Introduction

Range of motion (ROM) simulation of the hip is useful to understand the maximum impingement free ROM in total hip arthroplasty (THA). In spite of a complex multi-directional movement of the hip in daily life, most of the previous reports have evaluated the ROM only in specific directions such as flexion-extension, abduction-adduction, and internal - external rotation at 0° or 90° of hip flexion. Therefore, we developed ROM simulation software (THA analyzer) to measure impingement free ROM in any positions of the hip. Recent designs of the hip implants give a wider ROM by increasing the head diameter and then, bone to bone impingement can be a ROM limit factor particularly in a combination of deep flexion, adduction and internal rotation of the hip. Therefore, the purpose of this study were to observe an individual variation in the pattern of the bone impingement ROM in normal hip bone models using this software, to classify the bone impingement ROM mapping types and to clarify the factors affecting the bone impingement type.

Summary

Bi-plane Image matching method is very useful technique to evaluate the loaded 3D motion of each cervical level.

Introduction

Cervical orthoses are commonly used to regulate the motion of cervical spines for conservative treatment of injuries and for post-operative immobilization. Previous studies have reported the efficacy of orthoses for 2D flex-extension or 3D motions of the entire cervical spine. However, the ability of cervical orthoses to reduce motion might be different at each intervertebral level and for different types of motion (flexion-extension, rotation, lateral bending). The effectiveness of immobilizing orthoses at each cervical intervertebral level for 3D motions has not been reported. The purpose of this study is to evaluate the effectiveness of the Philadelphia collar to each level of cervical spines with 3D motion analysis under loading condition.

Purpose: To introduce our new surgical technique for better correction of scoliosis and rib hump deformity.

Surgical technique: The technique consists of rib mobilization (RM) and hook rotation maneuver (HRM). RM is to release costo-vertebral connection bilaterally from T5 to T10 to mobilize ribs obtaining more flexibility of the spine. HRM is to rotate convex side hooks on transverse process ventrally pushing down the ribs, thus giving derotational force while compression force is applied.

Subjects: Forty-six idiopathic cases with minimum 1 year follow-up were reviewed. The average F-up period is 15.1m( 12 – 24). The average age at surgery was 20.1 y(12–57). Conventional multiple hooks, screws, wires and rod system was used. Results: The average Cobb angle was 56.0 ( 40 – 93) degrees. The average rib hump was 22.5 mm in height and 13.9 degrees by scoliometer. At 3 w post-op, 6 m post-op, and at F-up, the average Cobb angle was 13.0 (77.9%), 15.6 (73.4%), and 16.0 (72.6%, 43 – 100%)) respectively. The average rib hump at 6m post-op and at F-up was 9.7 mm in height and 6.8 degrees, and 10.3mm and 6.4 degrees respectively. The hump index at thoracic level was 5.49 pre-op, 3.73 at 6m and 4.25 at F-up.

Conclusion: Our new technique improved the correction of not only scoliosis but also thoracic hump significantly. The derotational force by HRM is weaker than direct derotation by pedicle screw. However, it is undoubtedly a safer and less expensive technique than thoracic pedicle screw, providing significant correction of rib hump.

The anterior pelvic plane (APP) through the bilateral anterior superior iliac spines (ASIS) and pubic tuberosities is often used as a pelvic reference in measuring orientation of the acetabular cup in total hip arthroplasty. Apophyses such as ASIS are, however, anatomically variable among patients and APP does not always represent the functional pelvic tilt in the sagittal plane in each patient. Therefore, malposition of the cup and recurrent dislocation may occur even though the cup is placed in a safe zone when measured against APP. We analyzed dynamic pelvic tilt angle in the sagittal plane using a motion analysis system after THA and we found a case of recurrent dislocation due to an unusual APP tilt.

A 77-year-old woman underwent primary THA 3 years ago and cup re-implantation was done with the use of a 10-degree elevated liner and the head diameter was increased from 26mm to 28 mm after two anterior dislocations. However, posterior dislocation occurred 11 times after this. A second revision was performed with a 36 mm head and cup anteversion was optimized against APP. Further posterior dislocations occurred twice again. To probe the cause of recurrent dislocation, we performed motion analysis using a 6-camera VICON system and the markers were registered to the bone and implant models based on the postoperative CT images. This system visually represents four-dimensional dynamic motions that include the time sequential transitions of components and their posture. The cup had been placed in 6 degrees of radiographic anteversion against APP, and in −13 degrees of radiographic retroversion in supine (FPP), because the pelvic flexion angle in supine was 17.6 degrees. Furthermore, when standing, the pelvic flexion angle increased 10 degrees.

Malposition of the acetabular cup in THA is the most common cause of dislocation. To avoid errors in cup placement, computer navigation systems have been introduced and most of the navigation systems refer APP to establish cup orientation. There are two drawbacks in using APP as the reference. One is that apophyses such as ASIS develop variably in each patient with a resulting variability in APP tilt in the sagittal plane in supine. The other is significant changes in pelvis tilt during various activities of daily living such as standing, walking, and sitting. Therefore, even if cup orientation is acceptable when referencing APP, it can be mal-oriented in a functional position of the pelvis as in this case, which showed proper anteversion against APP but retroversion in supine, standing and sitting.

In conclusion, we found that there exists a case in which APP is not a suitable pelvic reference in determining orientation of the cup.

Cervico-thoracic congenital scoliosis is a difficult deformity to obtain good correction due to its anatomical characteristics and lack of proper instrumentation. Surgical treatments often end up with poor correction by convex epiphysiodesis alone, making hideous residual head tilt. This is a report of 2 cases with cervico-thoracic congenital scoliosis, which underwent total excision of hemivertebra, instrumentation and fusion through posterior approach alone.

Case 1. 8y2m old Girl who had T1, T3, T7 hemivertebrae with a left convex curve from C7 to T11. At age 5. she had tilted head and left convex 33 degrees scoliosis. Only regular observation was done. At age 8y2m, the scoliosis had progressed to 49degrees. Total excision of T1 hemivertebra was performed. At age 10y8m, total excision of T7 hemivertebra, extension of instrumentation and fusion to T10 was performed. These procedures brought almost normal alignment on both sagittal and coronal plane. However, lower compensatory curve progressed later on, fusion was extended to L2 at age 13 resulting in excellent balance.

Case 2: Girl. 2y7m. Multi-level hemivertebrae. C6-L1 L100 degrees.

Total excision of T12 hemi, short fusion and instrumentation reduced the scoliosis to 50 degrees. Five months later, total excision of T9 hemi was done. Four months later, concave side instrumentation from T2 to L2 without fusion was done. At age 4y2m, total excision of T1 hemi was done using cervical pedicle screw. The scoliosis is being controlled at 35 degrees with one extension of the rod later on.

While numerous studies have examined dislocation caused by basic everyday movements, no objective studies have investigated body positions to minimize risk of dislocation during intercourse. We therefore used a four-dimensional motion analysis system to assess sexual activities in patients who had undergone total hip arthroplasty (THA), to identify body positions displaying less risk of dislocation.

Five body-surface infrared sensors were placed on five healthy female volunteers, and maximum hip joint angle was measured. Subjects were asked to take the following three body positions: supine (missionary); top (woman on top); and kneeling (doggy-style). Angle data obtained using body surface markers were combined with three-dimensional skeletal models extracted using CT images obtained from the 24 joints of 16 patients who had undergone THA, to ascertain angles at which collision with the artificial joint or skeleton would occur.

Collision angle for: supine position at maximum abduction in flexion was 77±16° in flexion and 82±57° in medial rotation; top position at maximum extension was 36±16° in flexion and 68±53° in medial rotation; top position at maximum flexion was 12±9° in flexion and 14±11° in medial rotation; kneeling position at maximum extension was 115±1° in flexion and 127±44° in medial rotation; and kneeling position at maximum flex-ion was 14±8° in flexion and 17±11° in medial rotation.

The present study only assessed risk for dislocation caused by collision with the artificial joint or skeleton, and did not take into account the effects of soft tissue. However, we were able to quantitatively assess angle of the hip joint for some leg positions involved with various common coital positions. The results showed that the supine position at maximum abduction in flexion is relatively safe, since the range of motion before collision would occur was relatively wide. In addition, top and kneeling positions at maximum extension were relatively safe, but caution must be exercised at maximum flexion, as not much extra angle was available in flexion and medial rotation.

We have developed a novel system of 4-dimensional motion analysis after total hip arthroplasty (THA) that can aid in preventing dislocation by assessing safe range of motion for patients in several daily activities.

This system uses skeletal structure data from CT and motion capture data from an infrared position sensor. A 3-D model reconstructed from CT data is combined with the motion capture data. Using this system, we analyzed hip motion when getting up from and sitting down in a chair or picking up an object while sitting in a chair in 17 patients (26 hips) who underwent THA. To assess the accuracy of this system’s measurements, open MRI was used to evaluate positions of skin markers against bones in 5 healthy volunteers in various postures.

No impingement between bones and/or implants was found in any subjects during any activities. However, mean angle at the point of maximum hip flexion was different for each patient. The open MRI results indicated that average error in hip angle of the present system was within 5 degrees for each static posture.

The functional position of the pelvis during daily activities must be taken into account when assessing the real risk of dislocation. The present system enables dynamic analysis involving not only alignment of components and bones of each patient, but also individual differences in characteristics of daily motions. Further investigation using this system can help determine safe ranges of motion for preventing hip dislocation, improving the accuracy of individualized guidance for patients regarding postoperative activities.

Introduction: One of the important goals of scoliosis surgery is to improve or to prevent deterioration of pulmonary function. There have been many reports on this subject, yet there are a few reports on cases that had surgery by modern multi-hook system. Modern instrumentation can provide better correction; therefore better results on pulmonary function can be expected.

The purpose of this study is to analyse post-operative pulmonary function in cases that underwent Isola instrumentarion to scoliosis.

Method and Results: There are 130 cases (Male 23, Female 107) who underwent Isola instrumentation to scoliosis from December 1991 to December 1998 and had pulmonary function test pre-operatively and at the time of two-years follow-up. Aetiologies were Idiopathic 119, Congenital 3, Neurofibromatosis 2, Marfan 4, and Others 2. Average age is 15 at the time of operation ranging 10 to 26. One hundred and twenty-six cases had single operation and four cases had two-staged anterior-posterior surgery.

VC, %VC, Fev.l.0, % Fev.1.0 were measured pre-operatively and two years post-operatively. Body height correction was done using Kohno’ s equation to obtain % VC.

The pre-operative average VC, %VC, Fev.l.0, and %Fev.l.0 were 2.4l, 84.2%. 2.1l, and 85.5% respectively. They were 2.6l, 83.0%. 2.3l, and 87.2% at 2 years postoperatively. Cases were diagnosed according to the change of % VC using a threshold of 10% change. If the change of the %VC is less than 10%. it is diagnosed as unchanged. Thirty cases (23.1%) had decreased %VC, 70 cases (53.8%) unchanged and 21 cases (16.1%) had increased %VC.

The cases were divided into four groups according to the pre-operative % VC. Group 1; the pre-operative %VC was less than 60%. Group 2; 60% to 69%, Group3; 70% to 79%. and Group 4; 80% or more. The average pre- and post-operative %VC were 50% and 54% in Group 1, 65.5% and 67.5% in Group 2, 75.4% and 80.5% in Group 3, 94.8% and 90.6% in Group 4.

Conclusion: The results showed that a patient can expect to have normal or almost normal VC post-operatively when the pre-operative % VC is larger than 70%. On the other hand, if the pre-operative % VC is less than 60% the chance to have normal or almost normal VC . post-operatively is very little. Therefore, surgery must be done before % VC deteriorates to less than 60%. The goal of scoliosis treatment is three fold; 1) to restore stable, balanced, and stable spine, 2) to have normal pulmonary function, 3) to be emotionally stable. In 61% of the cases the surgical technique applied was conventional method which gave average % correction of 68%. From 1997, a new correction technique using Isola system has been applied. Results at one-year follow-up showed better results. It is my opinion that the treatment of scoliosis should be focused not only to the correction of coronal and sagittal curvature but to the correction of thoracic cage deformity.

We report a femoral shaft fracture that reduced spastic muscle hypertonus of the affected lower limb of a child with cerebral palsy. The child was a five years old boy. He was borne with spastic quadriplegia (total body involvement). He could not sit, stand and walk by himself. The femoral shaft fracture occurred during physiotherapy. The injury itself was iatrogenic although the bones were accompanied by roentgenological bone atrophy. Such bone atrophy comes from disuse or low physical activity.

The fracture was treated by a hip spica cast. The femoral bone was shortened at the time of immobilization. After removing the cast, the spastic muscle hypertonus was apparently reduced. This instructive case suggests osteotomy as a new effective treatment for spastic hypertonus. Osteotomies would make few scars in the muscles and tendons comparing to lengthening of multiple tendons and muscles. In this case, osteotomies are believed to be a non-invasive treatment rather than other available operative procedures.

We studied degenerative changes in the cervical intervertebral discs of 497 asymptomatic subjects by MRI and evaluated disc degeneration by loss of signal intensity, posterior and anterior disc protrusion, narrowing of the disc space and foraminal stenosis. In each subject, five disc levels from C2–C3 to C6–C7 were evaluated.

The frequency of all degenerative findings increased linearly with age. Disc degeneration was the most common observation, being present in 17% of discs of men and 12% of those of women in their twenties, and 86% and 89% of discs of both men and women over 60 years of age. We found significant differences in frequency between genders for posterior disc protrusion and foraminal stenosis. The former, with demonstrable compression of the spinal cord, was observed in 7.6% of subjects, mostly over 50 years of age.

Our results should be taken into account when interpreting the MRI findings in patients with symptomatic disorders of the cervical spine.