Aims. Complex total hip arthroplasty (THA) with subtrochanteric shortening osteotomy is necessary in conditions other than developmental dysplasia of the hip (DDH) and septic arthritis sequelae with significant proximal femur migration. Our aim was to evaluate the hip centre restoration with THAs in these hips. Methods. In all, 27 THAs in 25 patients requiring THA with femoral shortening between 2012 and 2019 were assessed. Bilateral shortening was required in two patients. Subtrochanteric shortening was required in 14 out of 27 hips (51.9%) with aetiology other than DDH or septic arthritis. Vertical centre of rotation (VCOR), horizontal centre of rotation, offset, and functional outcome was calculated. The mean followup was 24.4 months (5 to 92 months). Results. The mean VCOR was 17.43 mm (9.5 to 27 mm) and horizontal centre of rotation (HCOR) was 24.79 mm (17.2 to 37.6 mm). Dislocation at three months following acetabulum reconstruction required femoral shortening for offset correction and hip centre restoration in one hip. Mean horizontal offset was 39.72 (32.7 to 48.2 mm) compared to 42.89 (26.7 to 50.6 mm) on the normal side. Mean Harris Hip Score (HHS) of 22.64 (14 to 35) improved to 79.43 (68 to 92). Mean pre-operative shortening was 3.95 cm (2 to 8 cm). Residual limb length discrepancy was 1.5 cm (0 to 2 cm). Sciatic neuropraxia in two patients recovered by six months, and femoral neuropraxia in one hip recovered by 12 months. Mean Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was 13.92 (9 to 19). Mean 12-item short form survey (SF-12) physical scores of 50.6 and mental of 60.12 were obtained. Conclusion. THA with subtrochanteric shortening is valuable in complex hips with high dislocation. The restoration of the hip centre of rotation and offset is important in these hips. Level of evidence IV. Femoral shortening useful in conditions other than DDH and septic sequelae. Restoration of hip centre combined with offset to be planned and ensured

Aims. Hip arthroplasty aims to accurately recreate joint biomechanics. Considerable attention has been paid to vertical and horizontal offset, but femoral head centre in the anteroposterior (AP) plane has received little attention. This study investigates the accuracy of restoration of joint centre of rotation in the AP plane. Methods. Postoperative CT scans of 40 patients who underwent unilateral uncemented total hip arthroplasty were analyzed. Anteroposterior offset (APO) and femoral anteversion were measured on both the operated and non-operated sides. Sagittal tilt of the femoral stem was also measured. APO measured on axial slices was defined as the perpendicular distance between a line drawn from the anterior most point of the proximal femur (anterior reference line) to the centre of the femoral head. The anterior reference line was made parallel to the posterior condylar axis of the knee to correct for rotation. Results. Overall, 26/40 hips had a centre of rotation displaced posteriorly compared to the contralateral hip, increasing to 33/40 once corrected for sagittal tilt, with a mean posterior displacement of 7 mm. Linear regression analysis indicated that stem anteversion needed to be increased by 10.8° to recreate the head centre in the AP plane. Merely matching the native version would result in a 12 mm posterior displacement. Conclusion. This study demonstrates the significant incidence of posterior displacement of the head centre in uncemented hip arthroplasty. Effects of such displacement include a reduction in impingement free range of motion, potential alterations in muscle force vectors and lever arms, and impaired proprioception due to muscle fibre reorientation. Cite this article: Bone Joint Res 2022;11(3):180–188

Aims. With resumption of elective spine surgery services in the UK following the first wave of the COVID-19 pandemic, we conducted a multicentre British Association of Spine Surgeons (BASS) collaborative study to examine the complications and deaths due to COVID-19 at the recovery phase of the pandemic. The aim was to analyze the safety of elective spinal surgery during the pandemic. Methods. A prospective observational study was conducted from eight spinal centres for the first month of operating following restoration of elective spine surgery in each individual unit. Primary outcome measure was the 30-day postoperative COVID-19 infection rate. Secondary outcomes analyzed were the 30-day mortality rate, surgical adverse events, medical complications, and length of inpatient stay. Results. In all, 257 patients (128 males) with a median age of 54 years (2 to 88) formed the study cohort. The mean number of procedures performed from each unit was 32 (16 to 101), with 118 procedures (46%) done as category three prioritization level. The majority of patients (87%) were low-medium “risk stratification” category and the mean length of hospital stay was 5.2 days. None of the patients were diagnosed with COVID-19 infection, nor was there any mortality related to COVID-19 during the 30-day follow-up period, with 25 patients (10%) having been tested for symptoms. Overall, 32 patients (12%) developed a total of 34 complications, with the majority (19/34) being grade 1 to 2 Clavien-Dindo classification of surgical complications. No patient required postoperative care in an intensive care setting for any unexpected complication. Conclusion. This study shows that safe and effective planned spinal surgical services can be restored avoiding viral transmission, with diligent adherence to national guidelines and COVID-19-secure pathways tailored according to the resources of the individual spinal units. Cite this article: Bone Jt Open 2021;2(12):1096–1101

Abstract. Introduction. The incidence of significant acute chondral injuries with patella dislocation is around 10–15%. It is accepted that chondral procedures should only be performed in the presence of joint stability. Methodology. Patients were identified from surgeon/hospital logs. Patient demographics, lesion size and location, surgical procedure, patient reported outcome measures, post-operative MR imaging and complications were recorded. PROMs and patient satisfaction was obtained. Results. 20 knees (18 patients) were included. Mean age was 18.6 years (range; 11–39) and the mean follow-up was 16.6 months (range; 2–70). The defect locations were the lateral femoral condyle (9/20; 45%), patella (9/20; 45%), medial femoral condyle (1/20; 5%) and the trochlea (1/20; 5%). The mean defect size was 2.6cm2. Twelve knees were treated with cartilage fixation, 5 with microfracture and 3 with OATS. At follow up, the overall mean Lysholm score was 77.4 (± 17.1) with no chondral regenerative procedure being statistically superior. There was no difference in Lysholm scores between those patients having acute medial patellofemoral ligament reconstruction versus medial soft tissue plication (p=0.59). Five (25%) knees required re-operation (one arthroscopic arthrolysis; one patella chondroplasty; two removal of loose bodies; one implant adjustment). Overall 90% responded as being satisfied with surgery. Conclusion. Our aggressive pathway to identify and treat acute cartilage defects with early operative intervention and patella stabilisation has shown high rates of satisfaction and Lysholm scores with no major revisions. The full range of chondral restoration options should be considered by surgeons managing these patients

Introduction. The objective of our study was to determine the extent to which the quality of the biomechanical reconstruction when performing hip replacement influences gait performances. We aimed to answer the following questions: 1) Does the quality of restoration of hip biomechanics after conventional THR influence gait outcomes? (question 1), and 2) Is HR more beneficial to gait outcomes when compared with THR? (question 2). Methods. we retrospectively reviewed 52 satisfied unilateral prosthetic hip patients (40 THRs and 12 HRs) who undertook objective gait assessment at a mean follow-up of 14 months. The quality of the prosthetic hip biomechanical restoration was assessed on standing pelvic radiograph by comparison to the healthy contralateral hip. Results. We were unable to detect any statistically significant correlation between the radiographical parameters and the gait data, for THR patients. In stress conditions (inclination or declination of the ramp), the gait was more symmetric in the HR group, compared to the THR group. Discussion/Conclusions. We found that slight variations in the quality of the hip biomechanical restoration had little effect on gait outcomes of THR patients, and HR generated a more physiological gait under stress conditions than well-functioning THR

Background. Postoperative dislocation is one of the main surgical complications and the primary cause for revision surgery after 2-stage implant exchange due to periprosthetic infection of a total hip arthroplasty. Objective. The aims of our study were (1) to determine the incidence of dislocation after two-stage THA reimplantation without spacer placement, (2) to evaluate relevant risk factors for dislocation and (3) to assess the final functional outcome of those patients. Method. We prospectively analyzed 187 patients who underwent a two-stage total hip arthroplasty (THA) revision after being diagnosed with periprosthetic joint infection (PJI) from 2013 to 2019. The mean duration of follow-up was 54.2 ± 24.9 months (>36 months). The incidence of postoperative dislocation and subsequent revision was estimated through Kaplan-Meier curves and potential risk factors were identified using Cox hazard regression. The functional outcome of the patients was assessed using the modified Harris Hip Score (mHHS). Results. The estimated cumulative dislocation-free survival was 87.2% (95% CI: 81.2%-91.3%) with an estimated 10% and 12% risk for dislocation within the first 6 and 12 months, respectively. The use of a dual-mobility construct had no significant impact on the dislocation rate. Increasing body mass index (BMI) (HR=1.11, 95% CI: 1.02-1.19, p=0.011), abductor mechanism impairment (HR=2.85, 95% CI: 1.01-8.01, p=0.047), the extent of elongation of the affected extremity between stages (HR=1.04, 95% CI: 1.01-1.07, p=0.017), the final leg length discrepancy (HR=1.04, 95% CI: 1.01-1.08, p=0.018) and PJI recurrence (HR=2.76, 95% CI: 1.00-7.62, p=0.049) were found to be significant risk factors for dislocation. Overall revision rates were 17% after THA reimplantation. Dislocated hips were 62% more likely to undergo re-revision surgery (p<0.001, Log-rank= 78.05). A significant average increase of 30 points in mHHS scores after second-stage reimplantation (p=0.001, Wilcoxon-rank) was recorded, but no difference was noted in the final HHS measurements between stable and dislocated hips. Conclusion. Dislocation rates after 2-stage THA reimplantation for PJI remain high, especially regarding overweight or re-infected patients. Careful leg length restoration and an intact abductor mechanism seem critical to ensure stability in these complex patients

Restoration of anatomy is paramount in total hip arthroplasty (THA) to optimise function and stability. Leg-length discrepancy of ≥10mm is poorly tolerated and can be the subject of litigation. We routinely use a multimodal protocol to optimise soft tissue balancing which involves pre-operative templating, leg-length measurement supine and in the lateral position after positioning, and the use of an intra-operative leg-length measurement device to ensure optimisation of leg-length. We have analysed the results of our protocol in restoring leg-length in primary THA. Radiological leg-length was measured in a consecutive series of 50 patients who had THA for unilateral arthritis by an independent observer pre- and post-operatively using validated methods utilising radiological software. The measurements pre- and post-operative were compared. Patients with bilateral hip arthritis and poor imaging were excluded. Leg-length was successfully restored to within 5.0mm of the target leg-length in 84.0% of patients (mean +0.7mm (95% CI +0.2 to +1.1)). The other 14.0% of patients were restored to within 5.1–8.0mm (mean +2.2mm (95% CI −2.7 to +7.1)) and 2.0% of patients were restored to within 8.1–10.0mm. Leg length was accurately restored across the subset of patients within a narrow range of either side of the mean target leg length. Intra-operative measurement of leg length can be difficult but is vital in ensuring appropriate restoration of leg-length. We recommend a similar multimodal protocol to ensure restoration of leg-length within narrow limits to maximise function and patient satisfaction

INTRODUCTION. The restoration of the anatomical hip rotation center (HRC) has a major influence on the longevity of hip prostheses. Deviations from the HRC of the anatomical joint after total hip arthroplasty (THA) can lead to increased hip joint forces, early wear or loosening of the implant. The contact conditions of acetabular press-fit cups after implantation, including the degree of press-fit, the existence of a polar gap and cup orientation, may affect the HRC restoration, and therefore implant stability. The aim of this study was to determine the influence of acetabular press-fit, polar gap and cup orientation on HRC restoration during THA. METHODS. THAs were performed by an experienced orthopaedic surgeon in full cadaveric models simulating real patient surgery (n=7). Acetabular cups with a Porocoat™ (n=3) and Gription™ surface coating (n=4) were implanted (DePuy Synthes, Leeds, UK). Computed tomography (CT) scans prior to surgery, as well as after reaming and implantation of press-fit cups were used to calculate the HRC displacement. After aligning the pelves in the anterior pelvic plane, 3D reconstruction of the HRC at each stage was performed by fitting spheres to the femoral head, the reamed cavity and the inserted cup. 3D surface models of the cups were generated using a laser scanner and were registered to the CT images. The effective press-fit was calculated using the diameters of spheres, fitted to the cavity prior to cup insertion and to the outer cup coating. The polar gap was defined as the difference between the outer cup surface and the subchondral bone at the cup pole. Anteversion and abduction angles were calculated as difference between the cup planes and the sagittal and transverse plane, respectively. RESULTS. A medial (6.4±1.6mm), superior (5.1±1.5mm) and posterior (3.0±1.4mm) displacement of the HRC after reaming was measured. A significant inferior shift of the HRC could be measured after cup implantation (p=0.043). No significant influence of the coating design on the HRC shift could be observed. The shift of the HRC back towards the anatomical HRC was highly correlated to the degree of polar gap (R. 2. =0.928, p<0.001) and a trend towards an association with effective press-fit was observed (R. 2. =0.536, p=0.061). The cup angles had no influence on the shift of the HRC, but a high variability in cup anteversion (20.7° to 61.8°) was observed. DISCUSSION. The study suggests that increasing the press-fit and polar gap improves the restoration of the anatomical HRC. Since increasing the degree of press-fit could also lead to higher stresses and an increased fracture risk, future work will study how the acetabular contact conditions influence both primary implant stability and fracture risk, in order to establish an optimal HRC reconstruction to maximize implant longevity

Proper restoration of posterior condylar offset during TKA has been shown to be important to maximize range of motion and minimize flexion instability. However, there is little information as to the importance of restoration of mid-sagittal femoral geometry. There is controversy as to whether a TKA prosthesis should have a single radius or multiple radii of curvature. The purpose of this study is to evaluate the effectiveness of a multi-radius femoral component at restoring mid sagittal femoral offset. A consecutive series of 100 TKAs with digital preoperative and postoperative radiographs and standardized radiographic markers were analyzed. There were 71 female and 29 male knees with mean age of 59 years. All TKAs were performed by a single surgeon using a multi-radius femoral component design. The distal femoral resection was set to resect 10 mm from the distal femoral condyle and a posterior referencing system was used to size the femoral component. Using radiographic perfect lateral projections of the knees, a line was drawn along the posterior femoral shaft and another parallel line down the anterior femoral shaft. A 3rd line was then drawn parallel to the posterior shaft at the furthest point posterior on the condyle. A 4th line was drawn parallel to the anterior shaft at the furthest point anterior on the femur. 90 degree angles were constructed to create a grid in the anterior and posterior directions, similar to a previously reported technique. Finally, 45 degree angle lines were created in the grid to assess mid flexion dimensions [Fig-1 and 2]. The percent change in posterior condylar offset (PCO), anterior femoral offset (AFO), mid femoral anterior offset (MAFO) and mid femoral posterior offset (MFPO) were calculated. The mean reproduction of the mid-anterior femoral offset and mid-posterior femoral offset were 101.1% [range 56.5%–167.5%] and 96.8% [range 54.9%–149.0%] of preoperative measurements respectively. The average restoration of posterior offset and anterior offset were 92.8% [range 49.0%–129.8%] and 115.3% of preoperative measurements [range 35.7%–400.0%] respectively. When the posterior condylar offset was restored to within 10% of the native anatomy, the MPFO restoration more closely resembled normal anatomy (103.0% vs. 93.9%, p = 0.005). When the postoperative posterior condylar offset was decreased greater than 20%, both the MAFO (90.1% vs. 104.5%, p = 0.004) and MPFO (78.5% vs. 102.9%, p < 0.001) decreased compared to the native knee. There was no relationship between restoration of the PCO and the MAFO correction (104.6% vs. 99.4%, p = 0.213). Finally, there was no correlation between restoration of anterior femoral offset within 10% of normal and the restoration of mid sagittal femoral offset; 98.0% vs 102.0% for MAFO (p = 0.320) and 98.7% vs 96.3% for MPFO (p = 0.569). A modern multi-radius condylar knee design is capable of reproducing the mid-sagittal geometry of the preoperative knee. However, the restoration of mid sagittal offset is largely dependent on the restoration of the posterior condylar offset. Intraoperative adjustments in anterior and posterior femoral resections can have significant impact in the ability of the implant to reproduce mid-sagittal femoral anatomy

Despite worldwide clinical use of bio-absorbable devices for internal fixation in orthopaedic surgery, the degradation behaviour and tissue replacement of these implants are not fully understood. In a long-term experimental study, we have determined the patterns of tissue restoration 36 and 54 months after implantation of polyglycolic acid and poly-laevo-lactic acid screws in the distal femur of the rabbit. After 36 months in the polyglycolic acid group the specimens showed no remaining polymer and loose connective tissue occupied 80% of the screw track. Tissue restoration remained poor at 54 months, the amounts of trabecular bone and haematopoietic elements being significantly lower than those in the intact control group. The amount of trabecular bone within the screw track at 54 months in the polyglycolic acid group was less than in the empty drill holes (p = 0.04). In the poly-laevo-lactic acid group, polymeric material was present in abundance after 54 months, occupying 60% of the cross-section of the core area of the screw track. When using absorbable internal fixation implants we should recognise that the degradation of the devices will probably not be accompanied by the restoration of normal trabecular bone

Purpose: Endoprosthetic reconstruction of the distal femur is the preferred approach for patients undergoing resection of bone sarcomas. The traditional How-medica Modular Resection System, using a press-fit stem (HMRS or Kotz prosthesis, Stryker Orthopaedics, Mahwah, New Jersey, USA) has shown good long-term clinical success, but has also been known to incur complications such as stem fracture. The Restoration stem, as a part of the new Global Modular Resection System (GMRS, Stryker Orthopaedics, Mahwah, NJ, USA), is currently proposed for this same application. This stem has a different geometry and provides the advantage of decreased risk of fracture of the component. The goal of this study was to compare the HMRS and Restoration press-fit stems in terms of initial mechanical stability. Methods: Six matching pairs fresh frozen adult femora were obtained and prepared using a flexible canal reamer and fitted with either a Restoration or HMRS press-fit stem distally. All constructs were mechanically tested in axial compression, lateral bending, and torsion to obtain mechanical stiffness. Torque-to-failure was finally performed to determine the offset force required to clinically fail the specimen by either incurring damage to the femur, the stem, or the femur-stem interface. Results: Restoration press-fit stems results were: axial stiffness (average=1871.1 N/mm, SD=431.2), lateral stiffness (average=508.0 N/mm, SD=179.6), and torsional stiffness (average=262.3 N/mm, SD=53.2). HMRS stems achieved comparable levels: axial stiffness (average=1867.9 N/mm, SD=392.0), lateral bending stiffness (average=468.5 N/mm, SD=115.3), and torsional stiffness (average=234.9 N/mm, SD=62.4). For torque-to-failure, the applied offset forces on Restoration (average=876.3 N, SD=449.6) and HMRS (aver-age=690.5 N, SD=142.0) stems were similar. There were no statistical differences in performance between the two stem types regarding axial compression (p=0.97), lateral bending (p=0.45), or torsional stiffnesses (p=0.07). Moreover, no differences were detected between the groups when tested in torque-to-failure (p=0.37). The mechanism of torsional failure for all specimens was “spinning” (i.e. surface sliding) at the femur-stem interface. No significant damage was detected to any bones or stem devices. Conclusions: These results suggest that the Restoration and HMRS press-fit stems may be equivalent clinically in the immediate post-operative situation. Funding: Commerical funding Funding Parties: Stryker Orthopaedics

Abstract. Objective. Radial to axillary nerve and spinal accessory (XI) to suprascapular nerve (SSN) transfers are standard procedures to restore function after C5 brachial plexus dysfunction. The anterior approach to the SSN may miss concomitant pathology at the suprascapular notch and sacrifices lateral trapezius function, resulting in poor restoration of shoulder external rotation. A posterior approach allows decompression and visualisation of the SSN at the notch and distal coaptation of the medial XI branch. The medial triceps has a double fascicle structure that may be coapted to both the anterior and posterior division of the axillary nerve, whilst preserving the stabilising effect of the long head of triceps at the glenohumeral joint. Reinnervation of two shoulder abductors and two external rotators may confer advantages over previous approaches with improved external rotation range of motion and strength. Methods. Review of the clinical outcomes of 22 patients who underwent a double nerve transfer from XI and radial nerves. Motor strength was evaluated using the MRC scale and grade 4 was defined as the threshold for success. Results. 18/22 patients had adequate follow-up (Mean: 29.5 months). Of these, 72.2% achieved ≥grade 4 power of shoulder abduction and a mean range of motion of 103°. 64.7% achieved ≥grade 4 external rotation with a mean range of motion of 99.6°. Conclusions. The results suggest the use of the combined nerve transfer for restoration of shoulder function via a posterior approach, involving the medial head branch of triceps to the axillary nerve and the XI to SSN

Aim: The Low Contact Stress (LCS) Total Knee Replacements (TKR) is a well-established mobile bearing prosthesis with more than 25 year experience, while the Kinemax Plus is a well established fixed bearing prosthesis. We examined whether reproducing the joint line height to within 5 mm of the pre-operative joint line height had any impact on the clinical outcome in the two different types of Total Knee Replacements. Method: 48 consecutive LCS knee replacements with a minimum of 2 years follow up had their pre and postoperative joint line (using Figgie’s method) and range of movement (ROM) measured. We used the Oxford Knee Score as a clinical outcome measurement tool. A cohort group of 53 CR Kinemax plus TKR from the Bristol Knee group was matched for age and sex. They had the same parameters measured. Results: Accurate joint line restoration was achieved significantly more frequently (P< 0.05) in the Kinemax group. Better post-operative ROM also occurred in the Kinemax group than the LCS, p = 0.03 and the former produced a bigger gain in ROM p < 0.01. However, no difference in the Oxford Knee Score existed between the two prostheses, p = 0.28. Joint line: elevation K+ LCS. 0–2 mm (16/48) = 33% (26/53) = 49% 2–5 mm (14/48) = 29% (14/53) = 26%> 5 mm (18/48) = 38% (12/53) = 25%. There was no significant difference in the ROM or Oxford Knee Score when the joint line was not elevated versus elevated for each prosthesis. However, there was suggestion that the ROM in LCS might be more sensitive to joint line changes, although this was not significant. ROM. K+ LCS. Normal joint line 116° 105°. Elevated joint line 108° 101°. Conclusion: Accurate joint line restoration could not be shown to correlate with either improved ROM or Oxford knee score; probably because of the small mount of elevation encountered and the small study size. There was a significantly greater post-operative increase in ROM with the Kinemax Plus relative to the LCS, and a significantly closer restoration of the joint line with the Kinemax Plus, both with respect to the actual measurement and with respect to the proportion of cases in which the joint line was accurately reproduced. This is surprising since in most K+ cases additional distal femur had been resected to avoid a tight knee. While in the LCS group special efforts had been made to achieve accurate restoration of the joint level

Abstract. Aim. With resumption of elective spine surgery services following the first wave of COVID-19 pandemic, we conducted a multi-centre BASS collaborative study to examine the clinical outcomes of surgeries. Methods. Prospective data was collected from eight spinal centres in the first month of operating following restoration of elective spine surgery following the first wave. Primary outcomes measures were the 30-day mortality rate and postoperative Covid-19 infection rate. Secondary outcomes analysed were the surgical, medical adverse events and length of inpatient stay. Results. 257 patients (128 Male) with an age range of 2–88 years formed the study cohort. The average workload from each unit was 32(range 16–101) with 118 procedures (46%) done as category 3 prioritisation level (Procedures performed in < 3 month). 87% of patients were low-medium “risk stratification” category. 195 patients (75.8%) isolated for two weeks preoperatively and all but four patients had COVID-19 negative test prior to surgery. None of the patients were diagnosed with COVID-19 infection nor was any mortality related to COVID-19 in the 30 day follow up period, with 25 patients having been tested for symptoms. 32 patients (12%) developed a total of 34 complications with 19/34 being grade 1–2 Clavien-Dindo classification of surgical complications. Median LOS 5.2 days and 78.4 % patients stayed less than a week. Conclusions. As per our study safe and effective planned spinal surgical services can be restored avoiding viral transmission, with adherence to national guidelines and COVID-secure pathways tailored according to the resources of the individual spinal units

Purpose. The positon of short stem is affected by the native anatomy of femoral neck and also by fixation mechanism dependent on design. As a consequence, it has been speculated that restoration of hip geometry might be limited in total hip arthroplasty (THA) using short stem. Therefore, the present study assessed the predictability of restoration of hip geometry using two different CCD-angled short stem engaging the lateral cortex. Materials and Methods. The 60 patients included 15 females and 45 males. The average age was 48.0 years with average BMI 24.2. Biomechanical parameters of hip geometry were analysed on postoperative calibrated radiographs in 30 consecutive primary unilateral THAs using short stem (Metha®, B. Braun Aesculap, Tuttlingen, Germany) with 120° CCD angle (group I) and 30 match controlled cases with 135° CCD angle (group II) and compared to those of the contralateral hip without deformity. The matching process was done before collecting the radiographic measurements by two blinded observer and was for sex, age ± 5 years, and BMI ± 7 units in that order. Results. Head length was short in 40%, 67%, medium in 37%, 23% and large in 23%, 10% of the patients in each group respectively with no significant difference in between group (p=0.11). The discrepancies of horizontal hip center of rotation (△HHCR) and the vertical hip center of rotation (△VHCR) compared to the contralateral side was similar in both groups (p=0.95, p= 0.11, respectively), which enabled to make a direct comparison of the femoral reconstruction. Compared to the contralateral side, discrepancies of limb length (△LLD) showed a borderline significant difference between two groups (avr.+0.7mm, +2.5mm respectively, p=0.04) with higher values for group of 135° CCD angle (more than 5mm of LLD in 27%). However, in group of 120° CCD angle, the discrepancies of horizontal femoral offset (△HFO) and abductor lever arm (△AbLA) (avr. +5.9 mm, +4.9mm respectively) revealed significantly increased compared with balanced value of group 135° CCD angle (+0.9mm, p <0.0001, +1.3mm, p=0.02, respectively) and about half of patients in group of 120° CCD angle revealed outside the 5mm difference target in either horizontal femoral offset (53% of patient) and abductor lever arm (50% of patient). Conclusion. With decreasing CCD-angle of short stem, restoration of limb length appears more predictable but, horizontal femoral offset and abductor lever arm increased with outside of a beneficial range. This tendency should be taken into consideration when choice the design of this kind of neck-preserving short stem as well as exact implantation technique

Alendronate is a potent inhibitor of bone resorptive activity, and has been shown to prevent and restore periprosthetic osteolysis in experimental models. A preliminary study was conducted to examine clinical usefulness of a lendronate treatment. Twenty-five patients (27 hips) with radiological evidence of osteolysis after cemented total hip arthroplasty were included. Of these, 14 patients (15 hips) were administered 5 mg of alendronate daily (alendronate group), and 11 patients (12 hips) did not receive alendronate treatment (control group). The subjects were followed up for 12 months, using radiological examinations and biochemical markers. The radiological analysis was evaluated blindly by 2 joint arthroplasty experts, each with more than 10 years of experience, without knowledge of alendronate administration. In the alendronate group, average serum bone alkaline phosphatase and urinary excretion of the N-telopep-tide of type I collagen values decreased from the baseline values after administration of alendronate, to 71% and 76% of baseline at the 3-month examination, and 57% and 62% at the 1-year examination, respectively. In the control group, expansion of osteolysis was found in 5 hips (42%) and no hip showed restoration of osteolysis. In the alendronate group, expansion of osteolysiswas found in 2 hips (13%), and restoration of osteolysis was found in 5 hips (33%). There was a statistically significant difference in ratio of hips with osteolysis restoration between the 2 groups (p< 0.05). In the alendronate group, there was no significant difference in age, average linear wear rate of polyethylene, and the biochemical markers, between the hips with and without diminishment of osteolysis. Conclusions: The present results indicate that clinicala-lendronate treatment can prevent and restore periprosthetic osteolysis, which is generally thought to require surgical intervention. These findings warrant further study of the effects of duration and dose of alendronate treatment, component materials, and component fixation methods

Today controversy exists whether restoration of neutral mechanical alignment should be attempted in all patients undergoing TKA. The restoration of constitutional rather than neutral mechanical alignment may in theory lead to a more physiological strain pattern in the collateral ligaments, and could therefore potentially be beneficial to patients. It was therefore our purpose to measure collateral ligament strains during three motor tasks in the native knee and compare them with the strains noted after TKA in different postoperative alignment conditions. Six cadaver specimens were examined using a validated knee kinematics rig under physiological loading conditions. The effect of coronal malalignment was evaluated by using custom made tibial implant inserts in order to induce different alignment conditions. The results indicated that after TKA insertion the strains in the collateral ligaments resembled best the preoperative pattern of the native knee specimens when constitutional alignment was restored. Restoration to neutral mechanical alignment was associated with greater collateral strain deviations from the native knee. Based upon this study, we conclude that restoration of constitutional alignment during TKA leads to more physiological periarticular soft tissue strains during loaded as well as unloaded motor tasks

Purpose: Total knee arthroplasty (TKA) is safe and effective in patients with advanced hemophilic arthropathy. This procedure is extremely successful in pain relief and improving functional status, however the limited restoration in motion due to preexisting soft tissue contractures, remains a concern. The purpose of this study is to report the results of TKA in patients with hemophilia using posterior cruciate ligament (PCL) sacrificing prostheses. Materials and Methods: The records of 18 consequtive hemophilic arthropathy patients who underwent total knee arthroplasty at our institution between 1998 and 2003 were retrospectively reviewed. The patients were evaluated by International Knee Society (IKS) Scoring system with specific attention to range of motion parameters and functional status at preoperative and postoperative clinical evaluation. Postoperative radiologic evaluation was based on the knee Society roent-genographic evaluation and scoring system. Results: The average age at operation was 34 years (range, 18–60) with an average follow-up of 51 months (range, 12–74). TKA resulted in an improvement in functional and knee scores, and range of motion parameters (p< 0,01). However, the functional status of the patients improved better than the knee status (p < 0,01). No signs of radiographic loosening were seen in any of the components at the final follow-up evaluation. There were two early hemarthrosis which required open lavage. Four patients had late complications. One patient had a periprosthetic fracture, which was treated with open reduction and internal fixation. Another patient had tibial tubercle avulsion and conservative treatment was choosen. One patient had revision secondary to progression of flexion contracture due to repetitive intraarticular hemorrhage, at the third year (26th month). One patient had deep infection. Conclusions: Our results demonstrate the excellent results in terms of functional scores and to a lesser extent in knee scores. Evaluation of the subcategories of the knee score demonstrated the limited restoration of motion as the reason for lower success rate in knee scores. Although PCL sacrificing designs allow better motion restoration, futher techniques should be developed to release the extraarticular structures that contribute to the flexion contracture, such as hamstring release

Aims. Mobile-bearing unicompartmental knee arthroplasty (UKA) with a flat tibial plateau has not performed well in the lateral compartment, leading to a high rate of dislocation. For this reason, the Domed Lateral UKA with a biconcave bearing was developed. However, medial and lateral tibial plateaus have asymmetric anatomical geometries, with a slightly dished medial and a convex lateral plateau. Therefore, the aim of this study was to evaluate the extent at which the normal knee kinematics were restored with different tibial insert designs using computational simulation. Methods. We developed three different tibial inserts having flat, conforming, and anatomy-mimetic superior surfaces, whereas the inferior surface in all was designed to be concave to prevent dislocation. Kinematics from four male subjects and one female subject were compared under deep knee bend activity. Results. The conforming design showed significantly different kinematics in femoral rollback and internal rotation compared to that of the intact knee. The flat design showed significantly different kinematics in femoral rotation during high flexion. The anatomy-mimetic design preserved normal knee kinematics in femoral rollback and internal rotation. Conclusion. The anatomy-mimetic design in lateral mobile UKA demonstrated restoration of normal knee kinematics. Such design may allow achievement of the long sought normal knee characteristics post-lateral mobile UKA. However, further in vivo and clinical studies are required to determine whether this design can truly achieve a more normal feeling of the knee and improved patient satisfaction. Cite this article: Bone Joint Res 2020;9(7):421–428

Introduction. Our unit has extensive experience with the use of Ilizarov circular frames for acute fracture and nonunion surgery. We have observed and analysed fracture healing patterns which question the role of relative stability in fracture healing and we offer limb mechanical axis restoration as a more important determinant. Aim. To assess for the presence of external callus, when only relative stability has been achieved but with anatomical restoration of the mechanical axis (ARMA). Methods. We retrospectively reviewed diametaphyseal proximal and distal tibial fractures treated with Ilizarov frame fixation in our unit between 2009 and 2017. We also reviewed cases where the Ilizarov frame technique had been used for complex femoral and humeral non-unions. Radiographs in 4 views were reviewed to assess bone healing, the presence of external callus and correction of lower limb mechanical axis. Results. 45 tibial plateau fractures, 42 distal tibial fractures and 20 humeral and 3 femoral non-unions were reviewed. Where ARMA was achieved, bone healing was observed to occur without external callus. ARMA proved more challenging in the distal tibia and where ARMA was not achieved external callus was visible during fracture healing. Conclusion. ARMA bone healing is reliable and occurs without formation of external callus, despite relative stability. This would suggest that external callus is produced not in response to just the magnitude of strain but also the direction of strain. Restoration of the mechanical axis is an important step in achieving union and needs to be considered when fixing fractures or treating non-unions