Preservation technique of the piriformis tendon is superior to reattachment technique in terms of contiguity and muscle atrophy: using magnetic resonance imaging

PURPOSE

The preservation technique of the piriformis tendon during the posterolateral approach in total hip arthroplasty (THA) is reportedly superior to the reattachment technique in terms of dislocation. However, the long-term effects of preservation of the piriformis tendon during THA remain unknown. In this study, we evaluated the contiguity of the piriformis/conjoined tendon and atrophy of the piriformis/internal obturator muscle during a long-term postoperative follow-up using magnetic resonance imaging (MRI).

METHODS

We retrospectively evaluated 48 patients with available MRI. The 48 patients were classified into a P group ( n = 29), in which the piriformis tendon was preserved, and an R group ( n = 19), in which the piriformis was reattached after sectioning. The mean follow-up duration was 45.9 months. The contiguity of the piriformis/conjoined tendon and atrophy of the piriformis/internal obturator muscle were evaluated in all patients.

RESULTS

The piriformis tendon remained attached to the greater trochanter in all P-group patients and 68.4% of R-group patients. The mean piriformis muscle atrophy ratios were 15.9% ± 21.1% in the P group and 41.6% ± 19.1% in the R group ( p < 0.001). The conjoined tendon repair remained intact in 72.4% of P-group patients and 36.8% of R-group patients ( p < 0.05). The mean internal obturator muscle atrophy ratio was 31.4% ± 26.2% in the P group and 50.4% ± 19.1% in the R group ( p < 0.05). No postoperative pulmonary embolism, wound infection, deep infection, or hip dislocation occurred.

CONCLUSIONS

In our study, we suggest that the preservation technique of the piriformis tendon is superior to the reattachment technique in terms of contiguity and muscle atrophy.

Chondrolipoma of the Ankle in a Child: A Case Report

Chondrolipoma is an extremely rare variant of lipoma with cartilaginous metaplasia. The presence of nonlipomatous components can lead to a variety of entities in the differential diagnosis from the radiologic findings. We describe an unusual case of a chondrolipoma occurring in the right ankle of a 9-year-old female. Physical examination showed a 3.5-cm, elastic-hard, poorly mobile, nontender mass adherent to the Achilles tendon. Plain radiographs revealed a faintly calcified soft tissue mass without bone involvement. Magnetic resonance imaging showed a well-defined mass with 2 components with heterogeneous signal intensity, suggesting the coexistence of a fatty area and another nonlipomatous component. Marginal excision of the tumor was performed. Histologically, the tumor was composed of mature adipose tissue studded with islands of mature hyaline cartilage. Based on these findings, the tumor was diagnosed as a chondrolipoma. The patient had no evidence of local recurrence within 9 months of follow-up. To the best of our knowledge, this is the first case of chondrolipoma originating from the ankle in a child.

Is the obturator artery safe when performing ischial osteotomy during periacetabular osteotomy?

The purposes of this study were (1) to evaluate the actual distance between the obturator artery and the ischial osteotomy site when performing periacetabular osteotomy via an anterior approach and (2) to determine a safe method to avoid injuring the obturator artery during this procedure. Twenty-nine hemipelves from cadavers were used in this study. The mean distance between the obturator artery and the ischial osteotomy site was 35.6 ± 7.5 mm and always exceeded 20 mm. Therefore, the procedure can be performed safely when a chisel blade of 20 mm or shorter is used.

Postoperative acetabular retroversion causes posterior osteoarthritis of the hip

We retrospectively reviewed 68 hips in 62 patients with acetabular dysplasia who underwent curved periacetabular osteotomy. Among the 68 hips, 33 had acetabular retroversion (retroversion group) and 35 had anteversion (control group) preoperatively. All hips were evaluated according to the Harris hip score. Radiographic evaluations of acetabular retroversion and posterior wall deficiency were based on the cross-over sign and posterior wall sign, respectively. The clinical scores of the two groups at the final follow-up were similar. In the retroversion group, 12 hips had anteverted acetabulum postoperatively. The posterior wall sign disappeared in these hips, but remained in 21 hips with retroverted acetabulum postoperatively. Among the 21 hips with retroverted acetabulum, posterior osteoarthritis of the hip developed postoperatively in five hips. When performing corrective osteotomy for a dysplastic hip with acetabular retroversion, it is important to correct the acetabular retroversion to prevent posterior osteoarthritis of the hip due to posterior wall deficiency.

Prevalence of femoroacetabular impingement in Asian patients with osteoarthritis of the hip

Although femoroacetabular impingement (FAI) has recently been considered to be one of the causes of osteoarthritis (OA) of the hip, the exact pathogeneses and incidence of FAI and primary OA are unknown. The purposes of this study were to investigate the causes of hip OA in Japan and to clarify the prevalence of FAI in patients with hip OA. We retrospectively investigated 817 consecutive patients (946 hips) who underwent primary surgery with the diagnosis of OA of the hip. Clinical recordings and preoperative radiographs were evaluated to determine the cause of OA. There were 17 hips who had primary OA, of which six hips were determined to be FAI positive. The remaining 11 cases without FAI had primary OA of unknown aetiology. Our study has revealed that most hip OA cases were caused by developmental dysplasia of the hip. We only found a few cases (0.6%) with FAI in Japan.

Which is more invasive-mini versus standard incisions in total hip arthroplasty?

In this study, interleukin-6 (IL-6), C-reactive protein (CRP), and haemoglobin levels were evaluated to compare the degree of surgical invasion between mini and standard incisions in total hip arthroplasty (THA). Sixty-two patients admitted for primary cementless THA were enrolled in this randomised study. The patients were allocated to have surgery through either a mini incision of <10 cm or a standard incision of 15 cm. In each group, inflammatory responses were evaluated by IL-6, CRP, and haemoglobin levels before operation and one day after operation. Significant differences were not found in IL-6, CRP, and haemoglobin levels between both groups. At six months after surgery, there were no significant differences in postoperative Harris hip scores or radiographic evaluations between both groups. In conclusion, a 5.0 cm difference in the skin incision to the hip joint seemed to have no influence on the degree of surgical invasion during THA.

Modified pubic osteotomy for medialization of the femoral head in periacetabular osteotomy: a retrospective study of 144 hips

BACKGROUND AND PURPOSE

Medial displacement of the femoral head reduces the force transmitted across the hip joint. Since 2005, we have performed a modified Ganz's osteotomy with curved periacetabular osteotomy (CPO) to obtain medialization of the femoral head. The modification involves cutting of the pubis at 30 degrees to the horizontal line. Here, we examined whether this modified CPO procedure medialized the femoral head more than the conventional CPO procedure.

PATIENTS AND METHODS

69 patients (mean age 37 years, 72 hips) treated with the modified CPO procedure (the M group) were compared with 68 patients (mean age 38 years, 72 hips) previously treated with conventional CPO (the C group). All patients were operated because of dysplastic hips. We used radiographic measurements from anteroposterior radiographs. The magnitude of the resultant hip force normalized with respect to the body weight (R/WB) and hip contact joint stress (Pmax/ WB) was calculated in all cases.

RESULTS

The average lateral center-edge (CE) angle, acetabular roof obliquity (ARO), and acetabulum-head index (AHI) improved in both groups. The CE angle, ARO, and AHI were similar in the 2 groups before and after surgery. Medialization of the femoral head was larger in the M group than in the C group (p < 0.001). The average value of the resultant hip force decreased from 3.2 to 2.9 in the M group and remained unchanged, at 3.1, in the C group. In addition, the average value of the peak contact stress decreased more in the M group (from 9.4 kPa/N to 3.4 kPa/N) than in the C group (from 9.1 kPa/N to 4.3 kPa/N).

INTERPRETATION

In dysplastic hips, the modified CPO reduces the contact hip stress more than the conventional CPO because of better medialization of the femoral head.

Interdigital amelanotic spindle-cell melanoma mimicking an inflammatory process due to dermatophytosis

Herein, we report a rare case of amelanotic spindle-cell melanoma on the interdigit of the left fifth toe of an 83-year-old woman. She also had tinea pedis on the same part for more than 2 years, and the part in which the tumor developed had been macerated and colonized with both Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus. Histopathologically, the biopsy specimen was indistinguishable from that of nonspecific inflammatory granulation. Two biopsies could not lead us to the correct diagnosis until the totally excised specimen was evaluated with immunohistochemical analysis including S-100 and other melanocyte markers. The patient died with multiple metastases of the tumor 18 months after her first visit. This case suggests that refractory interdigital dermatophytoses should be treated by considering the possibility of concomitant malignant neoplasms, and immunohistochemical analysis is indispensable for differential diagnosis of malignant neoplasms suggesting nonspecific granulation.

Tibiofemoral contact areas and pressures in six high flexion knees

The tibiofemoral articulating interfaces of six high flexion knee designs were examined using a standard testing protocol developed by Harris et al. [J Biomech 32:951-958 (1999)] to investigate the polyethylene insert contact areas and pressures. A load of 3600 N was applied for 10 s at 0, 30, 60, 90, 110, 135 and 155 degrees of flexion. Contact areas and pressures at the femoral-polyethylene insert interface were measured with a I-scan 4000 system. Up to 110 degrees of flexion, the VANGUARD RP HI-FLEX showed the highest contact area and lowest pressure. At the deep flexion angles, contact area decreased and contact pressure increased significantly in all knees. The NexGen series showed a constant contact area throughout the various flexion angles. In general, all high flexion knees could result in almost point contact in an extremely high range of motion.

Antibiotic distribution in a bone cement spacer model

PURPOSE

To mix high dose antibiotic powder to the bone cement more easily, Hanssen et al reported mixing the antibiotics with the cement during its liquid phase but made no comments about the relevance of cement viscosity and antibiotic distribution. The purpose of this study was to investigate the effect of the cement mixing technique and cement viscosity on the antibiotics distribution in a cement spacer model.

METHODS

Thirty cylindrical models from three groups were examined. Group A was made by mixing the antibiotics with medium viscosity cement prior to adding the liquid monomer (traditional technique). Group B was made by mixing the antibiotics with medium viscosity cement during its liquid phase (Hanssen's technique). Group C was made by traditional technique with low viscosity cement. In all groups 2 g of tetracycline was used. Three 0.1 mm thick cross sections from each spacer model were examined under the fluorescent microscope. The fluorescent spots of tetracycline were calculated automatically in pixels. To evaluate the distribution of the antibiotics in the spacer model, we selected the cross section with the highest number of pixels and the one with the lowest number of pixels from each of the three cross sections and calculated the difference between them. The distribution disequilibrium was compared between group A and B, A and C.

RESULTS

No significant difference was observed in either comparison.

CONCLUSION

The Hanssen's mixing technique can be used when using high dose antibiotics, and either medium or low viscosity cement could be used in terms of antibiotic distribution.

Curved periacetabular osteotomy for treatment of dysplastic hip

The Bernese periacetabular osteotomy has a considerable rate of postoperative complications such as reflex sympathetic dystrophy, motor nerve palsy, heterotopic ossification, and delayed union of the ilium, which are assumed to be caused by extensive exposure or asphericity of the osteotomy surfaces. To address these issues, we developed the curved periacetabular osteotomy, a modification of the Bernese periacetabular osteotomy which limits dissection, prevents the outside of the ilium from being exposed, and produces osteotomy surfaces with the same curvature. Curved periacetabular osteotomies were done on 128 hips in 118 patients whose average age at the time of surgery was 35.2 years (range, 16-59 years). The average followup was 46 months (range, 24-99 months). The average center-edge angles were 4 degrees (range, -15 degrees -5 degrees ) preoperatively and 35 degrees (20 degrees -55 degrees ) postoperatively, and union of the iliac osteotomy was achieved in all hips. We experienced three asymptomatic pubic nonunions. Dysesthesias occurred in 27 patients along the lateral femoral cutaneous nerve and symptoms resolved in 23 patients within 1 year. The average Harris hip score improved from 72 to 93 points. There were no major complications such as sciatic nerve palsy, abductor dysfunction, or heterotopic ossification.

LEVEL OF EVIDENCE

Therapeutic study, Level IV (case series--no, or historical control group). See the Guidelines for Authors for a complete description of levels of evidence.

L-shaped caliper for limb length measurement during total hip arthroplasty

The existing methods of assessing limb lengthening during total hip arthroplasty (THA) are prone to error because the measurements are not parallel to the limb lengthening axis. In order to address this, we designed a caliper to estimate limb lengthening during THA and evaluated its accuracy compared with our previous device, the straight caliper. Limb lengths were measured in 100 patients. The L-shaped caliper was used in 50 cases and the straight caliper in 50. The correlation between intra-operative and post-operative radiographic measurements was significantly improved using the L-shaped device (p < 0.0001, r = 0.934). This method was extremely accurate in predicting changes in limb length due to surgery.

Cementless total hip arthroplasty using an autograft of the femoral head for marked acetabular dysplasia: case series

PURPOSE

To assess the short-term outcome of cementless total hip arthroplasty involving an autograft of the femoral head in Japanese patients.

METHODS

Cementless total hip arthroplasty with autogenous bone block grafting was performed on 18 hips in 15 patients with marked acetabular dysplasia. The resected femoral head was used as a graft for the superior-lateral region of the true acetabulum. Clinical outcome was correlated with the placement of the acetabular component, as revealed in radiographs.

RESULTS

The 13 women and 2 men had a mean age of 60.2 years (range, 37.0-73.0 years) at primary surgery and a mean follow-up duration of 3.3 years (range, 2.0-5.3 years). According to the classification of Crowe, 4 hips were in group I, 3 were in group II, one in group III, and 10 in group IV. The mean Harris Hip Score preoperatively was 45.7 (range, 19-69) and that at follow-up was 82.5 (range, 44-100). All 15 cases showed a good clinical outcome. There were no major intra-operative complications in this series. The grafted bones united in all patients. Two patients need surgical revision because the lateral insertion of the acetabular component resulted in loosening of it.

CONCLUSION

Medial insertion of the acetabular component provides satisfactory short-term outcomes. Lateral insertion of the acetabular component during total hip arthroplasty should be avoided in patients with marked acetabular dysplasia.

A quantitative anatomic characterization of the quadrilateral surface for periacetabular osteotomy

The periacetabular osteotomy described by Ganz et al is used widely, and includes an outward osteotomy from the quadrilateral surface. Because intraarticular extension of the osteotomy can complicate the Ganz osteotomy, it is important to image the margin of the hip. To prevent this complication, and to do this procedure more safely, 32 hemipelves from cadavers were used in the current study. Some landmarks were selected that can be clarified on the quadrilateral surface during the periacetabular osteotomy. The acetabulum was hollowed out using an acetabular reamer of the same size as each femoral head, and the margin of the penetrated hole through the acetabulum was determined using these landmarks. The posterior margin of the hip is located approximately 2 cm anterior to the sciatic notch. The anatomic guidepoint for the osteotomy of the ischium averaged 14 mm inferior to the distal margin of the hip. By clarifying the margin of the hip presumed on the quadrilateral surface in this way, the periacetabular osteotomy can be done more safely, without causing complications such as intraarticular chisel penetration.

Quantitative anatomic characterisation of the pelvic brim to facilitate internal fixation through an anterior approach

PURPOSE

To define the centre of the hip joint and the bone stock around the hip joint from the supra-acetabular portion or pelvic brim so as to avoid penetration of guidewire into the hip joint when performing internal fixation using the anterior approach.

METHODS

A total of 42 cadavers were utilised. Measurements were completed before and after cutting the pelvis into 4 pieces. Before cutting the pelvis, the centre of the hip joint was measured on the pelvic brim. After cutting the pelvis, the bone stock around the hip joint was measured in each section. The pelvic brim and the anteroinferior iliac spine were utilised as guide points in the measurements, because these parameters could be determined during an anterior surgical procedure.

RESULTS

On the pelvic brim, the reflected centre of the hip joint centre was located approximately 3.2 mm anterior to the distal edge of the anteroinferior iliac spine. The mean minimum bone stock of the pelvic brim was 14.0 mm in the centre of the hip joint section.

CONCLUSION

This study described the anatomical reference points around the hip joint, and the ways in which they can be utilised to increase the safety of the anterior approach for internal fixation. It is important to define the centre of the hip joint from the supra-acetabular portion or pelvic brim, given that it is not visualised during surgery using an anterior approach.

Seroprevalence of canine dirofilariosis in South Korea

Eight-hundred and forty eight dogs (480 females and 368 males) not on chemoprophylaxis were examined for Dirofilaria immitis infection from 2001 to 2002. Three-hundred and thirty nine (40.0%) of 848 samples tested with antigen detecting ELISA kits showed positive reaction for D. immitis antigen. More male (43.5%) than female (37.3%) dogs were affected in this study, although there was no significant difference between both groups. Chi2 analysis showed that female and male dogs of shoreline areas had higher significant prevalence than other areas (P<0.001), respectively. The mean overall positive rates of heartworm infection were 10.4% in dogs <2-year-old group, 46.5% in 2-4-year-old group, 48.4% in 4-6-year-old group and 50.3% in >6-year-old group. The older the age, the higher the prevalence of D. immitis infection in this study. Chi2 analysis revealed a significant higher prevalence in 4-6-year-old group (100%) of shoreline areas and in 2-4-old-year group (51.2%) of urban areas (Chungnam province), respectively (P<0.001), and also revealed that the over 6-year-old group (50.3%) in mean overall prevalence had the significant higher prevalence than other age group (P<0.001). In climate comparison, our data showed that shoreline areas (69.5%) had the significant higher prevalence than urban areas and mountain areas (P<0.001). This survey confirms that the prevalence of canine heartworm infection increases, and also that the prevalence in shoreline areas is higher than in other areas in South Korea.

Acute effects of hip and knee positions on motor-evoked potentials of the sciatic nerve in total hip arthroplasty

In 23 patients, motor-evoked potentials (MEP) of the sciatic nerve were elicited during total hip arthroplasty by using a stimulating electrode at the level of the acetabulum and recording from the middle portion of the tibialis anterior. The distal motor latencies were determined before dislocation (control), during dislocation, and after reduction with the trial prosthesis. While the hip was dislocated, recording was performed at varying angles of the hip and knee joints. During dislocation, the distal motor latencies were significantly increased in all positions except at hip flexion of 60 degrees and internal rotation of 60 degrees with the knee joint in maximum flexion. No significant correlations were found between the latency increase and limb lengthening. No patient had sciatic nerve palsy or causalgia after operation.

Diurnal variation in microfilaremia in a cat experimentally infected with larvae of Dirofilaria immitis

In five healthy mongrel female cats used, four cats (Cats 1-4) were experimentally inoculated with 100-123 larvae (L(3)) of Dirofilaria immitis. Cat 5 was an uninfected control. Only Cat 1 became microfilaremic on Day 201 after inoculation and the diurnal changes in the microfilaria population were monitored every 2 h for 24 h on Day 237 when a sufficient number of microfilaria were detected in the circulation. The maximum number of microfilaria in the blood (1,350/ml) occurred at 9:00 p.m. and then gradually decreased to the minimum of 300/ml at 7:00 a.m., indicating that the number of microfilaria shows a nocturnal sub-periodic pattern of diurnal rhythm even in peripheral blood of cats as an abnormal host. On postmortem examination, 10 live adult worms (three males and seven females) in Cat 1 and one live adult worm (one male) in Cat 2 were detected.

In vivo study of acute effects of hip and knee positions on blood flow in canine sciatic nerve

We studied blood flow in the canine sciatic nerve using a laser Doppler flowmeter. Blood flow was measured in 20 hind limbs of ten adult dogs at varying angles of hip flexion, hip rotation and knee flexion. Blood flow decreased as flexion and internal rotation of the hip increased and also with only slight flexion of the knee. With 90 degrees knee flexion, the mean blood flow did not change significantly when the hip was internally rotated from 0 degrees to 30 degrees. When the knee was straight, the blood flow changed significantly during the same procedure. To prevent sciatic nerve palsy, attention should be paid to the positioning of the hip and knee during total hip arthroplasty.

Immunohistochemical detection of p53 and c-myc proteins in canine mammary tumours

The objectives of this study were to detect by immunohistochemical means, nuclear accumulations of p53 and c-myc proteins in mammary tumours of dogs. Moderate or intense p53 protein nuclear labelling was shown by each of five osteosarcomas. In contrast, focal immunoreactivity was shown by three of five adenocarcinomas and two of three malignant myoepitheliomas. Six benign mixed tumours and three myoepitheliomas showed no detectable immunoreactivity. On the other hand, three patterns of c-myc protein nuclear reactivity were observed in these tumours. Osteosarcomas, adenocarcinomas, malignant myoepitheliomas and myoepitheliomas showed intense or moderate reactivity. In benign mixed tumours, the epithelial component showed moderate or intense reactivity, and the myoepithelial component showed focal or moderate reactivity. These results demonstrated that p53 protein was expressed only in the osteosarcomas, but that c-myc expression was detectable in both the epithelial and myoepithelial components.

Seasonal periodical appearance of Hepatozoon canis gamont in the peripheral blood

We investigated the appearance of gamonts in peripheral leukocytes of 13 Hepatozoon canis infected dogs from June 1990 to December 1992. In almost all the dogs, the numbers of gamonts increased from spring to autumn, and decreased from autumn to winter. Particularly in the dogs used for hare hunting, a large number of gamonts was detected from spring to autumn. This finding reveals that the gamont increases in number in the dog which ingested the infected ticks during the hunting season.