Summary

A novel in vivo animal model to establish new surgical interventions for patients with ACL insufficiency.

Summary Statement

We measured scapulothoracic motions during humeral abduction with different humeral rotations in healthy subjects and whole cadaver models and clarified that humeral rotation significantly influenced scapular kinematics.

Although proximal tibia vara is physiologically and pathologically observed, it is difficult to measure the varus angle accurately and reproducibly due to inaccuracy of the radiograph because of rotational and/or torsional deformities. Since tibial coronal alignment in TKA gives influence on implant longevity, intra- or extra-medurally cutting guide should be set carefully especially in cases with severe tibia vara. In this context, we measured the proximal tibial varus angle by introducing 3D-coordinate system.

We investigated the characteristics of patients who achieved Japanese-style deep flexion (seiza-sitting) after total knee replacement (TKR) and measured three-dimensional positioning and the contact positions of the femoral and tibial components. Seiza-sitting was achieved after surgery by 23 patients (29 knees) of a series of 463 TKRs in 341 patients. Pre-operatively most of these patients were capable of seiza-sitting, had a lower body mass index and a favourable attitude towards the Japanese lifestyle (27 of 29 knees). According to two-/three-dimensional image registration analysis in the seiza-sitting position, flexion, varus and internal rotation angles of the tibial component relative to the femoral component had means of 148° (sd 8.0), 1.9° (sd 3.2) and 13.4° (sd 5.9), respectively. Femoral surface contact positions tended to be close to the posterior edge of the tibial polyethylene insert, particularly in the lateral compartment, but only 8.3% (two of 24) of knees showed femoral subluxation over the posterior edge. The mean contact positions of the femoral cam on the tibial post were located 7.8 mm (sd 1.5) proximal to the lowest point of the polyethylene surface and 5.5 mm (sd 0.9) medial to the centre of the post, indicating that the post-cam contact position translated medially during seiza-sitting, but not proximally. Collectively, the seiza-sitting position seems safe against component dislocation, but the risks of posterior edge loading and breakage of the tibial polyethylene post remain.

Cite this article: Bone Joint J 2013;95-B:782–7.

Purpose

The frequency of venous thrombo-embolism (VTE) after total hip arthroplasty(THA) is 20–30% and it is serious complication under THA. Therefore it is necessary to detect and prevent VTE. The purpose of this study were examined the frequency of VTE and the factor of incidence of VTE in our hospital.

Introduction

The goal of total hip arthroplasty (THA) should be to reconstruct the acetabulum by positioning the hip center as close as possible to the anatomical hip center. However, the true position of the anatomic hip center can be difficult to determine during surgery on an individual basis. In 2005, we designed, produced an acetabular reaming guide, and clinically used to enable cup placement in the ideal anatomical position. This study was examined the accuracy the reaming guide for THA in prospective study.

Although optimal alignment is essential for improved function and implant longevity after TKA, we have less bony landmarks of tibia relative to femur. Trans-malleolar axis (TMA) is a reference line of distal tibia in the axial plane, which externally rotated relative to a ML axis of proximal tibia. We originally defined another reference axis associated with the orientation of tibial plafond, and then measured tibial torsion in the 3D-coordinate system.

Three-dimensional CAD models of 20 tibiae were reconstructed based on pre-operative CT data from OA patients (16 females and 4 males, 73.8 ± 6.9 years old). TMA was a line connecting each apex of medial and lateral malleolus. The plafond axis (PLA) that we originally defined in this study was a line connecting each midpoint of medial and lateral margin of talocrural facet. In terms of interobserver correlation coefficiency and mean errors of the designated points to define those axes, TMA was found out to be 0.982, 3.14 ± 0.47 mm (medial), and 0.988, 4.88 ± 0.59 mm (lateral). Those of PLA were 0.997, 1.97 ± 0.53 mm (medial), and 0.995, 2.02 ± 0.44 mm (lateral). The tibial torsion was 16.3 ± 6.3°with reference to TMA, and 10.2 ± 8.4°to PLA.

Based on these results, as for the rotational reference axis in the axial plain of distal tibia, we consider the plafond axis to be another reliable and reproducible axis, which is expected to be applicable in preoperative planning in TKA to reduce outliers of coronal alignment.

We conducted a prospective follow-up MRI study of originally asymptomatic healthy subjects to clarify the development of Modic changes in the cervical spine over a ten-year period and to identify related factors. Previously, 497 asymptomatic healthy volunteers with no history of cervical trauma or surgery underwent MRI. Of these, 223 underwent a second MRI at a mean follow-up of 11.6 years (10 to 12.7). These 223 subjects comprised 133 men and 100 women with a mean age at second MRI of 50.5 years (23 to 83). Modic changes were classified as not present and types 1 to 3. Changes in Modic types over time and relationships between Modic changes and progression of degeneration of the disc or clinical symptoms were evaluated. A total of 31 subjects (13.9%) showed Modic changes at follow-up: type 1 in nine, type 2 in 18, type 3 in two, and types 1 and 2 in two. Modic changes at follow-up were significantly associated with numbness or pain in the arm, but not with neck pain or shoulder stiffness. Age (≥ 40 years), gender (male), and pre-existing disc degeneration were significantly associated with newly developed Modic changes.

In the cervical spine over a ten-year period, type 2 Modic changes developed most frequently. Newly developed Modic changes were significantly associated with age, gender, and pre-existing disc degeneration.

In the light of the increasing popularity of femoral resurfacing implants, there has been growing concern regarding femoral neck fracture. This paper presents a detailed investigation of femoral neck anatomy, the knowledge of which is essential to optimise the surgical outcome of hip resurfacing as well as short hip stem implantation.

Three-dimensional lower limb models were reconstructed from the CT-scan data by using the Mimics (Materialise NV, Leuven, Belgium). We included the CT data for 22 females and nine males with average age of 60.7 years [standard deviation: 16.4]. A local coordinate system based on anatomical landmarks was defined and the measurements were made on the unaffected side of the models.

First, the centre of the femoral head was identified by fitting an optimal sphere to the femoral head surface. Then, two reference points, one each on the superior and the inferior surface of the base of femoral neck were marked to define the neck resection line, to which an initial temporary neck axis was set perpendicular. Cross-sectional contours of the cancellous/cortical border were defined along the initial neck axis. For each cross-sectional contour, a least-square fitted ellipse was determined. The line that connects the centre of the ellipse at the base of the femoral neck and the centre of the femoral head was defined as the new neck axis. The above process was repeated to reduce variances in the estimation of the initial neck axis. The neck isthmus was identified according to the axial distributions of the cross-sectional ellipse parameters.

The short axis of the ellipse decreased monotonically since it was calculated from the center of the femoral head to the neck resection level (base of neck), whereas the long axis changed with the local minima. The cross section at which the long axis of the fitted ellipse had the local minima was determined as the neck isthmus.

The following measurements were made on the proximal part of the femur. The neck axis length measured from the center of the femoral head to the lateral endosteal border of the proximal femur was 67.3 mm [6.4]. The length between the center of the femoral head and the neck isthmus was 22.5 mm [2.7]. The diameter of the ellipse long axis at the neck isthmus was 27.6 mm [3.5] and was 23.6 mm [3.3] for the short axis.

The center of the neck isthmus did not align with the neck axis. The deviation of the isthmus from the neck axis which we defined as the isthmus offset was 0.7 mm [0.4].

If an alternative neck axis was defined between the center of the femoral head and the center of the neck isthmus, there would be a certain degree of angular shift with respect to the original neck axis. An angular shift of 1.8 degrees between the two axes can be expected for a 0.7-mm isthmus offset. In the worst case, an angular shift of 4.59 degrees was estimated for a subject with the largest isthmus offset of 1.93 mm.

Further investigations would be necessary to determine the axis configuration that represents the clinically relevant centre of the femoral neck. In order to reduce the deviations in the three-dimensional determination of the femoral neck axis, the reference anatomical landmarks and methods of evaluation should be carefully selected.

We have reviewed 38 surgically treated cases of spontaneous posterior interosseous nerve palsy in 38 patients with a mean age of 43 years (13 to 68) in order to identify clinical factors associated with its prognosis. Interfascicular neurolysis was performed at a mean of 13 months (1 to 187) after the onset of symptoms. The mean follow-up was 21 months (5.5 to 221). Medical Research Council muscle power of more than grade 4 was considered to be a good result. A further 12 cases in ten patients were treated conservatively and assessed similarly.

Of the 30 cases treated surgically with available outcome data, the result of interfascicular neurolysis was significantly better in patients < 50 years old (younger group (18 nerves); good: 13 nerves (72%), poor: five nerves (28%)) than in cases > 50 years old (older group (12 nerves); good: one nerve (8%), poor: 11 nerves (92%)) (p < 0.001). A pre-operative period of less than seven months was also associated with a good result in the younger group (p = 0.01). The older group had a poor result regardless of the pre-operative delay.

Our recommended therapeutic approach therefore is to perform interfascicular neurolysis if the patient is < 50 years of age, and the pre-operative delay is < seven months. If the patient is > 50 years of age with no sign of recovery for seven months, or in the younger group with a pre-operative delay of more than a year, we advise interfascicular neurolysis together with tendon transfer as the primary surgical procedure.

We present a case of post-traumatic osteonecrosis of the radial head in a 13-year-old boy which was treated with costo-osteochondral grafts. A satisfactory outcome was seen at a follow-up of two years and ten months.

Although costo-osteochondral grafting has been used in the treatment of defects in articular cartilage, especially in the hand and the elbow, the extension of the technique to manage post-traumatic osteonecrosis of the radial head in a child has not previously been reported in the English language literature. Complete relief of pain was obtained and an improvement in the range of movement was observed. The long-term results remain uncertain.

The purpose of this study was to investigate the effect of knee flexion contracture on trunk kinematics.

Ten healthy old women, averaged sixty-two years, participated in this study. Subjects were tested at our laboratory with use of gait analysis system which consisted of eight retro-reflective markers (placed at bilateral acromion, anterior and posterior superior iliac spine, and iliaccrest), and five cameras. Unilateral (only right side) knee flexion contractures of zero, fifteen, and thirty degrees were simulated with a hard brace. All subjects performed walking trials at their preferred speed with or without simulation. First, level walking was measured without simulation, and then, with simulation at zero, fifteen and thirty degrees of flexion in order. Walking trials without brace was used as control. We evaluated walking velocity (m/s) and trunk kinematics (degrees). In the coronal plane, shoulder-pelvis bending angle was defined as the angle between shoulder girdle line and pelvic line. In the sagittal plane, anterior inclination of the trunk was defined by the slope linked right acromion and iliac crest, and anterior inclination of the pelvis was defined by the slope linked right superior anterior iliac spine and right superior posterior iliac spine. Shoulder-pelvis rotation angle was defined as the angle between shoulder girdle line and pelvic line in the axial plane. Maximum values were calculated.

Walking velocity was significantly decreased at thirty degrees contracture (1.19 at controls, 0.98 at thirty degrees contracture). In the coronal plane, trunk significantly tilted leftward rather (4.5) than rightward (1.8) at thirty degrees contracture. In the sagittal plane, trunk anterior inclination significantly increased at thirty degrees contracture (0.1 at controls, 3.1 at thirty degrees contracture). However, pelvic anterior inclination was similar. In the axial plane, trunk significantly rotated rightward (6.7) rather than leftward (4.3) at thirty degrees contracture.

Knee flexion contracture significantly influences physiological trunk kinematics in each plane. In particular, lateral bending to the contracture side was restricted, and this fact indicated that the lumbar spine may bend convexly to knee contracture side. These facts may result in Knee-Spine Syndrome.

Purpose: The purpose of this study was to investigate the relationship between knee flexion contracture and spinal alignment.

Methods: Ten healthy women (mean age 62) participated in this study. Subjects were examined with posture analysis system, using twelve retro-reflective markers (placed at bilateral acromion, bilateral anterior and posterior superior iliac spine, iliaccrest, greater trochanter, lateral knee joint, lateral malleolus, lateral calcaneus, and fifth metatarsal head), five cameras and a force plate. Unilateral (only right side) knee flexion contractures were simulated by using a hard brace at 0, 15 and 30 degrees. First, relaxed standing was measured without simulation, and then the same measurement was performed with each simulation. The posture without brace was used as control. The shoulder tilting angle was defined by the height difference in right and left acromions. The pelvic tilting angle was defined by the height difference in right and left superior posterior iliac spines. The anterior-bent of the trunk was defined by the slope linked right acromion and right iliac crest. The posterior-bent of the pelvis was defined by the slope linked right superior anterior iliac spine and right superior posterior iliac spine. Knee resultant force (% body weight) was calculated by using inverse dynamics technique.

Results: When contracture angle increased, the trunk was significantly tilted leftward (1.4 degrees at 30 degrees contracture), and the pelvis was significantly tilted rightward (1.8 degrees at 30 degrees contracture). In anterior-bent of the trunk, no significant difference was detected. The posterior-bent of the pelvis was significantly increased (1.5 degrees at 30 degrees contracture). The severer the right knee contracture, the smaller the right knee resultant force (41.5 at controls, 28.7 at 30 degrees contracture) and the larger the left knee resultant force (40.2 at controls, 59.9 at 30 degrees contracture).

Conclusions: This study showed the influence of knee flexion contracture not only in the sagittal plane, as the previous study reported, but also in the coronal plane. Severe unilateral knee flexion contracture can cause the lumbar spine bent convexly to the contracture side. This may result in Knee-Spine Syndrome.

We have developed lameller etched titanium (L.E.T.) structure, as a new bone-prosthesis interface. L.E.T. has a laminating structure consisting of a thin board made of porous etched titanium layer. We call this structure, a space controlled interface, because its pore shape, pore size and porosity within the interface can be controlled easily.

Purpose: We compared the binding capacity of L.E.T. system with the conventional beads surface, by experimental study.

Materials and Methods: We implanted two types of interface in 30 canine femora, one with LET and, the other with a conventional beads surface structure as a control. Hydroxyapatite (HA) is coated on L.E.T. stem. The dogs were killed three, six, ten weeks later. The harvested femora were cut off seven sections follow by a push out strength test and calculate the rate of bone ingrowth by measuring images of backscattered electron imaging-scanning electron microscopy (BEI-SEM) of each cross section using the NIH Image. Thin-sectioned tissues were then stained with toluidine blue.

Results: The push-out strength of the L.E.T. stems were 146 to 384% greater and its rate of bone ingrowth were 193 to 226% greater than that of the conventional beads stems. HA coated L.E.T. implants had the new bone formation down to the bottom of the porous portion even after three weeks, the findings which was not seen in the conventional beads stems in microscopic and BEI-SEM finding.

Discussion and Conclusion: Space controlled interface (L.E.T.) was proven to keep an adequate pore within the interface and induce true bone ingrowth in the space. Using L.E.T. structure, faster bone ingrowth and stronger fixation of the stem to the bone can be obtained.

We developed LET (Lamellar Etched Titanium) porous structure as a new bone-prosthesis interface, which is made by piling up and fusing the etched titanium thin layers. This method can control pore size and porosity easily and obtain definite interconnective open pore structure (average porosity 65%, average pore size 500 micrometer)

Materials and method: The characteristics of bone ingrowth of LET coated with hydroxyapatite (HA) have been studied in a transcortical rabbit model.

We implanted two types of interface, one with LET and the other with a conventional rough surface structure, which is made with inert gas-shielded arc spraying (ISAS) technique (Ra 40 micrometer) Both materials have coated with HA using the flame spray method. Mechanical and histological studies were performed at 2, 4, 9 and 12 weeks.

Results: Previous scanning electron microscopy study of HA coated LET revealed an even HA layer consecutively distributed from its surface to the bottom without pore obstruction. Mechanical detaching tests showed that the interfacial tensile strength of LET increased with time and were significantly higher than that of ISAS at 4, 9 and 12 weeks (P< 0.05). Histological studies demonstrated that LET had induced deep and wide bone ingrowth into the pore structure. Even at 2 weeks, the immature bone trabeculae were observed stretching to the bottom of LET and, at 9 and 12 weeks, the new bones infiltrated into porous structure changed into maturing osseous tissue. Further, residual new bones of the detached side were observed in and on the pores of LET. It suggested that detaching occurred inside of new bones. In contrast, no residual bone was found onto ISAS implant at 4, 9 and 12 weeks.

Conclusion: The LET structure was proved to have desirable properties for bone ingrowth and, furthermore, the osteoinductivity of HA could enhance its character.