Injection or aspiration of the ankle may be performed through either an anteromedial or an anterolateral approach for diagnostic or therapeutic reasons. We evaluated the success of an intra-articular puncture in relation to its site in 76 ankles from 38 cadavers. Two orthopaedic surgical trainees each injected methylene blue dye into 18 of 38 ankles through an anterolateral approach and into 20 of 38 through an anteromedial. An arthrotomy was then performed to confirm the placement of the dye within the joint. Of the anteromedial injections 31 of 40 (77.5%, 95% confidence interval (CI) 64.6 to 90.4) were successful as were 31 of 36 (86.1%, 95% CI 74.8 to 97.4) anterolateral injections. In total 62 of 76 (81.6%, 95% CI 72.9 to 90.3) of the injections were intra-articular with a trend towards greater accuracy with the anterolateral approach, but this difference was not statistically significant (p = 0.25). In the case of trainee A, 16 of 20 anteromedial injections and 14 of 18 anterolateral punctures were intra-articular. Trainee B made successful intra-articular punctures in 15 of 20 anteromedial and 17 of 18 anterolateral approaches. There was no significant difference between them (p = 0.5 and p = 0.16 for the anteromedial and anterolateral approaches, respectively). These results were similar to those of other reported studies. Unintended peri-articular injection can cause complications and an unsuccessful aspiration can delay diagnosis. Placement of the needle may be aided by the use of ultrasonographic scanning or fluoroscopy which may be required in certain instances

Recent National Institute for Health and Care Excellence (NICE) guidance has advised against the continued use of the Thompson implant when performing hip hemiarthroplasty and recommended surgeons consider using the anterolateral surgical approach over a posterior approach. Our objective was to review outcomes from a consecutive series of Thompson hip hemiarthroplasty procedures performed in our unit and to identify any factors predicting the risk of complications. 807 Thompson hip hemiarthroplasty cases performed between April 2008 and November 2013 were reviewed. 721 (89.3%) were cemented and 86 (10.7%) uncemented. 575 (71.3%) were performed in female patients. The anterolateral approach was performed in 753 (93.3%) and the posterior approach with enhanced soft tissue repair in 54 (6.7%). Overall, there were 23 dislocations (2.9%). Dislocation following the posterior approach occurred in 13.0% (7 of 54) in comparison to 2.1% (16 of 753) with the anterolateral approach (odds ratio (OR) 8.5 (95% CI 2.8 to 26.3) p < 0.001). Surgeon grade and patient history of cognitive impairment did not have a significant impact on dislocation rate. Patients were discharged home in 459 cases (56.9%), to a care home or other hospital in 273 cases (33.8%). 51.8% (338 of 653) returned home within 30 days. 75 died during their admission (9.3%). 30-day mortality was 7.1% and 1-year mortality was 16.6%. Intraoperative fracture occurred in 15 cases (1.9%) of which 14 were cemented. Superficial or deep infection occurred in 33 cases (4.1%). We recommend against the continued use of the posterior approach in hip hemiarthroplasty, as enhanced soft tissue repair did not reduce dislocation rates to an acceptable level. Our findings, however, demonstrate satisfactory results for patients treated with the Thompson hip hemiarthroplasty performed through an anterolateral approach. We suggest that the continued use of the Thompson implant in a carefully selected patient cohort is justifiable

Introduction and Objective. Heterotopic ossification is the formation of extraskeletal mineralized tissue commonly associated with either trauma or surgery. While several mouse models have been developed to better characterize the pathologic progression of HO, no model currently exists to study HO of the hip, the most common location of acquired HO in patients. Owing to the unique biological mechanisms underpinning the formation of HO in different tissues, we sought to develop a model to study the post-surgical HO of the hip. Materials and Methods. Wild-type mice C57BL/6J mice were used to study the procedure outcomes, while Pdgfra-CreERT2;mT/mG and Scx-GFP reporter animals were used for the lineage tracing experiments (total n=16 animals, male, 12 weeks old). An anterolateral approach to the hip was performed. Briefly, a 2 cm incision was made centered on the great trochanter and directed proximal to the iliac crest and distally over the lateral shaft of the femur. The joint was then reached following the intermuscular plane between the rectus femoris and gluteus medius muscles. After the joint was exposed, the articular cartilage was removed using a micropower drill with a 1.2 mm reamer. The medius gluteus and superficial fascia were then re-approximated with Vicryl 5-0 suture (Ethicon Inc, Somerville, NJ) and skin was then closed with Ethilon 5-0 suture (Ethicon Inc). Live high resolution XR imaging was performed every 2 wks to assess the skeletal tissues (Faxitron Bioptics, Tucson, AZ). The images were then scored using the Brooker classification. Ex-vivo microCT was conducted using a Skyscan 1275 scanner (Bruker-MicroCT, Kontich, Belgium). 3D reconstruction and analysis was performed using Dragonfly (ORS Inc., Montreal, Canada). For the histological analysis of specimens, Hematoxylin and Eosin (H&E), modified Goldner's Trichrome (GMT) stainings were performed. Reporter activity was assessed using fluorescent imaging. Results. Substantial periarticular heterotopic bone was seen in all cases. A periosteal reaction and an initial formation of calcified tissue within the soft tissue was apparent starting from 4 wks after surgery. By XR, progressive bone formation was observed within the periosteum and intermuscular planes during the subsequent 8 weeks. Stage 1 HO was observed in 12.5% of cases, stage 2 in 62.5% of cases, and stage 3 HO in 25% of cases. 3D microCT reconstructions of the treated hip joints demonstrated significant de novo heterotopic bone in several location which phenocopy human disease. Heterotopic bone was observed in an intracapsular location, periosteal location involving the iliac bone and proximal femur, and intermuscular locations. Histological analyses further confirmed these findings. To assess the cells which gave rise to HO in this model, an inducible PDGFRα and constitutive Scx-GFP reporter mice were used. A dramatic increase in mGFP reporter activity was noted PDGFRα within the HO injury site, including in areas of new cartilage and bone formation. Scx-associated reporter activity increased in the soft tissue and periosteal periacetabular areas of injured hips. Conclusions. HO has a diverse set of pathologies, of which joint associated HO after elective surgery is the most common. Here, we present the first mouse model of hip dislocation and acetabular reaming that mimics elements of human periarticular HO. The diverse locations of HO after acetabular reaming (intracapsular, intermuscular and periosteal) suggests the activation of different and specific HO program after surgery. Such a field effect would be consistent with local trauma and inflammation, which is a well-studied contributor to HO genesis. Not surprisingly, joint-associated HO significantly derives from PDGFRα-expressing cells, which has been shown to similarly give rise to intramuscular and intratendinous HO

Identification of gait deviations and compensations in patients with total hip arthroplasty (THA) is important for the management of their fall risks. To prevent collapse of the lower limbs while balancing and supporting the body, proper combinations of joint moments are necessary. However, hip muscles affected by THA may compromise the sharing of load and thus the whole body balance. The current study aimed to quantify the control of body support in patients with THA in terms of the total support moment (Ms) and contributions of individual joint moments to Ms during walking. Six patients who underwent unilateral THA via an anterolateral approach for at least six months at the time of the gait experiment, and six age- and gender-matched healthy controls were recruited. Twenty-eight infrared retro-reflected markers were placed on specific landmarks of the pelvis-leg apparatus to track the motion of the segments during walking. Kinematic and kinetic data were measured using an 8-camera motion analysis system (Vicon, Oxford Metrics, U.K.) and two force plates (AMTI, U.S.A.). The Ms of a limb was calculated as the sum of the net extensor moments at the hip, knee and ankle during stance phase. The contributions of the hip, knee and ankle to the first and second peaks of Ms (Ms1 and Ms2) were calculated by dividing the joint moment value by the corresponding peak values of Ms. Independent t-tests were performed to compare between groups at a significance level set at α=0.05 using SAS version 9.2 (SAS Institute Inc., NC, USA). No significant differences in Ms1 and Ms2 were found between the THA group and normal controls (P >0.05). However, compared to the healthy controls, significantly increased hip and ankle contributions but decreased knee contributions to Ms1, and significantly increased hip contributions but decreased ankle contributions to Ms2 were found in the THA group. Similar Ms1 and Ms2 between groups indicates that the lower limbs in the THA group were able to provide normal body supports. However, this was achieved via an altered contributions of the hip, knee and ankle. Hip and knee extensors play important roles in supporting the body when the Ms1 occurs during early stance of walking. In the THA group, greater hip and ankle contributions but lesser knee contributions for the Ms1 indicates that the function of hip extensors were not affected but compensatory mechanisms of the knee and ankle were found. For the Ms2, hip flexor and ankle plantarflexors are important for supporting the body during late stance. Decreased hip flexor (i.e., greater hip extensor contributions) and ankle plantarflexor moments in the THA patients suggests that the hip flexors and ankle plantarflexor muscles were affected by THA surgery. Hip muscles affected by the THA may compromise the sharing of load at the hip and thus the whole body balance. Further postoperative rehabilitation is suggested for the patients following THA. Further studies on the effects of different surgical approaches on the support moments is needed for improving treatment plans

Introduction. The purpose of this study was to evaluate the functional and radiographical results in patients who underwent a modified minimally invasive two-incision total hip arthroplasty using large-diameter ceramic-on-ceramic articulations for osteonecrosis of the femoral head. Methods. One hundred and one patients (135 hips) who underwent unilateral minimally invasive two-incision total hip arthroplasties using large diameter ceramic-on-ceramic bearings for osteonecrosis of the femoral head with a minimum 12-months follow-up were included in this study. There were 22 women and 79 men who had a mean age of 46 years (range, 22 to 82 years). The mean follow-up was 25 months (range, 12 to 36 months). All surgeries were done by a single hip surgeon. The authors modified the original minimally invasive two-incision total hip arthroplasty technique and used large-diameter (32mm, 36mm) ceramic-on-ceramic articulations. In the lateral position, an anterolateral approach between the gluteus medius and tensor fascia lata muscles and a posterior approach between the piriformis and gluteus medius muscles was used. Functional results were measured by Harris hip (HHS) and WOMAC scores. Radiographic evaluation was assessed for positioning of the components and complications were assessed. Results. The mean Harris hip score improved from 43 points (range, 13 to 58 points) pre-operatively to 96 points (range, 73 to 100 points) post-operatively and the mean WOMAC score improved from 67 points (range, 50 to 98 points) to 28 points (range, 26 to 39 points). On radiological evaluation, the mean lateral opening angle of the acetabular component was 35.9 degrees (range, 27.1 degrees to 47.4 degrees) and the mean stem position was valgus 2.4 degrees (range, varus 2.7 degrees to valgus 5.3 degrees). One patient suffered an intra-operative femur fracture and another underwent revision surgery due to stem subsidence. There were no complications such as immediate post-operative deep infection, delayed infection, or recurrent dislocation. Conclusion. A modified minimally invasive two-incision total hip arthroplasty using large-diameter ceramic-on-ceramic articulation for osteonecrosis of the femoral head is safe and reproducible in terms of achieving proper implant positioning and early functional recovery. In particular, the complication rates encountered, especially dislocation, were low

Introduction. The purpose of this study was to evaluate the functional and radiographical results in patients who underwent a modified minimally invasive two-incision total hip arthroplasty using large-diameter metal-on-metal articulations for osteonecrosis of the femoral head. Methods. From December 2007 to July 2008, 45 hips (33 patients) underwent total hip arthroplasty for the treatment of osteonecrosis of the femoral head. There was 1 woman (2 hips) and 32 men (43 hips) who had a mean age of 39 years (range, 22 to 64 years). The minimum follow-up was 12 months (range, 12 to 19 months). The authors modified the original minimally invasive two-incision total hip arthroplasty technique and used large-diameter metal-on-metal articulations. In the lateral position, an anterolateral approach was used between the gluteus medius and tensor fascia lata muscles and for the posterior approach the muscle plane was between the piriformis and gluteus medius muscles. The acetabular components, Durom¯ (Zimmer) in 20 hips and Magnum¯ (Biomet) was used in 25 hips. M/L taper¯ (Zimmer) femoral stems were used in all cases. The size of the femoral heads were 38 mm (1 hip), 40 mm (3 hips), 42 mm (13 hips), 44 mm (18 hips), 46 mm (5 hips), 48 mm (4 hips) and 50 mm (1 hip). Postures such as excessive flexion or adduction which cause dislocation were not restricted, post-operatively. Functional results were measured by Harris hip scores (HHS), WOMAC scores, and range of motion. Radiographic evaluation was assessed for positions of components and post-operative complications were noted. Results. Mean operation time was 72 minutes (range, 54 to 94 minutes). The mean Harris hip score improved from 50 points (range, 38 to 73 points) pre-operatively to 96 points (range, 84 to 100 points) post-operatively, and the mean WOMAC score improved from 68 points (range, 50 to 93 points) to 28 points (range, 26 to 34 points). The mean flexion improved from 85° pre-operatively to 122° post-operatively. The mean internal rotation improved from 2.5° pre-operatively to 25.3° post-operatively. The mean external rotation improved from 31.8° pre-operatively to 60.1° post-operatively. The mean abduction improved from 24.0° pre-operatively to 41.6° post-operatively. The mean adduction improved from 19.4 ° pre-operatively to 26.6° post-operatively. All patients were able to sit cross legged and squat. On radiological evaluation, the mean lateral opening angle of the acetabular component was 39.4° (range, 32.2°-48.5°) and the mean stem position was valgus 0.3° (range, varus 2.8° to valgus 2.0°). At last follow-up, all femoral and acetabular components were well-fixed without loosening or subsidence. There were no complications such as dislocation, immediate post-operative deep infection or delayed infection. Conclusion. Modified minimally invasive two-incision total hip arthroplasty using large-diameter metal-on-metal articulations for osteonecrosis of the femoral head results in satisfactory early clinical and radiologic results

A complete cement mantle is important for the longevity of a total hip replacement. In the minimally-invasive direct anterior approach used at the Innsbruck University hospital, the femoral component has to be inserted into the femoral canal by an angulated movement. In a cadaver study, the quality and the extent of the cement mantle surrounding 13 Exeter femoral components implanted straight through a standard anterolateral transgluteal approach were compared with those of 13 similar femoral components implanted in an angulated fashion through a direct anterior approach. A third-generation cementing technique was used. The inner and outer contours of the cement mantles was traced from CT scans and the thickness and cross-sectional area determined. In no case was the cement mantle incomplete. The total mean thickness of the cement mantle was 3.62 mm (95% confidence interval 3.59 to 3.65). The mean thickness in the group using the minimally-invasive approach was 0.16 mm less than that in the anterolateral group. The distribution of the thickness was similar in the two groups. The mean thickness was less on the anteromedial and anterolateral aspect than on the posterior aspect of the femur. There is no evidence that the angulated introduction of Exeter femoral components in the direct anterior approach in cadavers compromises the quality, extent or thickness of the cement mantle

We have developed an animal model to examine the formation of heterotopic ossification using standardised muscular damage and implantation of a beta-tricalcium phosphate block into a hip capsulotomy wound in Wistar rats. The aim was to investigate how cells originating from drilled femoral canals and damaged muscles influence the formation of heterotopic bone. The femoral canal was either drilled or left untouched and a tricalcium phosphate block, immersed either in saline or a rhBMP-2 solution, was implanted. These implants were removed at three and 21 days after the operation and examined histologically, histomorphometrically and immunohistochemically.

Bone formation was seen in all implants in rhBMP-2-immersed, whereas in those immersed in saline the process was minimal, irrespective of drilling of the femoral canals. Bone mineralisation was somewhat greater in the absence of drilling with a mean mineralised volume to mean total volume of 18.2% (sd 4.5) versus 12.7% (sd 2.9, p < 0.019), respectively.

Our findings suggest that osteoinductive signalling is an early event in the formation of ectopic bone. If applicable to man the results indicate that careful tissue handling is more important than the prevention of the dissemination of bone cells in order to avoid heterotopic ossification.

We describe a lateral approach to the distal humerus based on initial location of the superficial branches of the radial nerve, the inferior lateral cutaneous nerve of the arm and the posterior cutaneous nerve of the forearm. In 18 upper limbs the superficial branches of the radial nerve were located in the subcutaneous tissue between the triceps and brachioradialis muscles and dissected proximally to their origin from the radial nerve, exposing the shaft of the humerus. The inferior lateral cutaneous nerve of the arm arose from the radial nerve at the lower part of the spiral groove, at a mean of 14.2 cm proximal to the lateral epicondyle. The posterior cutaneous nerve of the forearm arose from the inferior lateral cutaneous nerve at a mean of 6.9 cm (6.0 to 8.1) proximal to the lateral epicondyle and descended vertically along the dorsal aspect of the forearm. The size and constant site of emergence between the triceps and brachioradialis muscles constitute a readily identifiable landmark to explore the radial nerve and expose the humeral shaft.

Our aim was to assess the intra- and inter-observer reliability in the establishment of the anterior pelvic plane used in imageless computer-assisted navigation. From this we determined the subsequent effects on version and inclination of the acetabular component.

A cadaver model was developed with a specifically-designed rod which held the component tracker at a fixed orientation to the pelvis, leaving the anterior pelvic plane as the only variable. Eight surgeons determined the anterior pelvic plane by palpating and registering the bony landmarks as reference points. The exact anterior pelvic plane was then established by using anatomically-placed bone screws as reference points.

The difference between the surgeons was found to be highly significant (p < 0.001). The variation was significantly larger for anteversion (sd 9.6°) than for inclination (sd 6.3°). The present method for registering pelvic landmarks shows significant inaccuracy, which highlights the need for improved methods of registration before this technique is considered to be safe.

An experimental sheep model was used for impaction allografting of 12 hemiarthroplasty femoral components placed into two equal-sized groups. In group 1, a 50:50 mixture of ApaPore hydroxyapatite bone-graft substitute and allograft was used. In group 2, ApaPore and allograft were mixed in a 90:10 ratio. Both groups were killed at six months. Ground reaction force results demonstrated no significant differences (p > 0.05) between the two groups at 8, 16 and 24 weeks post-operatively, and all animals remained active. The mean bone turnover rates were significantly greater in group 1, at 0.00206 mm/day, compared to group 2 at 0.0013 mm/day (p < 0.05). The results for the area of new bone formation demonstrated no significant differences (p > 0.05) between the two groups. No significant differences were found between the two groups in thickness of the cement mantle (p > 0.05) and percentage ApaPore-bone contact (p > 0.05).

The results of this animal study demonstrated that a mixture of ApaPore allograft in a 90:10 ratio was comparable to using a 50:50 mixture.