Hip resurfacing arthroplasty (HRA) in patients with a varus deformity of the femoral neck-shaft angle (NSA) has been cited in the literature as contributory factor towards a poorer outcome. Our experience has not reflected this. We examined the outcomes of patients with varus hips against a normal cohort. Measurement of the femoral neck-shaft angle was undertaken from standard antero-posterior radiographs pre-operatively. The mean NSA was 128.5 degrees (SD 6.3). Patients less than 122.2 were deemed varus and those above 134.8 valgus. These parameters were consistent with the published literature. The varus cohort consisted of 23 patients, mean NSA 118.7 (range 113.6-121.5), mean follow-up 49 months (range 13-74), mean OHS & HHS, 16 & 93.5 respectively. Complications included 2 cases of trochanteric non-union; no femoral neck fractures or revisions. The normal cohort consisted of 125 patients, mean NSA 128 degrees, mean follow-up 41 months (range 6-76), mean OHS & HSS, 18.8 & 88.9 respectively. Complications included 5 cases of trochanteric non-union and 1 revision. Statistical analysis demonstrated no difference between the cohorts OHS (p=0.583) or HHS (p=0.139). Our experience in patients with a varus femoral neck has been positive. Our analysis has demonstrated no difference in outcomes between the cohorts

Hip resurfacing arthroplasty (HRA) in patients with a varus deformity of the femoral neck-shaft angle (NSA) is associated with poorer outcomes. Our experience has not reflected this. We examined the Oxford Hip Scores (OHS), Harris Hip Scores (HHS) and outcomes of patients with varus hips against a normal cohort to ascertain any significant difference. We identified 179 patients. Measurement of the femoral neck-shaft angle was undertaken from antero-posterior radiographs pre-operatively. The mean NSA was 128.5 degrees (SD 6.3). Patients with a NSA of less than 122.2 were deemed varus and those above 134.8 valgus. These parameters were consistent with published anatomical studies. The varus cohort consisted of 23 patients, mean NSA 118.7 (range 113.6-121.5), mean follow-up 49 months (range 13-74). Mean OHS and HHS were 16 and 93.5 respectively. Complications included 2 cases of trochanteric non-union; no femoral neck fractures, early failures or revisions. Normal cohort consisted of 125 patients, mean NSA 128 degrees, mean follow-up 41 months (range 6-76). The OHS and HSS were 18.8, 88.9 respectively. Complications included 5 trochanteric non-unions and 1 revision due to an acetabular fracture following a fall. Statistical analysis demonstrated no statistical difference between the cohorts OHS (p=0.583) or HHS (p=0.139). Our experience in patients with a varus femoral neck has been positive. Our analysis has demonstrated no statistical difference in hip scores between the cohorts. We have not yet experienced any femoral neck fractures, which we believe is due to the use of the Ganz trochanteric flip and preservation of blood supply

Introduction. Reverse total shoulder arthroplasty (RTSA) can partially restore lost range of motion (ROM). Active motion restoration is largely a function of RTSA joint constraint, limiting impingement, and muscle recruitment; however, it may also be a function of implant design. The aim of this computational study was to examine the effects of implant design parameters, such as neck-shaft (N-S) angle and glenoid lateralization, on impingement-free global circumduction range of motion (GC-ROM). GC-ROM summarizes the characteristically complex, wide-ranging envelope of glenohumeral motion into a single quantity for ease of comparison. Methods. Nine computational models were used to investigate implant parameters. The parameters examined were N-S angles of 135°, 145°, and 155° in combination with glenoid lateralizations (0, 5, and 10 mm). Static positioning of the humerus was defined by an elevation direction angle, elevation angle, and rotation. The humerus was rotated from the neutral position (0° of rotation and elevation), and then elevated in different elevation directions until impingement was detected. Abduction occurred at an elevation direction angle of 0°, while flexion and extension occurred at elevation direction angles of 90° and −90°, respectively. Elevation direction angles ranged from −180° to 180°. Elevation ranged from 0° and 180°. Rotations ranged from −45° to 90°, where negative and positive rotations represented external and internal rotation, respectively. For each rotation angle, a plot of maximum elevation in each elevation plane was created using polar coordinates (radius = elevation, angle = elevation direction). The area enclosed by the resulting points, normalized with respect to the implant with a 145° N-S angle and 5 mm lateralization, was calculated. The sum of these areas defined the GC-ROM. Results. Figure 1 depicts the maximum ROM curves at each angle of rotation for a 145° N-S angle humeral implant with 5 mm of glenoid lateralization. Table 1 shows the normalized areas within the maximum ROM curves for each implant configuration at each angle of rotation, where 0% indicates that the corresponding angle of rotation could not be achieved without impingement. The effect of varying N-S angle (constant lateralization of 5 mm) and lateralization (constant N-S angle of 145°) is shown for 0° rotation (Figures 2A and 2B, respectively). Conclusions. In general, increasing glenoid lateralization increases GC-ROM; however, the unintuitive poor performance of all 10 mm lateralized configurations at rotations of −90° highlights the complex relationships between implant parameters and ROM. Interestingly, the 135° N-S implant had greater flexion and extension ROM, while the 155° N-S implant had greater abduction ROM, suggesting that there are trade-offs between N-S angles pertaining to the elevation direction in which maximum elevation is obtained. The results of this study highlight the need to incorporate multi-directional motion when assessing the effect of varying implant parameters on the impingement-free GC-ROM. Future studies will include the application of the presented technique to a broader range of implant and surgical parameters

Atypical femoral fracture non-union (AFFNU) is both, rare (3–5 per 1000 proximal femur fractures) and difficult to treat. Lack of standardised guidelines leads to a variability in fixation constructs, use of bone grafting and restricted weight bearing protocols, which are not evidence based. We hypothesised that there is no change in union rates without the use of bone grafting and immediate weight bearing post-operatively does not lead to increased complications. Materials & Methods. A retrospective review of all consecutively treated AFFNU cases between March 2015 to December 2019 was carried out. 9 patients with a mean age of 63.87 years and M:F ratio of 7:2 met the inclusion criteria. Primary outcome variable was radiographic union at 12 months after revision surgery. All surgeries were carried out by a single surgeon. Fixation construct, neck-shaft angle, use of bone graft and immediate postoperative weight bearing protocols were recorded. Results. Radiographic union was achieved in 7 of 9 patients (78%) after first revision surgery. 1 patient achieved union after 2nd revision surgery and 1 patient died in the early post-operative period due to pulmonary embolism. No bone grafting was used in any of the patients and weight-bearing as tolerated was allowed from the first post-operative day. The mean neck-shaft angle after non-union surgery was 136 degrees. Conclusions. In this case series, the union rate was comparable to those reported in literature previously and achieved without any form of bone grafting. To our knowledge, this is the only case series where no bone grafting was used in the management of AFFNU. Limited by a small sample size and retrospective study design, still, this study brings into question the efficacy of practice of bone grafting and restricted weight-bearing in the management of AFFNU. Bone grafting is associated with the risk of infection at donor site, postoperative pain, and morbidity, while early weight bearing is critical in elderly patients. There is no evidence supporting restricted weight-bearing and it should not be adopted as the default practice as it may even be detrimental to patients

Objective. To three-dimensionally reconstruct the proximal femur of DDH (Developmental dysplasia of the hip) and measure the related anatomic parameters, so that we could have a further understanding of the morphological variation of the proximal femur of DDH, which would help in the preoperative planning and prosthesis design specific for DDH. Methods. From Jan.2012 to Dec.2014, 38 patients (47 hips) of DDH were admitted and 30 volunteers (30 hips) were selected as controls. All hips from both groups were examined by CT scan and radiographs. The Crowe classification method was applied. The CT data were imported into Mimics 17.0. The three-dimensional models of the proximal femur were then reconstructed, and the following parameters were measured: neck-shaft angle, neck length, offset, height of the centre of femoral head, height of the isthmus, height of greater trochanter, the medullary canal diameter of isthmus(Di), the medullary canal diameter 10mm above the apex of the lesser trochanter(DT+10), the medullary canal diameter 20mm below the apex of the lesser trochanter(DT-20), and then DT+10/Di, DT-20/Di and DT+10/DT-20 were calculated. Results. There is no significant difference in neck-shaft angle between Crowe I-III DDH and the control group, while the neck-shaft angle is much smaller in Crowe IV DDH. The neck length of Crowe IV DDH is much smaller than those of Crowe I-III DDH. As for Di there is neither significant difference between Crowe I DDH and the control group, nor significant difference between CroweII-III and Crowe IV, but the difference is significant between the first two groups and the latter two groups. DT+10/DT-20 and the offset have no significant difference between the control group and DDH groups. DT-20, DT+10, DT+10/Di and DT-20/Di are much smaller in Crowe IV DDH than that in Crowe I-III and the control groups. Height of greater trochanter in Crowe IV is larger than those in Crowe I-III and the control group. Height of the centre of femoral head in Crowe IV DDH is smaller than those in Crowe I-III DDH and the control group. The height of the isthmus in Crowe IV is much smaller than those in Crowe I-III DDH and the control group. Conclusion. The neck-shaft angle in DDH groups is not larger than that in the control group, while in contrast, it's much smaller in Crowe IV DDH than that in the control group. Comparing to Crowe I-III DDH and the control group, Crowe IV DDH has a dramatic change in the intramedullary and extramedullary parameters. The isthmus and the great trochanter are higher and there is apparent narrowing of the medullary canal around the level of the lesser trochanter

With the growing number of individuals with asymptomatic cam-type deformities, elevated alpha angles alone do not always explain clinical signs of femoroacetabular impingement (FAI). Differences in additional anatomical parameters may affect hip joint mechanics, altering the pathomechanical process resulting in symptomatic FAI. The purpose was to examine the association between anatomical hip joint parameters and kinematics and kinetics variables, during level walking. Fifty participants (m = 46, f = 4; age = 34 ± 7 years; BMI = 26 ± 4 kg/m²) underwent CT imaging and were diagnosed as either: symptomatic (15), if they showed a cam deformity and clinical signs; asymptomatic (19), if they showed a cam deformity, but no clinical signs; or control (16), if they showed no cam deformity and no clinical signs. Each participant's CT data was measured for: axial and radial alpha angles, femoral head-neck offset, femoral neck-shaft angle, medial proximal femoral angle, femoral torsion, acetabular version, and centre-edge angle. Participants performed level walking trials, which were recorded using a ten-camera motion capture system (Vicon MX-13, Oxford, UK) and two force plates (Bertec FP4060–08, Columbus, OH, USA). Peak sagittal and frontal hip joint angles, range of motion, and moments were calculated using a custom programming script (MATLAB R2015b, Natick, MA, USA). A one-way, between groups ANOVA examined differences among kinematics and kinetics variables (α = 0.05), using statistics software (IBM SPSS v.23, Armonk, NY, USA); while a stepwise multiple regression analysis examined associations between anatomical parameters and kinematics and kinetics variables. No significant differences in kinematics were observed between groups. The symptomatic group demonstrated lower peak hip abduction moments (0.12 ± 0.08 Nm/kg) than the control group (0.22 ± 0.10 Nm/kg, p = 0.01). Sagittal hip range of motion showed a moderate, negative correlation with radial alpha angle (r = −0.33, p = 0.02), while peak hip abduction moment correlated with femoral neck-shaft angle (r = 0.36, p = 0.009) and negatively with femoral torsion (r = −0.36, p = 0.009). With peak hip abduction moment in the stepwise regression analysis, femoral torsion accounted for a variance of 13.3% (F(1, 48) = 7.38; p = 0.009), while together with femoral neck-shaft angle accounted for a total variance of 20.4% (R² change = 0.07, F(2, 47) = 6.01; p = 0.047). Although elevated radial alpha angles may have limited sagittal range of motion, the cam deformity parameters did not affect joint moments. Femoral neck-shaft angle and femoral torsion were significantly associated with peak hip abduction moment, suggesting that the insertion location of the abductor affects muscle's length and its resultant force vector. A varus neck angle, combined with severe femoral torsion, may ultimately influence muscle moment arms and hip mechanics in individuals with cam FAI

Introduction. Reverse total shoulder arthroplasty continues to have a high complication rate, specifically with component instability and scapular notching. Therefore, the purpose of this study was to quantify the effects of humeral component neck angle and version on impingement free range of motion. Methods. A total of 13 cadaveric shoulders (4 males and 9 females, average age = 69 years, range 46 to 96 years) were randomly assigned to two studies. Study 1 investigated the effects of humeral component neck angle (n=6) and Study 2 investigated the effects of humeral component version (n=7). For all shoulders, Tornier Aequalis® Reversed Shoulder implants (Edina, MN) were used. For study 1, the implants were modified to 135, 145 and 155 degree humeral neck shaft angles and for Study 2 a custom implant that allowed control of humeral head version were used. For biomechanical testing, a custom shoulder testing system that permits independent loading of all shoulder muscles with six degree of freedom positioning was used. (Figure 1) Internal control experimental design was used where all conditions were tested on the same specimen. Study 1. The adduction angle and internal/external humeral rotation angle at which impingement occurred were measured. Glenohumeral abduction moment was measured at 0 and 30 degrees of abduction, and anterior dislocation forces were measured at 30 degrees of internal rotation, 0 and 30 degrees of external rotation with and without subscapularis loading. Study 2. The degree of internal and external rotation when impingement occurred was measured at 0, 30 and 60 degrees of glenohumeral abduction in the scapular plane with the humeral component placed in 20 degrees of anteversion, neutral version, 20 degrees of retroversion, and 40 degrees of retroversion. Statistical analysis was performed with a repeated measures analysis of variance with a Tukey post-hoc test with a significance level of 0.05. Results. Study 1. Adduction deficit angles for 155, 145, and 135 degree neck-shaft angle were 2 ± 5 degrees of abduction, 7 ± 4 degrees of adduction, and 12 ± 2 degrees of adduction (P <0.05), respectively. Impingement-free angles of humeral rotation and abduction moments were not statistically different between the neck-shaft angles. The anterior dislocation force was significantly higher for the 135degree neck-shaft angle at 30 degrees of external rotation and significantly higher for the 155 degree neck shaft angle at 30 degrees of internal rotation (P<.01). The anterior dislocation forces were significantly higher when the subscapularis was loaded (P <0.01). Study 2. Maximum external rotation was the limiting position for impingement particularly at 0 degrees of abduction. Maximum external rotation before impingement occurred increased significantly with increasing humeral retroversion (p < 0.05) (Figure 2). No impingement or subluxation occurred at any humeral version in 60 degrees of glenohumeral abduction. Conclusion. In reverse shoulder arthroplasty, 155 degree neck-shaft angle was more prone to impingement with adduction but had the advantage of being more stable. In addition, 40 degrees of retroversion has the largest range of humeral rotation without impingement

Scapular notching is a common problem following reverse shoulder arthroplasty (RSA). This is due to impingement between the humeral polyethylene cup and scapular neck in adduction and external rotation. Various glenoid component strategies have been described to combat scapular notching and enhance impingement-free range of motion (ROM). There is limited data available detailing optimal glenosphere position in RSA with an onlay configuration. The purpose of this study was to determine which glenosphere configurations would maximise impingement free ROM using an onlay RSA prosthesis. A three-dimensional (3D) computed tomography (CT) scan of a shoulder with Walch A1, Favard E0 glenoid morphology was segmented using validated software. An onlay RSA prosthesis was implanted and a computer model simulated external rotation and adduction motion of the virtual RSA prosthesis. Four glenosphere parameters were tested; diameter (36mm, 41mm), lateralization (0mm, 3mm, 6mm), inferior tilt (neutral, 5 degrees, 10 degrees), and inferior eccentric positioning (0.5mm, 1.5mm. 2.5mm, 3.5mm, 4.5mm). Eighty-four combinations were simulated. For each simulation, the humeral neck-shaft angle was 147 degrees and retroversion was 30 degrees. The largest increase in impingement-free range of motion resulted from increasing inferior eccentric positioning, gaining 15.0 degrees for external rotation and 18.8 degrees for adduction. Glenosphere lateralization increased external rotation motion by 13. 6 degrees and adduction by 4.3 degrees. Implanting larger diameter glenospheres increased external rotation and adduction by 9.4 and 10.1 degrees respectively. Glenosphere tilt had a negligible effect on impingement-free ROM. Maximizing inferior glenosphere eccentricity, lateralizing the glenosphere, and implanting larger glenosphere diameters improves impingement-free range of motion, in particular external rotation, of an onlay RSA prosthesis. Surgeons’ awareness of these trends can help optimize glenoid component position to maximise impingement-free ROM for RSA. Further studies are required to validate these findings in the context of scapulothoracic motion and soft tissue constraints

The primary goals of successful rTSA (Reverse Total Shoulder Arthroplasty) are pain relief, improved shoulder motion and function with the restoration of patient independence. These goals can be achieved by optimal prosthesis design and surgical technique. Historically there have been two predominant reverse shoulder design philosophies: the traditional valgus 155-degree neck-shaft angle with a medialised center of rotation introduced by Dr. Grammont, and the more recent varus 135-degree neck-shaft angle with a lateralised center of rotation, developed by Dr. Frankle. The latter design has reported lower incidences of scapular notching, coupled with improved adduction and external rotation. Over time, an understanding of the factors which resulted in clinical complications and those that contributed to the clinical success of both these design philosophies has been analyzed and widely publicised. With the currently available reverse prostheses the surgeon is required to be committed to one design philosophy or the other. This commitment to one singular design may hinder surgeons from the ability to individualise each case regardless of patient anatomy, rotator cuff condition, arthritic state and post-operative expectation. Recently, a system has been launched which offers both design philosophies in one system, providing unsurpassed intra-operative flexibility. This allows the surgeon to adapt to each individual case and choose either design philosophy based on patient condition and anatomy, thus optimizing patient outcome. The treatment of proximal humeral fractures has historically included Hemi Arthroplasty (HA) or Total Shoulder Arthroplasty (TSA). However, rTSA has recently become the surgery of choice for many fracture treatments based on more reproducible results. Certain implant characteristics are gaining favor in the treatment of proximal humerus fractures namely:. Press fit humeral stems - which avoid the risks of cement in-between the tuberosities which has been reported to compromise healing. Proximal ‘box-shape’ geometry - which enables rotational stability especially in cases with proximal bone loss to promote reconstruction leading to improved healing. 135-degree neck-shaft angle - allowing a higher and more anatomic tuberosity position for more stable fixation maintains anatomical integrity of the tuberosities which has been reported as a critical factor for retaining rotator cuff function

Objectives. The shape of proximal femur is important for the selection of implant in total hip arthroplasty (THA). There are few reports about the shape of proximal femur. We analyzed preoperative and postoperative conditions of the proximal femurs of patients before and after total hip arthroplasty with computed tomography (CT) and evaluated the compatibility to the cementless stem. Materials and Methods. We analyzed 65 hips of 63 patients (10 males and 53 females) who had THA between January 2008 and December 2010 in our hospital. We approximated the center of the femoral head as the center of the inscribed sphere in the femoral head. We defined the axis of proximal femur with the line between the centers of the circles located at 45 mm distal from lesser trochanter (LT) and at 90 mm proximal from LT. We measured the neck-shaft angle of femur, offset of femoral head, and diameter of bone-marrow cavity. After operation, we measured the distance between the stem surface and the edge of the femoral cortex (SF) at 10 mm proximal from LT to evaluate the compatibility of CT. We used PerFix HA cementless stem (Kyocera medical co., Osaka). Results. The mean diameter of femoral head was 46.1 mm, neck-shaft angle was 128.9 degrees, horizontal offset was 33.5 mm, and vertical offset was 41.6 mm. The mean diameters of bone-marrow cavity were 20.8 mm at 10 mm proximal level from LT, 14.2 mm at 20 mm distal level from LT and 9.9 mm at 100 mm distal level from LT. The medial shape was curved within 40 mm distal point from lesser trochanter. The mean of SF was 3.4 mm (0–5.1mm) and SF values of 43 hips were less than 2.0 mm. The mean of CFI was 3.6. Discussions and Conclusions. Several reports described about the shape of proximal femur on X-ray. However, it is inaccurate if we do not correct for the influence of anteversion angle of femur. For cementless stem, it is important to fit the medial area to the surface and the compatibility depends on the flare of the proximal femur

Background. Stemless prostheses are recognized to be an effective solution for anatomic total shoulder arthroplasty (TSA) while providing bone preservation and shortest operating time. Reverse shoulder arthroplasty (RSA) with stemless has not showed the same effectiveness, as clinical and biomechanical performances strongly depend on the design. The main concern is related to stability and bone response due to the changed biomechanical conditions; few studies have analyzed these effects in anatomic designs through Finite Element Analysis (FEA), however there is currently no study analyzing the reverse configuration. Additionally, most of the studies do not consider the effect of changing the neck-shaft angle (NSA) resection of the humerus nor the proper assignment of spatial bone properties to the bone models used in the simulations. The aim of this FEA study is to analyze bone response and primary stability of the SMR Stemless prosthesis in reverse with two different NSA cuts and two different reverse angled liners, in bone models with properties assigned using a quantitative computed tomography (QCT) methodology. Methods. Sixteen fresh-frozen cadaveric humeri were modelled using the QCT-based finite element methodology. The humeri were CT-scanned with a hydroxyapatite phantom to allow spatial bone properties assignment [Fig. 1]. Two implanted SMR stemless reverse configurations were considered for each humerus: a 150°-NSA cut with a 0° liner and a 135°-NSA cut with a 7° sloped liner [Fig. 2]. A 105° abduction loading condition was simulated on both the implanted reverse models and the intact (anatomic) humerus; load components were derived from previous dynamic biomechanical simulations on RSA implants for the implanted stemless models and from the OrthoLoad database for the intact humeri. The postoperative bone volume expected to resorb or remodel [Fig. 3a] in the implanted humeri were compared with their intact models in sixteen metaphyseal regions of interest (four 5-mm thick layers parallel to the resection and four anatomical quadrants) by means of a three-way repeated measures ANOVA followed by post hoc tests with Bonferroni correction. In order to evaluate primary stability, micromotions at the bone-Trabecular Titanium interface [Fig. 3b] were compared between the two configurations using a Wilcoxon matched-pairs signed-rank test. The significance level α was set to 0.05. Results. With the exception of the most proximal layer (0.0 – 5.0 mm), the 150°-NSA configuration showed overall a statistically significant lower bone volume expected to resorb (p = 0.011). In terms of bone remodelling, the 150°-NSA configuration had again a better response, but fewer statistically significant differences were found. Regarding micromotions, there was a median decrease (Mdn = 3.2 μm) for the 135°-NSA configuration (Mdn = 40.3 μm) with respect to the 150°-NSA configuration (Mdn = 43.5 μm) but this difference was non-significant (p = 0.464). Conclusions. For the analyzed SMR Stemless configurations, these results suggest a reduction in the risk of bone resorption when a 0° liner is implanted with the humerus cut at 150°. The used QCT-based methodology will allow further investigation, as this study was limited to one single design and load case. For any figures or tables, please contact the authors directly

Introduction. To control implant alignments (anteversion and abduction angle of the acetabular cup and antetorsion of the femoral stem) within an appropriate angle range is essentially important in total hip arthroplasty to avoid implant impingement. A navigation system is necessary for accurate intraoperative evaluation of implant alignments but is too expensive and time-consuming to be commonly used. Therefore, a cheaper and easier tool for intraoperative evaluation of the alignments is desired in the clinical field. I presented an idea of marking ruler-like scales on a trial femoral head in the last ISTA Congress. The purpose of this study is to introduce an idea further improved in evaluating the combined implant alignment intraoperatively. Materials and Methods. We can evaluate the combined anteversion (sum of cup anteversion and stem antetorsion) and cup abduction angle by reading the scales at the most proximal point of inner edge of the liner when horizontal and vertical scales are marked on the femoral head appropriately and the hip joint is kept at the neutral position after implant settings and trial reduction. Whether the impingement occurred within the target ROM (Flx 130, IR40@Flx90, Ext 40, ER 40) was judged under specific conditions of the oscillation angle (139), neck-shaft angle of the stem (130), stem adduction angle (7), stem antetorsion (20 or 30), and cup anteversion and abduction angles. Cup anteversion and abduction angles were changed from 0 to 40 and 30 to 50 degrees in 1-degree increments, respectively. Impingement judgment was performed mathematically for each combination of implant alignment based on matrix transformations and trigonometric formulas. Results. Impingement-free combinations of implant alignments were identified using spreadsheet software. Points which indicated impingement-free when they matched with the most proximal point of the inner edge of the liner when the hip joint was kept neutral were plotted on the surface of the head on a 3-dimensional computer graphic software. Thus, the safe zone could be indicated visually on the trial head by a collection of these points. Discussion. We can easily judge whether the implant impingement occurs or not by using this trial head intraoperatively. However, there are several factors which make the judgment inaccurate. First, the safe zone varies according to the stem antetorsion. Second, the position at which the hip is kept intraoperatively is not necessarily neutral. Third, stem adduction angle varies according to the length of the femur. Conclusion. Safe zone mapping on the trial femoral head is low cost and easy method to be introduced in the clinical practice for the purpose of a rough judgment of implant impingement

Introduction. In situ pinning for classic slipped capital femoral epiphysis(SLIP) is evolving to a more direct and anatomic realignment of proximal femoral epiphysis; but in no study the result of such a treatment in Valgus Slip, an uncommon type of slipped capital femoral epiphysis, has been reported. Material and methods. Three hips in three patients (one male, two female) with valgus SCFE were treated by sub-capital realignment (two hips) or femoral neck osteotomy (one hip) for anatomic realignment of proximal femoral epiphysis. Extended retinacular flap technique performed through surgical hip dislocation in all hips. They followed clinically by Merle d'Aubigne Scale and visual analog scale for pain and radiographically for AVN, recurrence of SLIP, chondrolysis and osteoarthritis. Result. The age of the patients was 10,11 and 18 years. In all hips the neck-shaft angle was increased.18 years old male had bilateral chronic valgus SLIP with severe retro tilt of the head over the neck and bilateral acetabular dysplasia.11 years old girl with an acute valgus SLIP also had bilateral acetabular dysplasia and in 10 years old girl only one hip presented with acute on chronic valgus SLIP. All had severe displacement. The mean preoperative epiphyseal shaft angle (ESA) of 107.5° (range 85–125°) was reduced to 60° (range 55–70°) postoperatively. mean Merle d'Aubigne Scale was 16 and radiographically complete union and good alignment achieved without any complication. Conclusion. Anatomical realignment of proximal femoral epiphysis in this small series of patient with valgus type SCFE had good to excellent results

Objectives. For patients with Developmental Dysplasia of the Hip (DDH) who progress to needing total joint arthroplasty it is important to understand the morphology of the femur when planning for and undertaking the surgery, as the surgery is often technically more challenging in patients with DDH on both the femoral and acetabular parts of the procedure. 1. The largest number of male DDH patients with degenerative joint disease previously assessed in a morphological study was 12. 2. In this computed tomography (CT) based morphological study we aimed to assess whether there were any differences in femoral morphology between male and female patients with developmental dysplasia undergoing total hip arthroplasty (THA) in a cohort of 49 male patients, matched to 49 female patients. Methods. This was a retrospective study of the pre-operative CT scans of all male patients with DDH who underwent THA at two hospitals in Japan between 2006–2017. Propensity score matching was used to match these patients with female patients in our database who had undergone THA during the same period, resulting in 49 male and 49 female patients being matched on age and Crowe classification. The femoral length, anteversion, neck-shaft angle, offset, canal-calcar ratio, canal flare index, lateral centre-edge angle, alpha angle and pelvic incidence were measured for each patient on their pre-operative CT scans. Results. Significant differences were found in femoral anteversion with a mean male anteversion of 22 ˚ (±14.2), compared to 30˚ (±15.5), in females (p=0.02, Confidence Interval (C.I.) 1.6 to 14.9, Figure 1), offset, with a mean male offset of 31 mm (±6.2), compared to 29 mm (±6.1) in females, (p=0.04, C.I: 0.2 to 4.8), and femoral length with a mean femoral length of 434 mm in males (±22.2), compared to 407 mm in females (±23.9), (p<0.001, C.I: 19.2 to 34.3, Figure 2). No significant differences between male and female patients were found for the other measurements. Discussion. This was the first study of this size assessing femoral morphology in male patients with DDH undergoing THA. Significant differences were found between male and female patients in femoral anteversion, length and offset. This should be taken into account when planning and performing THA in these patients. Based on the findings from this study, a more anteverted femoral neck can be expected at the time of surgery in a female patient with DDH undergoing total hip arthroplasty, compared to a male patient

Computer navigation is an attractive tool for use in total knee arthroplasty (TKA), as it is well known that alignment is important for the proper function of a total knee replacement. Malalignment of the prosthetic joint can lead to abnormal kinematics, unbalanced soft-tissues, and early loosening. Although there are no long term studies proving the clinical benefits of computer navigation in TKA, studies have shown that varus alignment of the tibial component is a risk factor for early loosening. A handheld, accelerometer based navigation unit for use in total knee replacement has recently become available to assist the surgeon in making the proximal tibial and distal femoral cuts. Studies have shown the accuracy to be comparable to large, console-based navigation units. Additionally, accuracy of cuts is superior to the use of traditional alignment guides, improving the percentage of cuts within 2 degrees of the desired alignment. Because the registration is based on the mechanical axis of the knee, anatomic variables such as femoral neck-shaft angle, femoral length, and presence of a tibial bow do not affect the results. The handheld aspect of this navigation unit allows its use without additional incisions or array attachment. Furthermore, the learning curve and usage time is minimal, supporting its use in primary TKA

Introduction. Limb length discrepancy after THA can result in medicolegal litigation. It can create discomfort for the patient and potentially cause back pain or affect the longevity of the implant. Some patients tolerate the length inequality better compared to others despite difference in anatomical femoral length after surgery. Methods and materials. We analyzed the 3D EOS images of 75 consecutive patients who underwent primary unilateral THA (27 men, 48 women). We measured the 3D length of the femur and tibia (anatomical length), the 3D global anatomical length (the sum of femur and tibia anatomical lengths), the 3D functional length (center of the femoral head to center of the ankle), femoral neck-shaft angle, hip-knee-ankle angle, knee flexum/recurvatum angle, sacral slopes and pelvic incidence. We correlated these parameters with the patient perception of the leg length. Results. The values for leg length and pelvic parameters are shown in table 1. 37 patients had a perception of the LLD (49.3%). When the global anatomical length was shorter on the operated side, the perception of the discrepancy was observed in 56% of the cases. In case of anatomical length longer on the operated side, the perception of the discrepancy was described by the patients in 46% of the cases. The LLD perception was correlated with difference in functional length (p=0.0001), pelvic obliquity (p=0.003) and sacral slope (p=0.023). The anatomical femoral length was not correlated with the LLD perception (p=0,008). Discussion. The perception of LLD is a multifactorial complication. We found that the anatomical femoral length (that can be directly affected by the position of the stem) is not the only important factor. The functional length of the lower extremity which can also be affected by the knee deformities is better correlated with the LLD. The pelvic obliquity and version also affect the patient perception of the LLD

Computer navigation is an attractive tool for use in total knee arthroplasty (TKA), as it is well known that alignment is important for the proper function of a total knee replacement. Malalignment of the prosthetic joint can lead to abnormal kinematics, unbalanced soft-tissues, and early loosening. Although there are no long term studies proving the clinical benefits of computer navigation in TKA, studies have shown that varus alignment of the tibial component is a risk factor for early loosening. A handheld, accelerometer based navigation unit for use in total knee replacement has recently become available to assist the surgeon in making the proximal tibial and distal femoral cuts. Studies have shown the accuracy to be comparable to large, console-based navigation units. Additionally, accuracy of cuts is superior to the use of traditional alignment guides, improving the percentage of cuts within 2 degrees of the desired alignment. Because the registration is based on the mechanical axis of the knee, anatomic variables such as femoral neck-shaft angle, femoral length, and presence of a tibial bow do not affect the results. The handheld aspect of this navigation unit allows its use without additional incisions or array attachment. Furthermore, the learning curve and usage time is minimal, supporting its use in primary TKA

Introduction. Although total hip arthroplasty is a very successful operation, complications such as: dislocation, aseptic loosening, and periprosthetic fracture do occur. These aspects have been studied in large populations for traditional stem designs, but not for more recent short stems. The design rationale of short stems is to preserve bone stock, without compromising stability. However, due to their smaller bone contact area, high peak stresses and areas of stress shielding could appear in the proximal femur, especially in the presence of atypical bone geometries. In order to evaluate this aspect, we quantified the stress distribution in atypical proximal femurs implanted with a commercially available calcar guided short stem. Methods. Geometrical shape variations in neck-shaft angle (NSA), neck-length (NL) and anteversion (AV), were determined three-dimensionally in the Mimics Innovation Suite (Materialise N.V., Leuven, Belgium) from a CT dataset of 96 segmented femurs. For each shape variation, the femurs that had the two lowest, two average and two highest values were included (18 femurs). Using scripting functionality in Mimics, CAD design files of the calcar guided Optimys short stem (Mathys, Bettlach, Switzerland) were automatically sized and aligned to restore the anatomical hip rotation center. Stem size and position were manually corrected by an orthopedic surgeon before finite element (FE) models were constructed using a non-manifold assembly approach (Figure 1). Material properties were estimated from the CT dataset and loads representing walking and stair climbing were applied [1]. Stress-shielding was evaluated by the change in average strain energy density pre- and post-operatively in three different regions (calcar, midstem, tip) each being subdivided in four quarters (medial, lateral, anterior, posterior) (Figure 2). Results. Stress shielding in the proximal femur was seen in all models, especially in the calcar-medial region. In that region, the largest variation in stress shielding was observed for the models with an atypical NSA, ranging from 57% to 96%. The lowest amount was found in a patient with an average NSA (124°), and the highest amount was found in a patient with a small NSA (109°) (Figure 2). In the models selected for their varying neck lengths, calcar-medial stress shielding increased from 69% (NL 53 mm) to 97% (NL 66 mm). Stress shielding was least sensitive to variations in AV, ranging from 79% to 92%. Similar patterns were observed for walking and stair climbing loads. Discussion. Stress shielding was smallest in femurs where the load-transfer between implant and bone was located more proximally, while higher levels of stress shielding occurred when the load transfer was more pronounced at the tip of the stem (Figure 3). Two femurs with an average NSA and NL showed substantially lower stress shielding than the 16 other femurs. This may suggest that the calcar guided Optimys short stem prevents stress shielding especially in average femurs, but less so in atypical femurs. Hence, a larger study population should be investigated to support this hypothesis. For any figures or tables, please contact the authors directly

Computer navigation is an attractive tool for use in total knee arthroplasty (TKA), as it is well known that alignment is important for the proper function of a total knee replacement. Malalignment of the prosthetic joint can lead to abnormal kinematics, unbalanced soft tissues, and early loosening. Although there are no long term studies proving the clinical benefits of computer navigation in TKA, studies have shown that varus alignment of the tibial component is a risk factor for early loosening. A handheld, accelerometer-based navigation unit for use in total knee replacement has recently become available to assist the surgeon in making the proximal tibial and distal femoral cuts. Studies have shown the accuracy to be comparable to large, console-based navigation units. Additionally, accuracy of cuts is superior to the use of traditional alignment guides, improving the percentage of cuts within 2 degrees of the desired alignment. Because the registration is based on the mechanical axis of the knee, anatomic variables such as femoral neck-shaft angle, femoral length, and presence of a tibial bow do not affect the results. The handheld aspect of this navigation unit allows its use without additional incisions or array attachment. Furthermore, the learning curve and usage time is minimal, supporting its use in primary TKA

Computer navigation is an attractive tool for use in total knee arthroplasty (TKA), as it is well known that alignment can affect clinical results. Malalignment of the prosthetic joint can lead to abnormal kinematics, unbalanced soft-tissue, and early loosening. Although there are no long term studies proving the clinical benefits of computer navigation in TKA, studies have shown that varus alignment of the tibial component is a risk factor for early loosening. A handheld, accerelerometer based navigation unit for use in total knee replacement has recently become available to assist the proximal tibial and distal femoral cuts. Studies have shown the accuracy to be comparable to large, console-based navigation units. Additionally, accuracy of cuts is superior to the use of traditional alignment guides, improving the percentage of cuts within 2 degrees of the desired alignment. Because the registration is based on the mechanical axis of the knee, anatomic variables such as femoral neck-shaft angle, femoral length, and presence of a tibial bow do not affect the results. The handheld aspect of this navigation unit allows its use without additional incisions or array attachment. Furthermore, the learning curve and usage time is minimal, supporting its use in primary TKA