 (SD, 2.58) Nm, but 10.26 (SD, 2.19) Nm for the anterior plating. CONCLUSIONS: The superior plating of the fracture without inferior cortical defect provides more stability against the bending moment than the anterior plating (P = 0.008). Whereas, the anterior plating of the fracture with inferior cortical defect provides more stability (P = 0.025). RELEVANCE: When plating a clavicular fracture without inferior cortical defect is performed, the plate should be placed at superior aspect of the clavicle for achieving more stability of the osteosynthesis against the bending moment. On the other hand, when the fracture has an inferior cortical defect, the plate should be placed at the anterior aspect of the clavicle.

Lipid peroxidation, glutathione, vitamin E, and antioxidant enzymes in synovial fluid from patients with osteoarthritis.

Aim:  To compare levels of lipid peroxidation and antioxidants in synovial fluid from primary knee osteoarthritis (OA) patients with severe cartilage damage undergoing total knee replacement with those in the synovial fluid from injured knee joint patients with intact cartilage undergoing knee arthroscopy.

Roof-arc angle and weight-bearing area of the acetabulum

BACKGROUND Unreduced fracture crossing the weight-bearing dome of the acetabulum leads to arthritis. Thus the integrity of the weight-bearing dome is considered to be an important prognostic indicator for acetabular fracture. The decision of whether or not to operate is based on the location of the fracture relative to the weight-bearing dome. A displaced fracture crossing the weight-bearing dome is an indication for surgery. OBJECTIVE To measure the medial, anterior, and posterior roof-arc angles that cross the weight-bearing dome. METHODS Twenty cadeveric hip joints were dissected and simulated transverse fractures of acetabuli through the transtectal area were made. The radiographic examinations were taken in three views: AP, obturator oblique, and iliac oblique. Roof-arc angle was measured in all three views (medial, anterior, and posterior). RESULTS The medial roof-arc angle was 46+/-6.3 degrees , anterior roof-arc angle was 52+/-7.0 degrees , and posterior roof-arc angle was 62 degrees +/-8.5 degrees . CONCLUSIONS In acetabular fracture, a medial roof-arc angle less than 46 degrees , an anterior roof-arc angle less than 52 degrees , or posterior roof-arc angle less than 61 degrees is considered to be involved in a weight-bearing area. CLINICAL RELEVANCE These roof-arc angle values may be used as a surgical guideline for an acetabular fracture around the weight-bearing area.

Major risk factors for the second contralateral hip fracture in the elderly

OBJECTIVES The purpose of this study was to determine which of the predisposing risk factors for the first hip fracture would continue to be effective for the development of the second hip fracture in the elderly. METHODS Data of 125 patients (31 men, 94 women) aged 55 years or older were evaluated, who sustained first (group 1, n=97) and second contralateral (group 2, n=28) hip fracture. Patients who were treated with bisphosphonate, calcitonin, and estrogen were not included. RESULTS The incidence of the second hip fracture was higher (78.6%) beyond 12 months of the first fracture. The risk for sustaining a second hip fracture was 3.96-fold greater in patients over 85 years of age (p<0.05). Among comorbid medical conditions, eye diseases (p=0.02) and neurological diseases (p=0.048) were significantly more frequent in group 2. There was an obvious relationship between the second hip fracture and lower Singh index grades of = or < 3 (p<0.001). Patients over 85 years of age and having a lower Singh index grade were found to have a 6.57-fold increased risk for developing a second hip fracture (95% CI: 2.13-20.3; p=0.001). In univariate analysis, neurological diseases represented a significantly increased risk. Eye diseases were highly associated with an increased risk for second hip fractures in univariate (OR: 3.3, 95% CI: 1.2-9.2, p=0.020) and multivariate (OR: 7.6, 95% CI: 1.9-30.7, p=0.004) analyses. The Singh index of grade = or < 3 showed the highest associations with second hip fractures in both univariate (OR: 18.9, 95% CI: 5.8-65.9, p<0.001) and multivariate (OR: 30.00, 95% CI: 7.9-112.9, p<0.001) analyses. CONCLUSION We concluded that, of all the risk factors for the first hip fractures, only hypotrophic changes in the proximal femoral trabeculae, eye diseases, and neurological diseases acted as major risk factors for the second contralateral hip fractures in the elderly.

Intramedullary pin fixation in clavicular fractures: A study comparing the use of small and large pins

The S-shaped clavicle poses a problem for intramedullary pin fixation. Stability of fracture fixation is closely related to the length of intramedullary pin engagement. This study was carried out to determine the engagement length of intramedullary pins into clavicular fractures using a small and a large pin. Seven pairs of fresh cadaveric clavicles were prepared and arranged into Group 1 and Group 2 for paired study. A mid-third clavicular fracture was created at the junction of the two curves of the clavicle. In Group 1, a 3.2 mm diameter threaded Steinman pin was introduced into the medullary canal of the clavicle by retrograde technique and the medial fragment of the fracture was drilled until the pin perforated the bone cortex. In Group 2, a 4 mm diameter threaded Steinman pin was used in the same manner. The results showed that Group 1 had an average engagement of pin into the clavicle of 9.11 cm with a ratio to total length of the clavicle of 0.59. In Group 2, the average engagement length into the clavicle was 7.17 cm with a ratio of 0.47. The difference was significant, with the smaller pin providing better fixation. The pins in both groups perforated the lateral fragment at the posterosuperior aspect and the medial fragment at the anterior aspect of the clavicle. The angle that the pin made with the long axis of the clavicle in Group 1 was 22.43° and in Group 2, 26.57°. Although the 3.2 mm diameter pin was more aligned to the long axis of the clavicle than the 4 mm diameter pin, the difference was not significant.

Determination of the role of the cancellous bone in generation of screw holding power at metaphysis.

OBJECTIVE To determine whether cancellous bone at metaphysis plays a significant role in generation of holding power of the cancellous screw. DESIGN Maximal holding power of the cancellous screw at distal metaphysis of the femur with and without cancellous bone inside was determined by applying a load to push out the screw. BACKGROUND Generation of screw holding power from the cancellous bone can arise by a mechanism of compression of cancellous bone between screw threads when a screw is inserted by non-tapping technique. Metaphysis has intermediate amount of cancellous and cortical bone when compared with diaphysis and intercondyle of a long bone. METHODS Eight pairs of fresh cadaveric femurs were used. One femur of a pair was removed of cancellous bone at the distal metaphysis; cancellous bone of the other was preserved. A full thread cancellous screw was inserted into the distal femoral metaphysis. An axial load was applied at the screw tip to push out the screw by using a universal testing machine. RESULT Mean push-out force of the screw at distal femoral metaphysis without cancellous bone inside was 1824.76 N and stiffness was 746.76 N/mm. Mean push-out force of the screw at distal femoral metaphysis with preservation of cancellous bone was 2015.86 N and stiffiness was 853. 09 N/mm. The statistical analysis of both groups showed no significant differences. CONCLUSIONS This study confirmed that cancellous bone at metaphysis plays no significant role in generation of holding power of the cancellous screw. RELEVANCE Because metaphyseal cancellous bone plays no role in generation of screw holding power, only a well-inserted cancellous screw into bone cortices can achieve good screw holding power at metaphysis of a long bone.

The Talar Body Prosthesis: Results at Ten to Thirty-six Years of Follow-up

BACKGROUND Satisfactory results of implantation of the talar body prosthesis were reported in 1997, although some complications associated with the initial design were noted. The present study evaluated outcomes of treatment with a modified talar body prosthesis. METHODS Of the thirty-six talar body prostheses implanted with use of a transmalleolar surgical approach from 1974 to 2011, thirty-three were available for follow-up at ten to thirty-six years or had failed prior to that time. The indication for implantation had been osteonecrosis in twenty-three patients, a comminuted talar fracture in eight, and a talar body tumor in two. RESULTS Twenty-eight of the thirty-three prostheses were still in place at the time of final follow-up and five had failed prior to five years. The duration of follow-up was ten to twenty years in eight patients, twenty to thirty years in eleven, and thirty to thirty-six years in nine. The AOFAS (American Orthopaedic Foot & Ankle Society) ankle-hindfoot score did not differ significantly among these three groups. Patients over sixty-five years of age with underlying disease that impeded walking ability had lower AOFAS scores. Early prosthesis failure occurred as a result of size mismatch in two patients, tumor recurrence in one, infection in one, and osteonecrosis of the talar head and neck in one. These failures, which occurred at eight to fifty-seven months, were treated with tibiotalar arthrodesis in three patients, prosthesis revision in one, and below-the-knee amputation in one. CONCLUSIONS Although early prosthesis failure may occur, survival of the talar body prosthesis can provide satisfactory ankle and foot function. LEVEL OF EVIDENCE Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

An aiming device for pin fixation at the iliac crest for external fixation in unstable pelvic fracture

To improve the accuracy of pinning at the iliac crest during external fixation of the pelvic fracture, an aiming device has been designed. The device consists of 3 parts: a sleeve which accommodates a 5.0 Shanz pin, a handle and guide points. The guide points were designed to grasp the iliac crest to allow proper pin fixation. The device has undergone trials to fix Shanz pins on the iliac crests of 10 cadavers by 10 recently graduated doctors. All pins were fixed in proper position and passed into the bone between the two tables of the iliac crest without penetrating the tables. The device has so far been used in 50 patients who had unstable pelvic fractures. All pins were in the proper positions and there had been no loosening at the time the pins were removed. The use of this aiming device for pinning the iliac crest for external fixation of pelvic fracture has given encouraging results.

A retrospective analysis of medial opening wedge high tibial osteotomy for varus osteoarthritic knee.

Background: Medial opening wedge high tibial osteotomy (MOWHTO) has proven to be an effective treatment for varus osteoarthritic knees. Various methods of fixation with different implant types and using either bone grafts or bone substitutes have been reported. We performed non-locking T-buttress plate fixation with autologous iliac bone graft augmentation, which is defined here as the traditional method, and locking compression plate fixation without any bone graft or bone substitute. We aimed to compare bone union and complications of these two MOWHTO techniques. Materials and Methods: Between June 2005 and December 2007, 50 patients who underwent MOWHTO (a total of 60 knees) were retrospectively reviewed and classified into two groups: group A, which consisted of 26 patients (30 knees) was treated using T-buttress plate fixation with autologous iliac bone graft augmentation and group B, which consisted of 24 patients (30 knees) was operated upon using a medial high tibial locking compression plate without any augmentation. Demographic characteristics and radiographic outcomes, including union rate, time to union, medial osteotomy defects, and complications, were collected and compared between the two groups. The progress of all patients was followed for at least 2 years. Results: All osteotomies united within 12 weeks after surgery. Group B had slightly longer time to union than group A (10.3 weeks and 9.5 weeks, respectively; P = 0.125). A significantly higher incidence of medial defects after osteotomy was reported in the locking compression plate group (P = 0.001). A total of 5 (8.3%) knees had complications. In group A, one knee had a superficial wound infection and another knee had a lateral tibial plateau fracture without significant loss of correction. In group B, one knee had screw penetration into the knee joint and two knees had local irritation that required the removal of the hardware. Conclusion: Locking compression plate fixation without the use of bone grafts or bone substitutes provides a satisfactory union rate and an acceptable complication rate when compared to the traditional MOWHTO technique. Thus, we recommend using this technique for treating unicompartmental medial knee osteoarthritis.