Kunihiro Oka

Three-dimensional corrective osteotomy of malunited fractures of the upper extremity with use of a computer simulation system.

BACKGROUND Three-dimensional anatomical correction is desirable for the treatment of a long-bone deformity of the upper extremity. We developed an original system, including a three-dimensional computer simulation program and a custom-made surgical device designed on the basis of simulation, to achieve accurate results. In this study, we investigated the clinical application of this system using a corrective osteotomy of malunited fractures of the upper extremity. METHODS Twenty-two patients with a long-bone deformity of the upper extremity (four with a cubitus varus deformity, ten with a malunited forearm fracture, and eight with a malunited distal radial fracture) participated in this study. Three-dimensional computer models of the affected and contralateral, normal bones were constructed with use of data from computed tomography, and a deformity correction was simulated. A custom-made osteotomy template was designed and manufactured to reproduce the preoperative simulation during the actual surgery. When we performed the surgery, we placed the template on the bone surface, cut the bone through a slit on the template, and corrected the deformity as preoperatively simulated; this was followed by internal fixation. All patients underwent radiographic and clinical evaluations before surgery and at the time of the most recent follow-up. RESULTS A corrective osteotomy was achieved as simulated in all patients. Osseous union occurred in all patients within six months. Regarding cubitus varus deformity, the humerus-elbow-wrist angle and the anterior tilt of the distal part of the humerus were an average of 2 degrees and 28 degrees, respectively, after surgery. Radiographically, the preoperative angular deformities were nearly nonexistent after surgery. All radiographic parameters for malunited distal radial fractures were normalized. The range of forearm rotation in patients with forearm malunion and the range of wrist flexion-extension in patients with a malunited distal radial fracture improved after surgery. CONCLUSIONS Corrective osteotomy for a malunited fracture of the upper extremity with use of computer simulation and a custom-designed osteotomy template can accurately correct the deformity and improve the clinical outcome.

Phase transformation of a zirconia ceramic head after total hip arthroplasty

We report two cases of surface deterioration of a zirconia ceramic femoral head associated with phase transformation after total hip arthroplasty. One head was retrieved at revision due to recurrent dislocation after six years and the other because of failure of the locking mechanism of the polyethylene liner after three years. The monoclinic content of the zirconia ceramics rose from 1% to about 30% on the surface of the heads. SEM revealed numerous craters indicating extraction of the zirconia ceramics at the surface. Surface roughness increased from an initial value of 0.006 microm up to 0.12 microm. This is the first report to show that phase transformation of zirconia ceramics causes deterioration of the surface roughness of the head in vivo after total hip arthroplasty.

Accuracy analysis of three-dimensional bone surface models of the forearm constructed from multidetector computed tomography data

We developed an original computer program that simulates upper limb reconstruction surgery using three‐dimensional (3D) bone models constructed from computed tomography (CT) data. However, the accuracy of a bone model has not been clarified, and radiation exposure from CT scanning posed a concern. The purpose of this study was to investigate the appropriate CT parameters required to reduce radiation exposure while maintaining the accuracy of 3D models of the forearm bones.

Computer-Assisted Corrective Osteotomy for Malunited Diaphyseal Forearm Fractures

BACKGROUND Corrective osteotomy for malunited diaphyseal forearm fractures remains a challenging procedure. We developed a computer-assisted system for corrective surgery, including a three-dimensional simulation program and a custom-made osteotomy template, and investigated the results of corrective surgery for malunited diaphyseal forearm fractures with use of this technology. METHODS Twenty patients (fifteen male patients and five female patients) with malunited diaphyseal forearm fractures were managed with three-dimensional corrective osteotomy with a custom-made osteotomy template based on computer simulation. We performed osteotomy of both radius and ulna in fourteen patients and osteotomy of the radius alone in six patients. The median age at the time of surgery was eighteen years (range, eleven to forty-three years). The median duration between the time of injury and the time of surgery was thirty-three months (range, five to 384 months). The minimum duration of follow-up was twenty-four months (median, twenty-nine months; range, twenty-four to forty-eight months). To evaluate the results, we compared preoperative and postoperative data from radiographs, forearm motion, grip strength, and pain. RESULTS The average radiographic deformity angle preoperatively was 21° (range, 12° to 35°) compared with the normal arm; the radiographic deformity angle was improved to 1° (range, 0° to 4°) postoperatively. The distal radioulnar joints of both sides were symmetric on postoperative radiographs regarding the relative lengths of the radius and ulna. In eighteen patients who had a restricted range of forearm motion preoperatively, the mean arc of forearm motion improved from 76° (range, 25° to 160°) preoperatively to 152° (range, 80° to 180°) postoperatively (p < 0.01). However, forearm supination was still restricted by ≥ 70° in three patients who had been younger than ten years old at the time of the initial injury and who had long-standing malunion for ninety-six months or longer. Painful recurrent dislocation of the distal ulna or radial head resolved or decreased in five patients. Average grip strength improved from 82% to 94% compared with that of the contralateral, normal side. CONCLUSIONS Computer-assisted osteotomy can provide excellent radiographic and clinical outcome for the treatment of malunited diaphyseal forearm fractures. Satisfactory restoration of forearm motion can be achieved even in relatively long-standing cases in adults.

Corrective Osteotomy for Malunited Intra-Articular Fracture of the Distal Radius Using a Custom-Made Surgical Guide Based on Three-Dimensional Computer Simulation: Case Report

We report a case of malunited intra-articular fracture of the distal radius successfully treated with corrective osteotomy through an extra-articular approach using a custom-made surgical guide that was designed based on preoperative three-dimensional computer simulation.

The in vivo isometric point of the lateral ligament of the elbow.

BACKGROUND Many reports have discussed reconstruction of the lateral ulnar collateral ligament for the treatment of posterolateral rotatory instability of the elbow, but information regarding the isometric point of the lateral ligament of the elbow is limited. The purposes of the present study were to investigate the in vivo and three-dimensional length changes of the lateral ulnar collateral ligament and the radial collateral ligament during elbow flexion in order to clarify the role of these ligaments as well as to identify the isometric point for the reconstructed lateral ulnar collateral ligament on the humerus where the grafted tendon should be anchored. METHODS We studied in vivo and three-dimensional kinematics of the normal elbow joint with use of a markerless bone-registration technique. Magnetic resonance images of the right elbows of seven healthy volunteers were acquired in six positions between 0 degrees and 135 degrees of flexion. We created three-dimensional models of the elbow bones, the lateral ulnar collateral ligament, and the radial collateral ligament. The ligament models were based on the shortest calculated paths between each origin and insertion in three-dimensional space with the bone as obstacles. We calculated two types of three-dimensional distances for the ligament paths with each flexion position: (1) between the center of the capitellum and the distal insertions of the ligaments (to investigate the physiological change in ligament length) and (2) between eight different humeral origins and the one typical insertion of the lateral ulnar collateral ligament (to identify the isometric point of the reconstructed lateral ulnar collateral ligament). RESULTS The three-dimensional distance for the lateral ulnar collateral ligament was found to increase during elbow flexion, whereas that for the radial collateral ligament changed little. The path of the lateral ulnar collateral ligament gradually developed a detour because of the osseous protrusion of the lateral condyle with flexion. The most isometric point for the reconstructed lateral ulnar collateral ligament was calculated to be at a point 2 mm proximal to the center of the capitellum. CONCLUSIONS The radial collateral ligament is essentially isometric, but the lateral ulnar collateral ligament is not. The lateral ulnar collateral ligament is loose in elbow extension and becomes tight with elbow flexion.

Change in the Length of the Ulnocarpal Ligaments During Radiocarpal Motion: Possible Impact on Triangular Fibrocartilage Complex Foveal Tears

PURPOSE The fovea of the ulnar head is the primary attachment site for both the distal radioulnar and the ulnocarpal ligaments. Thus, both ligaments should be simultaneously affected by the traumatic avulsion of the triangular fibrocartilage complex from its ulnar attachment. Little attention, however, has been directed toward the role of the ulnocarpal ligaments in the mechanics of this type of injury. The purpose of this study was to investigate the changes in length of the ulnocarpal ligaments during various radiocarpal motions and to determine the type of radiocarpal motion that makes the ulnocarpal ligament taut and that could cause foveal avulsion if it were excessive. METHODS The 3-dimensional kinematics of the wrist joint were investigated noninvasively using a markerless bone registration technique in vivo. Magnetic resonance images of the wrists of 15 healthy volunteers were acquired in at least 5 positions during each wrist flexion-extension motion, radioulnar deviation, or the so called dart-throwing motion (radial extension-ulnar flexion motion). The 3-dimensional ligament paths of the ulnotriquetral, ulnolunate, ulnocapitate, and palmar radioulnar ligaments were modeled as the shortest paths between the fovea and the insertion point of each ligament. Changes in the 3-dimensional ligament length of each ligament between the neutral position and each wrist position were then calculated. RESULTS The lengths of the ulnotriquetral and ulnocapitate ligaments increased the most on wrist radial extension, and the length of the ulnolunate ligament increased the most on wrist extension. The length of the palmar radioulnar ligament changed minimally during any motion. CONCLUSIONS The ulnocarpal ligaments are likely to be stretched tensely in wrist radial extension and wrist extension. This study supports the hypothesis that one of the mechanisms responsible for a triangular fibrocartilage complex foveal tear is excessive traction of the ulnocarpal ligament caused by a fall on the outstretched hand.

Preoperative, Computer Simulation-based, Three-dimensional Corrective Osteotomy for Cubitus Varus Deformity with Use of a Custom-designed Surgical Device

BACKGROUND Cubitus varus deformity after a supracondylar fracture classically includes varus, extension, and internal rotation components. However, to our knowledge, no reliable surgical method for three-dimensional corrective osteotomy has been established. We developed an intraoperative guide system involving a custom-made surgical template designed on the basis of a three-dimensional computer simulation incorporating computed tomography (CT) data. We aimed to investigate the feasibility of this novel technique for correcting cubitus varus deformity. METHODS Thirty consecutive patients (twenty-three males and seven females) with a cubitus varus deformity resulting from the malunion of a distal humeral supracondylar fracture were included in this study. Between October 2003 and May 2011, the patients underwent a three-dimensional corrective osteotomy with use of a custom-made surgical template. The patients were then followed for a minimum of twelve months. We evaluated radiographic parameters, including the humerus-elbow-wrist angle and tilting angle, as well as the ranges of motion of the elbow and shoulder at the time of the most recent follow-up. An overall clinical evaluation was performed. RESULTS Bone union was achieved at a mean of four months after surgery. The mean humerus-elbow-wrist angle and tilting angle on the affected side improved significantly from 18.2° (varus) and 25.0°, respectively, before surgery, to 5.8° (valgus) and 38.0°, respectively, after surgery. Hyperextension of the elbow and internal rotation of the shoulder were normalized in all patients. Early plate breakage was observed in one patient. One patient had mild recurrence of varus deformity. Twenty-seven patients had an excellent result, three had a good result, and none had a poor result. CONCLUSIONS Three-dimensional corrective osteotomy with the use of a custom-made surgical template that is designed and produced on the basis of computer simulation is a feasible and useful treatment option for cubitus varus deformity.

Corrective osteotomy using customized hydroxyapatite implants prepared by preoperative computer simulation

Opening wedge corrective osteotomy usually requires a bone graft. However, it is difficult to shape the graft into an appropriate configuration. To resolve this problem, we developed an original computer program system that calculates the size and shape of a bone graft and cuts a hydroxyapatite block into the desired shape.

3-Dimensional Prebent Plate Fixation in Corrective Osteotomy of Malunited Upper Extremity Fractures Using a Real-Sized Plastic Bone Model Prepared by Preoperative Computer Simulation

PURPOSE To assess the clinical outcome and accuracy of prebent plate fixation in corrective osteotomy for malunited upper extremity fractures using a plastic bone model manufactured by preoperative computer simulation. METHODS Nine consecutive patients underwent computed tomography (CT)-based 3-dimensional corrective osteotomy for malunited upper extremity fractures. There were 4 cubitus varus deformities, 1 cubitus valgus deformity, and 4 forearm diaphyseal malunions. We constructed a computer model of the affected bones using the CT data and simulated the 3-dimensional deformity correction on a computer. A real-sized plastic model of the corrected bone was manufactured by rapid prototyping. We used a metal plate, prebent to fit the plastic bone model, in the actual surgery. Patients were evaluated after an average follow-up of 22 months (range, 14-36 mo). We retrospectively collected radiographic and clinical data at the most recent follow-up and compared them with preoperative data. We also performed CT after surgery and evaluated the error in corrective osteotomy as the difference between preoperative simulation and postoperative bone model. RESULTS The range of forearm rotation and grip strength in patients with forearm malunions improved after corrective osteotomies of the radius and ulna. Wrist pain, which 2 patients with forearm malunion had experienced before surgery, disappeared or decreased substantially after surgery. Radiographic examination indicated that preoperative angular deformities were nearly nonexistent after all corrective osteotomies. Three-dimensional errors in the corrective osteotomy using a prebent plate, as evaluated by CT data, were less than 3 mm and 2°. CONCLUSIONS Prebent plate fixation in corrective osteotomy for malunited upper extremity fractures using a 3-dimensionally corrected, real-sized plastic bone model prepared by preoperative computer simulation is a precise and relatively easily performed technique that results in satisfactory clinical outcome. TYPE OF STUDY/LEVEL OF EVIDENCE Therapeutic IV.