Distal transfer of the greater trochanter in cox vara

A long-term follow-up study of the clinical and radiographic outcome of distal trochanteric transfer in Legg-Calvé-Perthes' disease following varus derotational osteotomy

AIMS

To assess the long-term effect of distal trochanteric transfer (DTT) on the clinical and radiographic outcomes of patients with Legg-Calvé-Perthes' disease (LCPD) following a varus derotational osteotomy (VDRO).

PATIENTS AND METHODS

For this single centre cross-sectional retrospective study we analysed the data of 22 patients (24 hips) with LCPD who had greater trochanteric overgrowth (GTO), following a VDRO performed in our institution between 1959 and 1983. GTO was defined as an articular trochanteric distance (ATD) of < 5 mm. We compared the radiographic and clinical outcomes of patients who underwent DTT for GTO (ten patients, ten hips) with those who did not (12 patients, 14 hips). Age at presentation was 6.9 years (4 to 10) and 8.0 years (3.2 to 12) respectively. Symptoms associated with the hip and general quality of life were assessed using the Harris hip score (HHS) and the Short Form (SF)-36 questionnaires.

RESULTS

At long-term follow-up of the DTT group, the ATD was 21.7 mm (standard deviation (sd) 9.8) and the centro-trochanteric distance (CTD) was 13.8 mm (sd 8.3). In the control group the ATD was -0.6 mm (sd 7.8) and the CTD was 32.5 mm (sd 10.2). These differences were statistically significant (p < 0.001). The mean HHS and SF-36 scores were 68.4 (sd 25.0) and 62.0 (sd 27.7) for the DTT group and 73.2 (sd 24.2) and 73.3 (sd 21.5) for the control group, respectively. There was no statistically significant difference in the HHS (p = 0.63) or SF-36 score (p = 0.25). There were four patients who had undergone hip arthroplasty in the DTT group (40%) and one patient (7.1%) in the control group (p = 0.07). The mean age at the time of arthroplasty was 45.3 years (42.1 to 56.5) and 43.6 years respectively. Six patients in the DTT group suffered from moderate to severe osteoarthritis (Tönnis grade 2 or 3) compared with eight patients in the control group (60% versus 57.1%, p = 0.61).

CONCLUSION

Although DTT improved the radiographic results in the long-term follow-up of patients with GTO following VDRO, there was no clinical benefit seen in the HHS, SF-36 or incidence of osteoarthritis compared with patients who had not undergone DTT. Cite this article: Bone Joint J 2017;99-B:987-92.

Double intertrochanteric osteotomy for trochanteric overgrowth and a short femoral neck in adolescents

PURPOSE

To review the outcome of Wagner double intertrochanteric osteotomy for trochanteric overgrowth and a short femoral neck in 7 adolescents.

METHODS

Records of one male and 6 females aged 15 to 20 years who underwent modified Wagner osteotomy for trochanteric overgrowth and a short femoral neck by a single senior surgeon were reviewed. The diagnoses were coxa vara (n=2), developmental dysplasia of the hip (n=3), Leg-Calve-Perthes (n=1), and proximal femoral focal deficiency (n=1). Radiological indication for double intertrochanteric osteotomy included a neck-shaft angle (NSA) <120º or a centre trochanter distance (CTD) <28 mm. Function was evaluated using the Children's Hospıtal Oakland Hip Evaluation Scale (CHOHES). The articulotrochanteric distance (ATD), CTD, NSA, and the distance between the centre of the femoral head and the centre of the acetabulum (MZ) were measured on radiographs.

RESULTS

The mean follow-up duration was 61 (range, 28-86) months. The ATD improved from 16±11.5 mm to -6.3±10.2 mm (p=0.018), the CTD from 27.9±3.5 mm to 36.4±7.1 mm (p=0.018), the NSA from 112º±24.4º to 131º±16º (p=0.028), the MZ from 12.7±6.5 mm to 7.7±4.2 mm (p=0.028), and the CHOHES score from 62.1±8.7 to 84±9.6 (p=0.017). One patient had delayed union. Two patients had persistent Trendelenburg gait. Two patients declined second-stage surgery for acetabular dysplasia after solving the femoral side problems at the first stage. One of them developed hip arthrosis.

CONCLUSION

Double intertrochanteric osteotomy is a viable treatment option for adolescents with trochanteric overgrowth and a short femoral neck.

Osteotomy of the greater trochanter: effect on gluteus medius function

PURPOSE

Advancement of the greater trochanter alters the function of the gluteus medius muscle. However, with the exception of clinical studies and biomechanical lever arm studies, no publications that analyze the consequences of advancement of the greater trochanter on the muscle function exist. The aim of the study was to analyze the mechanical changes of gluteus medius after osteotomy of the greater trochanter in a lab setting.

METHODS

An anatomical study of origin and insertion of the gluteus medius was carried out on four hips. Based on the dissections, a string model was developed dividing the muscle into five sectors. Changes in muscle fiber length were measured for every 10° of flexion, internal and external rotation and abduction with the trochanter in anatomic, proximalized and distalized positions.

RESULTS

Distalization of the trochanter leads to an imbalance of muscle action, moving the isometric sector of the muscle anteriorly with more muscle sectors being active during flexion and less during extension. Stretching of the muscle increases passive forces but decreases the force generation capacity of the muscle and at the same time increased muscle fiber excursion may require more energy consumption, which may explain earlier fatigue of the abductor musculature after distalization of the trochanter. For abduction, distalization of the muscle attachment leads to a change in contraction pattern from isometric to isotonic. Optimal balancing and excursion of the muscle is when the tip of the greater trochanter is at level with the hip rotation center.

CONCLUSIONS

In hips with high riding trochanter, the optimal position is at the level of the center of hip rotation. Excessive distalization should be avoided. As the conclusions and considerations are based on a lab setting, transfer to clinical practice may not necessarily apply.

The role of femoral neck anteversion in the development of osteoarthritis in dysplastic hips

There have been several studies examining the association between the morphological characteristics seen in acetabular dysplasia and the incidence of the osteoarthritis (OA). However, most studies focus mainly on acetabular morphological analysis, and few studies have scrutinised the effect of femoral morphology. In this study we enrolled 36 patients with bilateral acetabular dysplasia and early or mid-stage OA in one hip and no OA in the contralateral hip. CT scans were performed from the iliac crest to 2 cm inferior to the tibial tuberosity, and the morphological characteristics of both acetabulum and femur were studied. In addition, 200 hips in 100 healthy volunteer Chinese adults formed a control group. The results showed that the dysplastic group with OA had a significantly larger femoral neck anteversion and a significantly shorter abductor lever arm than both the dysplastic group without OA and the controls. Femoral neck anteversion had a significant negative correlation with the length of the abductor lever arm and we conclude that it may contribute to the development of OA in dysplastic hips.

Does trochanteric transfer eliminate the Trendelenburg sign in adults?

BACKGROUND

Premature closure of the proximal femoral growth plate results in coxa brevis, which usually is associated with insufficiency of the hip abductors. Distal and lateral transfer of the greater trochanter sometimes is recommended to correct this problem. Most of what is known arises from studies of children and adolescents.

QUESTIONS/PURPOSES

We asked whether this procedure in adults with coxa brevis would eliminate hip abductor insufficiency and would improve their hip function based on the Harris hip score (HHS).

PATIENTS AND METHODS

We prospectively followed 11 patients, aged 19 to 55 years (mean, 40 years) who had distal and lateral trochanteric transfer. All patients had pain and a positive Trendelenburg test before surgery. This test was performed at the latest followup by three observers and the interobserver reliability was determined by the kappa coefficient. The HHS was obtained before surgery and at the latest followup. The minimum followup was 25 months (mean, 52 months; range, 25-77 months).

RESULTS

Insufficiency of the hip abductors was eliminated in seven (according to two observers) and eight (according to one observer) of the 11 patients after surgery; the kappa coefficient ranged from 0.79 to 1.0. The mean HHS improved from 64 points preoperatively to 76 points at the final followup. The two patients with preexisting severe osteoarthritis of the hip had the worst final scores and persisted with a positive Trendelenburg test at the final followup.

CONCLUSIONS

Distal and lateral transfer of the greater trochanter can eliminate insufficiency of the hip abductors and improve joint function in adult patients with coxa brevis and we believe should be considered for patients without severe osteoarthritis of the hip.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Biomechanical optimization of different fixation modes for a proximal femoral L-osteotomy

BACKGROUND

Numerous proposed surgical techniques have had minimal success in managing greater trochanter overgrowth secondary to retarded growth of the femoral capital epiphysis. For reconstruction of residual hip deformities, a novel type of proximal femur L-osteotomy was performed with satisfactory results. Although the clinical outcome was good, the biomechanical characteristics of the femur after such an osteotomy have not been clearly elucidated. Therefore, this study presents a three dimensional finite element analysis designed to understand the mechanical characteristics of the femur after the L-osteotomy.

METHODS

A patient with left hip dysplasia was recruited as the study model for L-osteotomy. The normal right hip was used as a reference for performing the corrective surgery. Four FEA models were constructed using different numbers of fixation screws but the same osteotomy lengths together with four FEA models with the same number of fixation screws but different osteotomy lengths. The von Mises stress distributions and femoral head displacements were analyzed and compared.

RESULTS

The results revealed the following: 1). The fixation devices (plate and screws) sustained most of the external loading, and the peak value of von Mises stress on the fixation screws decreased with an increasing number of screws. 2). Additional screws are more beneficial on the proximal segment than on the distal segment for improving the stability of the postoperative femur. 3). The extent of osteotomy should be limited because local stress might be concentrated in the femoral neck region with increasing length of the L-osteotomy.

CONCLUSION

Additional screw placement on the proximal segment improves stability in the postoperative femur. The cobra-type plate with additional screw holes in the proximal area might improve the effectiveness of L-osteotomies.

High prevalence of coxa vara in patients with severe osteogenesis imperfecta

The purpose of this study was to determine the incidence and clinical presentation of coxa vara in 283 patients with osteogenesis imperfecta (OI). The charts and X-rays of 150 girls and 133 boys with OI were reviewed. The patients were classified according to the Sillence classification modified by Glorieux: 94 type I, 90 type IV, 67 type III, 18 type V, 10 type VI, and 4 type VII. The mean age was 9.4 years (range 0.3-23.3). Twenty-nine patients (10.2%) had coxa vara (23 left and 20 right). Fifty-five percent of them were type III, 24% type IV, 13.8% type VI, and 3.4% each of types V and VII. The incidence of coxa vara was 6% in type V, 8% in type IV, 24% in type III, 25% in type VII, and 40% in type VI (P < 0.001 for difference between types I, III, and IV). The mean neck-shaft angle was 99 degrees (range 80-110 degrees), the average head-shaft angle was 104 degrees (range 90-120 degrees), and the mean Hilgenreiner-epiphyseal angle was 68 degrees (range 40-90 degrees). Twenty-five patients (36 hips) had previous femoral rodding before diagnosis and seven hips (all type III) had no history of rodding. Abduction and internal rotation of the hip joints were restricted in all patients with this deformity. All children with coxa vara had a Trendelenburg gait. In conclusion, coxa vara in OI is not rare, especially in severe forms of the disease. Regular clinical and radiologic follow-up is indicated in children with previous femoral rodding and in severely affected children, particularly those with OI type III.

Medium-term results of the Charnley low-offset femoral stem

A reduced femoral offset in total hip replacement has been thought to be disadvantageous. We reviewed the results of 54 consecutive primary total hip replacements in 49 patients (mean age of 68 years) performed between August 1990 and December 1994, with a mean follow-up of 8.8 years (sd 2.1). The mean pre-operative femoral offset for these hips was 41 mm (sd 7.4). All patients received a low-offset Charnley stem and a polyethylene cup inserted by a single surgeon. At their latest follow-up, surviving patients had a significant improvement in the performance of their hip. Three had undergone revision, one each for deep infection, recurrent dislocation and late pain with subluxation. No hips had been revised, or were at risk of revision, for aseptic loosening. The mean annual linear rate of wear was 0.2 mm (sd 0.08) for the whole group. There was no correlation between the pre-operative femoral offset and the post-operative rate of wear. Our survivorship estimate was 91% when revision for any reason was taken as an end-point, but 100% if aseptic loosening was considered as the end-point. Our study demonstrates that a low-offset femoral stem can produce good, medium-term results.

Greater trochanteric transfer for the treatment of coxa brevis

We reviewed the outcomes of 28 patients for whom we did greater trochanteric transfer. Twenty-two (79%) patients treated for coxa brevis by greater trochanteric transfer had good relief of pain and limp. Four (1%) outcomes were fair and two (0.7%) were poor. Our outcomes compared favorably with those already reported in the literature. Patients who had avascular necrosis caused by Perthes disease tended to have a better outcome than those caused as a complication of treatment for hip dysplasia. A computer model based on radiographic measurements was useful in planning the placement of the transfer for biomechanical efficiency. The surgical technique and osteotomy planning is described. Our goal is to review (1) the effectiveness of our surgical procedure, (2) whether deformity etiology influences outcome, (3) the best way to achieve optimal biomechanical efficiency, and (4) how software assisted planning can assist in surgical planning.

[Change of offset after implantation of hip alloarthroplasties]

The purpose of the present study was to evaluate the change of the offset after implantation of hip alloarthroplasties. In an experimental study the X-ray templates of 90 different implants (594 different sizes) were digitized (cup and stem) and virtually implanted in the hip joint of 50 consecutive patients who were on the waiting list for hip replacement. Implantation was performed on AP X-rays paying heed to the fit of the shaft and adequate leg length. In total 4500 implantations were performed. After virtual implantation the change of the offset was calculated. There was a wide variance in the ability to fit the implants to the individual patient. For some patients it seems to be extremely difficult to adapt the implant without changing the offset. Some implant designs were only suitable for 2 patients while other designs were suitable for 40 patients (mean: 17). The average change of the offset was 0.27 cm. Considering only the cases in which a change occurs this value increases up to 0.56 cm.For the individual patient the average number of implants that were suitable was 30 (range: 1-67) of a total of 90 designs. Here the average change of the offset was 0.4 cm (-1.04 -- +1.54 cm). Considering only the cases in which a change occurs this value increases up to 0.64 cm. In the majority of the cases the presently available implants do not allow anatomic reconstruction of the individual offset.

Absorbable screws through the greater trochanter do not disturb physeal growth: rabbit experiments

We studied the effect of implantation of self-reinforced polyglycolic acid (SR-PGA) screws through the greater trochanter in rabbits. 15 rabbits aged 10 weeks had an SR-PGA screw inserted through the left trochanter physis. A similar drilling was made through the right greater trochanter without screw implantation. The animals were assigned to 3 groups of 5, and were killed after 1, 2 or 3 months. Radiographs of both femurs were obtained monthly and the articulo-trochanteric distance and the neck-shaft angle were measured. After killing the animals, a histological study was performed. The drilling on the right trochanter generated a bony bridge in all the animals. The SR-PGA screws did not give rise to an epiphysiodesis. The progressive peripheral degradation of the implants gave rise to the formation of only modest bridges, which were smaller in size than those observed in the control trochanter. Our findings suggest that absorbable PGA screws implanted through a growth plate cause only minor bone formation and no epiphyseodesis.