Three-dimensional mechanical evaluation of joint contact pressure in 12 periacetabular osteotomy patients with 10-year follow-up

Background and purpose Because of the varying structure of dysplastic hips, the optimal realignment of the joint during periacetabular osteotomy (PAO) may differ between patients. Three-dimensional (3D) mechanical and radiological analysis possibly accounts better for patient-specific morphology, and may improve and automate optimal joint realignment.Patients and methods We evaluated the 10-year outcomes of 12 patients following PAO. We compared 3D mechanical analysis results to both radiological and clinical measurements. A 3D discrete-element analysis algorithm was used to calculate the pre- and postoperative contact pressure profile within the hip. Radiological angles describing the coverage of the joint were measured using a computerized approach at actual and theoretical orientations of the acetabular cup. Quantitative results were compared using postoperative clinical evaluation scores (Harris score), and patient-completed outcome surveys (q-score) done at 2 and 10 years.Results The 3D mechanical analysis indicated that peak joint contact pressure was reduced by an average factor of 1.7 subsequent to PAO. Lateral coverage of the femoral head increased in all patients; however, it did not proportionally reduce the maximum contact pressure and, in 1 case, the pressure increased. This patient had the lowest 10-year q-score (70 out of 100) of the cohort. Another hip was converted to hip arthroplasty after 3 years because of increasing osteoarthritis.Interpretation The 3D analysis showed that a reduction in contact pressure was theoretically possible for all patients in this cohort, but this could not be achieved in every case during surgery. While intraoperative factors may affect the actual surgical outcome, the results show that 3D contact pressure analysis is consistent with traditional PAO planning techniques (more so than 2D analysis) and may be a valuable addition to preoperative planning and intraoperative assessment of joint realignment.     

Periacetabular osteotomy through a modified ollier transtrochanteric approach for treatment of painful dysplastic hips

BACKGROUND: Elimination of abnormally high joint-loading resulting in excessive contact stresses may prevent or reduce the onset of osteoarthrosis in a dysplastic hip. A number of periacetabular osteotomies have been shown to be effective in restoring normal hip-joint mechanics. We treat acetabular dysplasia with a periacetabular osteotomy performed through a modified Ollier transtrochanteric approach. In this report, we describe the operative technique and the clinical and radiographic results. METHODS: Thirty-six patients (thirty-eight hips) in whom a painful dysplastic hip had been treated with a periacetabular osteotomy between March 1991 and June 1999 were included in the study. There were thirty-five female patients and one male patient with a mean age (and standard deviation) at the operation of 29.42 +/- 9.1 years. The technique utilizes a u-shaped skin incision, and a routine osteotomy of the greater trochanter with distal transfer if needed, and allows excellent visualization enabling the surgeon to perform the periacetabular osteotomy without penetrating the joint. RESULTS: At a mean of five years and six months postoperatively, the mean modified Harris hip score had improved from 59.1 +/- 15.8 points preoperatively to 87.97 +/- 14.3 points. Radiographically, the degree of osteoarthrosis had decreased in eleven hips, remained unchanged in twenty-four, and worsened in three. The mean anterior center-edge angle had increased from 22.0 degrees +/- 12.9 degrees to 36.1 degrees +/- 12.3 degrees, the mean lateral center-edge angle had increased from -2.7 degrees +/- 14.4 degrees to 26.6 degrees +/- 14.1 degrees, the mean acetabular index angle had improved from 23.4 degrees +/- 6.6 degrees to 12.7 degrees +/- 4.6 degrees, and the mean acetabular head index had increased from 48.2% +/- 12.7% to 73.1% +/- 16.0%. The Shenton line was restored in eleven hips. Thirty patients (thirty-two hips; 84%) had a satisfactory result. A poor preoperative functional score was associated with an unsatisfactory outcome (p = 0.00191). Complications included prolonged limping (eleven hips); numbness in the distribution of the lateral femoral cutaneous nerve (four); osteonecrosis of the rotated acetabular fragment (two); and acetabulofemoral impingement, heterotopic ossification, and a defect on the rotated ilium (one hip each). CONCLUSIONS: Painful dysplastic hips should be treated before function becomes seriously impaired. We believe that periacetabular osteotomy through a modified Ollier approach, which allows osseous cuts to be made under direct vision, can be learned readily. It provides improved femoral head coverage and relief of symptoms in most painful dysplastic hips in adolescents and young adults.     

Computer-assisted navigated cup placement in primary and secondary dysplastic hips

AIM: The positioning of an acetabular implant has great influence on the range of motion as well as the charger of dislocation of total hip arthroplasty. Using modern CAS systems the reproduction of the cup position after three-dimensional planning based on computed tomography is possible. We investigated the reliability of the position of the acetabular implant in primary and secondary dysplastic cases. METHOD: Within a prospective randomised study in a total of 100 hip replacements with postoperatively controlled cup position using a computed tomography, we reinvestigated especially the 18 dysplastic and two secondary dysplastic cases. RESULTS: In the dysplastic cases we could realise nearly the same anteversion angles (22.4 degrees to 21.5 degrees) with a bigger standard deviation (+/- 7.68 degrees to +/- 7.29) than in the normal collective. Even the inclination angles (44.5 degrees +/- 5.47 degrees) could be realized nearly the same as in the normal cases (42.3 degrees +/- 4.31 degrees). The depth of the cup implantation could be realised in 15 of 18 cases. CONCLUSION: The CAS system is helpful even in dysplastic cases. The advantage of three-dimensional preoperative CT-based planning is apparent. The surgeon is not able to plan and realise the ideal cup position in some individual.     

Effects of rotation on measurement of lower limb alignment for knee osteotomy.

The purposes of this study were to clarify the effects of rotation on two-dimensional measurement of lower limb alignment for knee osteotomy using a three-dimensional method and to determine whether this 3-D simulation method could help with planning of knee osteotomy. We developed computer software to calculate femorotibial angle (FTA) and hip-knee-ankle angle (HKA) and simulate knee osteotomy from a CT-based 3-D bone model of the lower limb. Lower limb rotation on anteroposterior long-standing radiographs was measured by superimposing the 3-D bone models. Changes in alignment with limb rotation were calculated using the software. FTA after virtual closed-wedged osteotomy was measured for a hypothetical case of a rotation error of the osteotomy plane in reattaching the proximal cutting surface to the distal cutting surface. For 31 varus knees in 20 patients with medial compartment arthritis, the mean rotation angle, relative to the epicondylar axis, with variable limb position was 7.4 +/- 3.9 degrees of internal rotation (mean +/- SD), ranging from 8 degrees of external rotation to 14 degrees of internal rotation; the mean changes in FTA and HKA were 3.5 +/- 2.2 degrees (range, 0.4-8.6) and 1.6 +/- 1.3 degrees (range, 0.2-4.9), respectively. The FTA "flexion angle" (lateral view alignment from neutral AP) and the absolute HKA "flexion angle" correlated with the change in FTA and HKA with limb rotation, respectively (FTA, R = 0.999; HKA, R = 0.993). The mean change in FTA after virtual closed-wedged osteotomy was 3.2 degrees for internal and external 10 degrees rotation errors in reattaching the osteotomy plane. Rotation may affect measurement of lower limb alignment for knee osteotomy, and 3-D methods are preferable for surgical planning.     

Design and development of a computer assisted glenoid implantation technique for shoulder replacement surgery.

OBJECTIVE: Replacement of the diseased shoulder joint with implants is a procedure whose frequency is rapidly increasing. However, glenoid replacement remains challenging due to the difficult joint exposure and visualization of anatomical reference landmarks during the procedure. Improper positioning of the glenoid component can lead to early failure. The objective of this study was to develop and evaluate a Computer Assisted Glenoid Implantation (CAGI) technique to achieve a more accurate and reliable placement of the glenoid component. MATERIALS AND METHODS: Twenty cadaveric scapulae were imaged with CT. The accuracy of an electromagnetic tracking system and 3D surface modeling for the measurement of glenoid position was compared to that of the standard CT-based method. Custom jigs were then developed to track instruments and to correct for scapular motion during in vitro trials. A standardized protocol for determining, in real time, the glenoid position and placement was developed and validated. RESULTS: The version angles measured by the tracking system, CT, and the 3D modeling software were 0.0 +/- 1.2 degrees , -1.3 +/- 1.0 degrees , and -1.1 +/- 1.1 degrees , respectively. The magnitudes for inclination angles were 0.7 +/- 0.7 degrees , 0.9 +/- 0.8 degrees , and 1.0 +/- 0.7 degrees , respectively. A statistically significant difference was found only between measurements made with the tracking system and with CT (p < 0.05). Testing of the CAGI system in a cadaveric trial resulted in an accuracy of 1.17 degrees of version and 0.60 degrees of inclination. The procedure was readily performed with excellent feedback and guidance for the surgeon. CONCLUSIONS: Preoperative planning using CT imaging with 3D modeling and intraoperative tracking were combined to produce improved accuracy and reliability of glenoid implantation in the setting of total shoulder arthroplasty.     

Changes in load-bearing area after Ganz periacetabular osteotomy evaluated by multislice CT scanning and stereology

BACKGROUND: We used a stereologic method based on 3D CT scanning to estimate the projected load-bearing surface in the hip joint. PATIENTS AND METHODS: 6 normal hip joints and 6 dysplastic hips were examined. The latter were CT-scanned before and after periacetabular osteotomy. RESULTS: We found that the average area of the projected load-bearing surface of the femoral head preoperatively was 7.4 (6.5-8.4) cm2 and postoperatively 11 (9.8-14) cm2, which was similar to the load-bearing surface in the normal control group. We performed double measurements and the coefficient of error of the mean was estimated at 1.6%. Due to overprojection, an overestimation of about 3.8% on the projected load-bearing surface occurred. Consequently, the stereologic method proved to be precise and unbiased. INTERPRETATION: Our findings indicate that this method is of value for monitoring the load-bearing area in the hip joint of patients undergoing periacetabular osteotomy.     

Radiographic angles in hallux valgus: differences between measurements made manually and with a computerized program

BACKGROUND: The objective of this study was to compare angular measurements in the evaluation of hallux valgus deformities using a goniometer and a computerized program to assess degree of concordance between the two methods and determine the reliability of manual measurements. METHODS: Angles measured included the hallux valgus angle (HVA), the intermetatarsal angle (IMA), the distal metatarsal articular angle (DMAA), and the proximal phalangeal articular angle (PPAA), also called the hallux valgus interphalangeus angle or interphalangeal angle. Measurements were made on preoperative weightbearing radiographs in 176 patients with symptomatic hallux valgus. Manual measurements were made with a goniometer by an orthopaedic surgeon. An independent experienced technician used digitized images to perform angular measurements with the Autocad software program (Autodesk Inc., San Rafael, CA). RESULTS: HVA values obtained with the two techniques were similar. However, significantly higher mean values were obtained with the Autocad for the IMA and PPAA measurements, and higher mean values were obtained for the DMAA measurement with the manual technique. Whereas differences were more or less randomly distributed for the HVA, in the remaining patients, measurements were clearly related to the measurement technique, i.e., for the DMAA, the manual technique had a tendency to show higher values, and for the IMA and PPAA the manual technique showed lower values than the computer. Correlations between both techniques for the different angular measurements were as follows: HVA, -0.179 (p = 0.018); DMMA, -0.294 (p < 0.001); PPAA, -0.876 (p < 0.001); and IMA, -0.661 (p < 0.001). The intraclass correlation coefficient (ICC) showed that the concordance between manual and Autocad angular measurements was excellent for the HVA (ICC = 0.89) and DMAA (ICC = 0.80) and very poor for the PPAA (ICC = 0.11) and IMA (ICC = 0.42). CONCLUSIONS: Angular measurements made on weightbearing radiographs with the Autocad in patients with hallux valgus deformities were more reliable than those made with a goniometer. Although for large angles, such as HVA and DMAA, results obtained with both measurement techniques were similar. Manual measurements, however, may underestimate the true values of the smaller IMA and PPAA angles.     

Birth after peri-acetabular osteotomy

We evaluated the radiological pelvic diameter after the bernese periacetabular osteotomy (PAO) and its influence on the modality of birth. Out of 93 woman, 17 had a total of 28 babies after PAO; 18 children were delivered spontaneously and 10 by caesarean section. The rate of section (36 %) was twice as high after PAO as in a normal population. In 50 % the indication to perform a section was made because the obstetrician anticipated problems during delivering after PAO. The average weight of birth was 3348 g +/- 285 g in the spontaneous delivery group, 3475 g +/- 356 g in the section group. The weight of birth didn't correlate neither with the duration of delivery nor with the indication to perform a section. The 17 woman who had a baby after PAO didn't show a significant change of the radiological diameters of the pelvis: pelvic entrance (before PAO 15. 4 cm, after PAO 15.7 cm), mid-pelvis (before PAO 11.8 cm, after PAO 11.8 cm) and pelvic outlet (before PAO 14.2 cm, after PAO 13.7 cm). We found that the PAO does not influence the anatomical diameters of the birth canal and therefore is not an indication for a section.     

Periacetabular osteotomy. Good pain relief in symptomatic hip dysplasia, 32 patients followed for 4 years

BACKGROUND: When surgical treatment of dysplastic hip osteoarthrosis is necessary, osteotomy is preferable to fusion or THR. We evaluated periacetabular osteotomy as a method of choice. PATIENTS AND METHODS: We treated 36 symptomatic dysplastic hip joints (32 patients) with the Bernese periacetabular osteotomy (PAO) between 1994 and 2001. We used the ilio-inguinal (I-I) approach in 32 hips and a modified Smith-Petersen (S-P) approach in 4. The patients were followed for mean 4 (1.5-8) years. In 1 patient with coxa valga, a varus femoral osteotomy was performed 1 year after PAO. 2 hips, in which we used the modified S-P approach, necessitated a capsulotomy. RESULTS: The median Merle d'Aubignè score increased from 13 points preoperatively to 16 points postoperatively. This improvement in terms of pain, motion and ambulation was accompanied by spatial reorientation and correction. The lateral center edge angle of Wiberg (CE) improved from an average of 7 degrees to 28 degrees. The anterior center edge angle of Lequesne (FP) improved from an average of 18 degrees to 28 degrees. The acetabular index angle (AC) improved from an average of 22 degrees to 10 degrees. Major complications included 1 partial lesion of the sciatic nerve, 1 malunion and 1 combined nonunion of the pubic and ischiatic osteotomy. 2 patients underwent subsequent total hip replacement (THR) for progressive osteoarthrosis with pain. INTERPRETATION: We found good radiographic correction of deformities, improvement of hip function and pain relief with an acceptable complication rate. With appropriate patient selection, this procedure is the most physiological treatment of symptomatic hip dysplasia in young adults. In addition to relieving symptoms, it may prevent and postpone the development of secondary osteoarthrosis.     

Quantitative evaluation of angular measurements on plain radiographs in patients with slipped capital femoral epiphysis: a 3-dimensional analysis of computed tomography-based computer models of 46 femora

BACKGROUND: In cases of slipped capital femoral epiphyses (SCFE) findings on plain radiographs help to determine the further necessary course of action. In severe cases possible surgical procedures are commonly indicated and planned using angular measurements on plain radiographs to describe the extent and direction of the slip. The aim of this study was to quantify the amount of angular errors deriving from this method. METHODS: Data and imaging of 23 consecutive patients with SCFE (31 affected and 15 unaffected femora) were included in this study. We determined shaft-neck/shaft-physis angles on antero-posterior and torsional angles on lateral radiographs in a clinical setting. As a reference we enabled similar angular measurements on CT-based three-dimensional computer models of the same femora bearing no projectional errors and malpositioning problems. RESULTS: In average, shaft-neck- and shaft-physis-angles were overestimated (6.5 degrees and 10.1 degrees ) on plain radiographs and neck torsion underestimated (-15.7 degrees ). In general the variability was high, especially for neck and physeal torsional measurements with standard deviations of +/-11.8 degrees and +/-16.7 degrees . Three out of four torsional measurements on affected femora were outside a +/-10 degrees window of error, about every third outside a +/-20 degrees window. CONCLUSION: Our results suggest to be careful when using plain radiographs as a source to determine the slippage extent in SCFE. Before using a plain radiograph to reject or indicate and plan a correction osteotomy in an individual case of SCFE the surgeon should reassure that radiographic method and patient positioning provide a reproducible and accurate depiction of the femoral geometry. LEVEL OF EVIDENCE: Level II; 23 consecutive patients with SCFE in the senior authors practice; evaluation of the reliability of angular measurements on plain radiographs; CT based 3D computer models of the same femora as a reference.     

Accuracy of length and angle measurements in the roentgen image and sonogram of the pediatric hip joint

The results of measurement of length and angles in the x-ray and ultrasound image of the infantile hip joint are dependent on the different shape of the joint but also on different x-ray projections, on a limited accuracy and incorrect technique in measurement. From our investigations on the accuracy of measurement a differentiation between normal and pathological infantile hip joints is not possible by measuring geometrical data in the x-ray resp. ultrasound image. In the x-ray the greatest possible error of the acetabular angle is +/- 3 degrees, that of the so-called "AMC-angle" +/- 5 degrees and of the Alpha- and Beta-angle in the ultrasound image +/- 10 degrees. Thus the collection of geometrical data in the x-ray and ultrasound image of the infantile hip joint is not more reliable than a qualitative assessment orientated on the osseous resp. cartilaginous corner of the acetabulum.     

Addition-subtraction osteotomy with ligamentoplasty for symptomatic trapezial dysplasia with metacarpal instability

Trapeziometacarpal instability with trapezial dysplasia is a disabling condition long before the radiological changes of osteoarthritis appear. In dysplastic joints surgical soft tissue correction fails to prevent the instability, requiring a correction of the bony anatomy. We combined two techniques described in the past, an abduction osteotomy of the first metacarpal and an opening wedge osteotomy of the trapezium, to which we added a ligament reconstruction. The combination of both osteotomy techniques restores the anatomy and centres the forces acting across the joint. We have done this procedure 21 times since 2003 in 18 patients. Seventeen thumbs were reviewed prospectively with a mean follow-up of 39 (range 16-65) months. Mean QuickDASH improved by 33.9 points, the key pinch improved by 1.8?kg and the grip strength improved by 8.7?kg. The visual analogue scale for pain improved from 7.9 preoperatively to 2 postoperatively. This technique preserves the trapeziometacarpal joint, allowing other techniques to be used if painful arthritis should develop in the middle to long term.     

Segmental lumbar lordosis: manual versus computer-assisted measurement using seven different techniques

OBJECTIVES: Obliteration of end-plate landmarks by interbody fusion has made the traditional measurement of segmental lumbar lordosis nearly impossible. Because the L4-L5 and L5-S1 levels are most likely to be subjected to fusion procedures or arthroplasty and contribute to more than half of normal lumbar lordosis, it is crucial to identify a reproducible and accurate means of measuring segmental lordosis at these levels. METHODS: Twelve spinal surgeons measured lordosis at L4-L5 and L5-S1 on 10 separate radiographs using three techniques for L4-L5 and four techniques for L5-S1. With use of identical radiographs, measurements first were made using a manual method and then were repeated with a computer-assisted method. Measurements were analyzed for both intraobserver and interobserver error. RESULTS: The individual data demonstrated an intraobserver variance of 9.56 and a standard deviation of 3.092 for computerized measurements compared with 7.742 and 2.782 for manual measurements. The interobserver variance was 4.107 with a standard deviation of 2.027 for the computerized group compared with 4.221 and 2.055 for manual measurements. When analyzed as a group to evaluate interobserver error, the pooled data yielded variance of 19.235 for the computerized group and 19.117 for the manual measurements. CONCLUSIONS: Variance calculations identified the Cobb technique and the posterior vertebral body technique as the least variable measurement techniques for the L4-L5 and L5-S1 levels, respectively; however, there was no statistical significance. In direct comparison, the manual and computer-assisted techniques were found to be statistically equivalent with similar degrees of variance. We believe that the anterior vertebral technique, which did not demonstrate a significant difference from other techniques, will prove to be the most reliable method of assessing segmental lumbar lordosis in patients before surgery, after interbody fusion, and after motion-sparing disc arthroplasty.     

Comparison between manual and computer-assisted measurements of hallux valgus parameters

BACKGROUND: The aim of this study was to determine if there are intraobserver and interobserver differences in reliability when measuring hallux valgus angles (HVA), 1-2 intermetatarsal angles (IMA), and distal metatarsal articular angles (DMAA) manually compared to computer-assisted means. Our hypothesis was that the measurements taken by computer-assisted methods of these three forefoot angles would be superior in consistency and accuracy compared to manual measurements. METHODS: Four examiners studied 20 weightbearing anteroposterior radiographs of patients with hallux valgus. Manual measurements were taken on photographic prints using a goniometer and a fine point pen. Computer-assisted measurements were taken on digitized images using computer software. Three sets of measurements by both of these methods were taken 1 week apart. RESULTS: There was no statistically significant difference between digital and manual measurements for any of the three angles measured (p .05). However, the reliability of measurements within a range of 5 degrees for both methods was 70.6% for HVA, 84% for 1-2 IMA, and 59% for DMAA. CONCLUSION: There were no significant differences in interobserver and intraobserver reliability in measuring 1-2 IMA and HVA, regardless of the method of measurement; however, there was a significant difference in interobserver reliability when measuring the DMAA either on computer or manually (p = <.05).     

Effect of increasing distal medial closing wedge metatarsal osteotomies on the distal metatarsal articular angle

The recognition, definition, and management of the congruent hallux valgus deformity continue to evolve. To correct the skeletal deformity and maintain joint congruity, many authors have emphasized the importance of extra-articular procedures. One such procedure is a distal medial closing wedge osteotomy of the first metatarsal. Unfortunately, there are few guidelines to help determine the pre- and intraoperative size of the medial wedge to obtain the desired correction of the distal metatarsal articular angle (DMAA). The purpose of this study was to quantify the effects of increasing distal medial closing wedge osteotomies on the DMAA in an in vitro cadaver model. In this study, a closing wedge osteotomy was performed 2 cm proximal to the articular surface, removing wedges measuring 2 mm, 4 mm, and 6 mm in width. The mean preoperative DMAA was 8.5 degrees, and the mean postoperative DMAAs after 2-mm, 4-mm, and 6-mm closing wedge osteotomies were -2.6 degrees, -10.2 degrees, and -20.2 degrees, respectively. The data showed that for every 1 mm of closing wedge osteotomy, the DMAA decreased by 4.7 degrees +/- 0.6 degrees. These results can be used for pre- and intraoperative planning when surgically correcting a congruent hallux valgus deformity with a distal medial closing wedge osteotomy of the first metatarsal. Additional information obtained from this cadaver study includes (1) increased shortening of the first metatarsal and (2) incongruity produced at the joint after the medial-based osteotomy. The amount of shortening of the first metatarsal correlated directly with the size of the medial-based wedge. The second point indicates that a lateral soft-tissue release may still be required when using this method of reorienting the DMAA.     

Trapezial tilt: a radiographic correlation with advanced trapeziometacarpal joint arthritis

Trapeziometacarpal (TMC) joint arthritis is a common and debilitating condition of the hand. We defined a radiographic measure of trapezial inclination (trapezial tilt) and found a positive correlation between an increased trapezial tilt and severity of TMC joint arthritis. Radiographs (Robert's views) were obtained from 50 pairs of normal hands to evaluate the trapezial tilt to assess radial inclination of the trapezium with respect to the second metacarpal. The trapezial tilt was also measured in 65 hands from 43 patients with various stages of TMC joint arthritis and compared with the normal value. The trapezial tilt for hands without arthritis was 42 degrees +/- 4 degrees, Eaton stages I and II was 42 degrees +/- 4 degrees, and Eaton stages III and IV was 50 degrees +/- 4 degrees. Trapezial tilt angles from the Eaton III and IV group were significantly greater than those of the normal and Eaton I and II groups. Advanced TMC joint arthritis (Eaton III and IV) is associated with an increased trapezial tilt. Mild TMC joint arthritis with an increased trapezial tilt may be treated surgically. We speculate that a trapezio-trapezoid and trapezio-II metacarpal arthrodesis, or an opening wedge osteotomy of the trapezium might arrest the progression of TMC joint arthritis by resetting the slope of the trapezium and decreasing the shear stress within the TMC joint.     

The angle-measuring device, a practical resource in high tibial osteotomy

Thirty-two patients with medial gonarthrosis were subjected to high tibial osteotomy. In 16 knees the base of the osteotomy wedge was measured in mm using a caliper and in another 16 knees the angle-measuring device was used. The miscorrection in correlation to the aimed angle was in the first case 0.2 +/- 4.7 degrees, and in the second case 2.4 +/- 4.1 degrees varus undercorrection. The possible sources of error according to measurement of mechanical axis deviation angle of the knee, angle-measuring device and wedge measuring technique during surgery as well as laxity of knee and age-correlated need of overcorrection are pointed out. The angle-measuring device is an important tool especially in high tibial osteotomy of the knee.     

Addition-subtraction osteotomy combined with ligamentoplasty for symptomatic trapezial dysplasia with instability

INTRODUCTION: Trapezometacarpal instability with trapezial dysplasia is an incapacitating condition long before radiological changes appear. Most of the patients are young and demanding.Treatment is often conservative. Surgical treatment options are relatively classic, starting with a ligamentoplasty of the base of the first metacarpal or a tenotomy of the transarticular accessory slip of the abductor pollicis longus. Other options such as arthrodesis and arthroplasty have not been so successful in this situation. METHOD: The idea arose to combine two techniques described previously. In 1973 Wilson published his technique of abduction osteotomy of the first metacarpal as a treatment for basal osteoarthritis of the thumb. In 2002, Kapandji and Heim published their opening wedge osteotomy of the trapezium in order to correct the slope of a dysplastic trapezium. The combination of both of these techniques avoids closing of the first web by utilising the abduction osteotomy of the first metacarpal. Moreover, the opening wedge osteotomy corrects the dysplastic lateral rim of the trapezium by correcting its slope. RESULTS: We have been performing this technique since 2001 and 2005 in six patients. The preliminary results are encouraging, 5 of them were able to resume their work. A fair result was achieved in a young patient. DISCUSSION: The described technique is relatively easy and has the advantage of preserving the trapezometacarpal joint. In addition, it leaves the door open for other techniques if it eventually should fail in the long term.     

Reliability of lower limb frontal plane alignment measurements using plain radiographs and digitized images

This study evaluated the reliability of lower limb frontal plane alignment measures obtained from plain radiographs measured manually and digitized images measured using a custom computer software package (TheHTO Pro; Fowler Kennedy Sport Medicine Clinic, London, Ontario, Canada). Radiographic measurements used in the planning of high tibial osteotomy, including the mechanical axis angle and mechanical axis deviation, were measured on 42 hip-to-ankle radiographs on two separate occasions by two different raters (A.V.S., J.J.D.). Intraclass correlation coefficients (0.96-0.99) indicated excellent agreement between the manual and computer measurements, suggesting both methods can be used interchangeably. Although test-retest and inter-rater reliability tended to be slightly better when using TheHTO Pro, intraclass correlation coefficients were excellent for both methods (0.97-0.99). The standard errors of measurement were <1 degree for mechanical axis angle and <2 mm for mechanical axis deviation, regardless of method or rater. Based on the observed standard errors of measurement, conservative estimates for the error associated with an individual's mechanical axis angle at one point is approximately 1.5 degrees, and the minimal detectable change on reassessment is approximately 2 degrees. The error associated with an individual's mechanical axis deviation at one point is approximately 4 mm, and the minimal detectable change on reassessment is approximately 6 mm. These results suggest that manual and computer measurements of lower limb frontal plane alignment can be calculated with minimal measurement error. However, the small errors associated with both methods should be considered when making clinical decisions.     

Pelvic remodelling after the Chiari osteotomy. A long-term review

Survivorship analysis of 215 medial displacement pelvic osteotomies undertaken for symptomatic, incongruent dysplasia of the hip since 1966 showed that four of every five hips had not required conversion to a total hip arthroplasty. The radiological characteristics of 86 osteotomies were evaluated at a mean of 18 years (5 to 30) after surgery which was performed at the age of 15.9 +/- 9.5 years. Revision was significantly (p < 0.05) more likely in those patients operated on after the age of 25 years. The centre-edge (CE) angle increased from 2.5 +/- 13.9 degrees before to 41.8 +/- 15.0 degrees immediately after operation. The increase in CE angle was maintained at later review (38.5 +/- 16.5 degrees). Even with severe dysplasia with a CE angle less than zero a substantial improvement in the cover of the femoral head was achieved, usually by medial shift of the lower pelvic fragment. However, the head was not invariably medialised by the osteotomy and lateral movement of the ilium was noted when the position of the joint was relatively medial before operation or when the hip was arthritic. In the longer term pelvic remodelling did not reverse the medialisation produced by the osteotomy, and the cover of the femoral head was maintained.