Restoration of leg length and offset is an important goal in total hip replacement. This paper reports a calliper-based technique to help achieve these goals by restoring the location of the centre of the femoral head. This was validated first by using a co-ordinate measuring machine to see how closely the calliper technique could record and restore the centre of the femoral head when simulating hip replacement on Sawbone femur, and secondly by using CT in patients undergoing hip replacement.

Results from the co-ordinate measuring machine showed that the centre of the femoral head was predicted by the calliper to within 4.3 mm for offset (mean 1.6 (95% confidence interval (CI) 0.4 to 2.8)) and 2.4 mm for vertical height (mean -0.6 (95% CI -1.4 to 0.2)). The CT scans showed that offset and vertical height were restored to within 8 mm (mean -1 (95% CI -2.1 to 0.6)) and -14 mm (mean 4 (95% CI 1.8 to 4.3)), respectively.

Accurate assessment and restoration of the centre of the femoral head is feasible with a calliper. It is quick, inexpensive, simple to use and can be applied to any design of femoral component.

Introduction and Objective. A proper restoration of hip biomechanics is fundamental to achieve satisfactory outcomes after total hip arthroplasty (THA). A global hip offset (GO) postoperatively reduction of more than 5 mm was known to impair hip functionality after THA. This study aimed to verify the restoration of the GO radiographic parameter after primary THA by the use of a cementless femoral stem available in three different offset options without length changing. Materials and Methods. From a consecutive series of 201 patients (201 hips) underwent primary cementless THA in our centre with a minimum 3-year follow up, 80 patients (80 hips) were available for complete radiographic evaluation for GO and limb length (LL) and clinical evaluation with Harris hip score (HHS). All patients received the same femoral stem with three different offset options (option A with – 5 mm offset, option B and option C with + 5 mm offset, constant for each sizes) without changing stem length. Results. Mean GO significantly increased by + 3 mm (P < 0.05) and mean LL significantly decreased by + 5 mm (P < 0.05) after surgery, meaning that postoperatively the limb length of the operated side increased by + 5 mm. HHS significantly improved from 56.3 points preoperatively to 95.8 postoperatively (P < 0.001). Offset option A was used in 1 hip (1%), B in 59 hips (74%) and C in 20 hips (25%). Conclusions. The femur is lateralized with a mean of + 5mm after surgery than, the native anatomy, whatever type of stem was used. Thus, the use of this 3-offset options femoral stem is effective in restoring the native biomechanical hip parameters as GO, even if 2 offset options were considered sufficient to restore GO

There are a growing number of younger patients with developmental dysplasia of hip, proximal femoral deformity and osteonecrosis seeking surgical intervention to restore quality of life, and the advent of ISTCs has resulted in a greater proportion of such cases being referred to existing NHS departments. Bone-saving hip athroplasty is often advocated for younger active patients, as they are potential candidates for subsequent revision arthroplasty. If resurfacing is contraindicated, short bone-conserving stems may be an option. The rationale for short stems in cementless total hip arthroplasty is proximal load transfer and absence of distal fixation, resulting in preserved femoral bone stock and avoidance of thigh pain. We have carried out 17 short stem hip replacements (Mini-hip, Corin Medical, Cirencester, UK) using ceramic bearings in 16 patients since June 2010. There were 14 females and 2 males, with a mean age of 50.1 years (range 35–63 years) at the time of the surgery. The etiology was osteoarthritis in 11, developmental dysplasia in 4, and osteonecrosis of the femoral head in one patient. All operations were performed through a conservative anterolateral (Bauer) approach. These patients are being followed and evaluated clinically with the Harris and Oxford hip scores, with follow-up at 6 weeks, 3 months, and annually thereafter. Initital results have been encouraging in terms of pain relief, restoration of leg length (one of the objectives in cases of shortening) and rage of movement. Radiological assessment has shown restoration of hip biomechanics. Specific techniques are required to address varus, valgus and femoral deformity with leg length inequality. There are two main groups of short stems, those that are neck-preserving and those that do not preserve the femoral neck. The latter group requires traditional techniques for revision. Another feature that differentiates them is the availability of modularity. The device we employed is neck-preserving and available with different neck lengths and offsets, which help in restoration of hip biomechanics. The advantage of such short stems may be preservation of proximal femoral bone stock, decreased stress shielding and the ease of potential revision. Such devices may be a consideration for patients with malformations of the proximal femur. Long-term follow-up will be of value in determining if perceived benefits are realised in practice

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

Aims. Surface replacement arthroplasty (SRA), compared with traditional total hip arthroplasty (THA), is more expensive and carries unique concern related to metal ions production and hypersensitivity. Additionally, SRA is a more demanding procedure with a decreased margin for error compared with THA. To justify its use, SRA must demonstrate comparable component survival and some clinical advantages. We therefore performed a systematic literature review to investigate the differences in complication rates, patient-reported outcomes, stress shielding, and hip biomechanics between SRA and THA. Materials and Methods. A systematic review of the literature was completed using MEDLINE and EMBASE search engines. Inclusion criteria were level I to level III articles that reported clinical outcomes following primary SRA compared with THA. An initial search yielded 2503 potential articles for inclusion. Exclusion criteria included review articles, level IV or level V evidence, less than one year’s follow-up, and previously reported data. In total, 27 articles with 4182 patients were available to analyze. Results. Fracture and infection rates were similar between SRA and THA, while dislocation rates were lower in SRA compared with THA. SRA demonstrated equivalent patient-reported outcome scores with greater activity scores and a return to high-level activities compared with THA. SRA more reliably restored native hip joint biomechanics and decreased stress shielding of the proximal femur compared with THA. Conclusion. In young active men with osteoarthritis, there is evidence that SRA offers some potential advantages over THA, including: improved return to high level activities and sport, restoration of native hip biomechanics, and decreased proximal femoral stress shielding. Continued long-term follow up is required to assess ultimate survivorship of SRA

The use of modular systems adds versatility to the implant system, better restoration of hip biomechanics and lower inventory to the hospital. There have been reports of high metal ions, ARMD reactions and high implant failure rates due to potential problems from taper failures. These are more common in metal-on-metal hip replacements, but are being also reported in other bearings. Between 2001 and 2010, we performed 383 consecutive metal-on-metal (MoM) THRs through a posterior approach, using a BHR cup and Birmingham modular head with one of three different stems, all with 12/14 tapers. The earliest 104 hips employed a cemented MS30 stem (Zimmer GmbH, Winterthur, Switzerland). Subsequent 256 were Synergy and then 23 Anthology (both uncemented and both Smith and Nephew Orthopaedics, Memphis TN USA). There was no significant difference in the average age at surgery (65.4 years cemented vs 65.6 uncemented, p = 0.69), gender ratio (1.68 vs 1.89, p = 0.64), or bearing diameter (46.7 vs 46.8, p = 0.31). The earlier 203 Synergy stems were monoblock heads, while the remaining uncemented stems included a tapered sleeve in addition. There were 3 deep infections and 11 debris-related failures (overall revision rate 4.9%). The revision rate from aseptic failures (ALTR, effusion, osteolysis or component loosening) is 2.87%. Kaplan-Meier analysis of the entire cohort showed a 10-year implant survival of 96.8% with revision for any reason as the end-point. Cemented stems had a 100% survival at 10 years and 98.6% at 12 years. The uncemented stems had a 93.8% survival at 10 years. Within the uncemented group, the monoblocks had a 5 and 10-year survival of 99.0% and 96.4% respectively while the sleeved had 98.7% (5 years) and 96.3% (7 years) and 82.5% at 8 years. Retreival analysis showed clear evidence of taper failure. Our experience suggests taper failure leading to ALTRs and its sequelae. Others have reported ALTR type reactions in metal on polyethylene and ceramic on polyethylene bearing types as well in bearing diameters ranging from 28mm to 40mm. There is a need to improve taper design especially for use with large heads, and in high demand patients

Introduction: The technology available for replacing/resurfacing the hip is constantly evolving. The surgeon can now choose from a wide array of componenets to perform a cemented, hybrid, uncemented total hip arthroplasty (THA) or resurfacing arthroplasty (RSA). The aim of our study was to evaluate and compare the restoration of hip biomechanics following insertion of three different, commonly used constructs. Methods: We compared the pre and postoperative radiographs from 40 patients who underwent cemented THA, 45 patients who underwent uncemented THA and 40 who underwent RSA. The femoral offset and limb length differences were measured, with reference to the normal contralateral hip. Results: Resurfacing resulted in a significant reduction in femoral offset, with accurate restoration of limb length. Both cemented and uncemented THA resulted in a significant increase in femoral offset and leg length. Uncemented THA resulted in the greatest degree of leg lengthening. Discusssion: Restoration of normal hip anatomy optimises biomechanical function and reduces wear of components. The RSA group had the most accurate restoration compared to the two other groups. The reduced femoral offset associated with the RSA group may reduce the lever arm of the abductor muscles however this is unlikely to be clinically important

Purpose: Clinical studies still show significant variability in offset and leg length reconstruction after 28mmTHA. Precise restoration of hip biomechanics is important since it reduces wear and improves stability, abductor function and patient satisfaction. There is a tendency to increase offset and leg length to ensure stability of 28mmTHA. This may not be needed with the more stable LDHTHA and hip resurfacing implants, therefore potentially improving the precision of the hip reconstruction. The aim of this study was to verify this assumption. Method: Leg length and femoral offset were measured on standardized digital radiographs with a computer software in 254 patients (49 HR, 74 LDHTHA, 132 28mmTHA) with unilateral hip involvement and compared to the normal contralateral side. Results: Femoral offset was increased in 72% of 28mmTHA (mean +3.3mm), 56% of LDHTHA (mean +1.0mm) and 8% of HR (mean −3.2mm) (intergroup differences p< 0.05). The mean LLI was greater after 28mmTHA (+2,29mm) vs. (−0.45mm for LDHTHA and −1.8mm for HR). The percentage of patients with increased leg length > 4mm was greater for 28mmTHA (11%) compared to LDHTHA (2.7%) and HR (2%). Conclusion: The stability afforded by the larger head of LDHTHA reduces the surgeon’s tendency to increased leg length and femoral offset to avoid instability as during 28mmTHA. In addition, compared to HR, LDHTHA allows more precise restoration of equal leg length and femoral offset in patient with greater pre operative deformities (low femoral offset and LLI > 1cm). LDHTHA may represent the most precise method of hip joint reconstruction

Introduction. Natural population variation in femoral morphology results in a large range of offsets, anteversion angles and lengths. During total hip arthroplasty, accurate restoration of hip biomechanics is essential to achieve good functional results. One option is to restore the anatomic hip rotation center. Alternatively, medializing the rotation center and compensating by increasing the femoral offset, reduces acetabular contact forces and increases the abductor lever arm. We investigated the ability of two cemented stem systems to restore hip biomechanics in an anatomic and medialized way. We compared an undersized “Exeter-type” of stem with three offset options and 18 sizes (CPT, Zimmer), to a line-to-line “Kerboul-type” of stem with proportional offset and 12 sizes (Centris, Mathys). Methods. Thirty CT scans of whole femora were segmented and the hip rotation center, proximal femoral axis and femoral length were determined with Mimics and 3-matic (Materialise). Using scripting functionality in the software, CAD design files of both stems were automatically sized and aligned along the proximal femoral axis to restore an anatomical and a 5 mm medialized hip rotation center. Stem size and position could be fine-tuned manually. The maximum distances between the prosthetic (PRC), the anatomic (ARC) and the medialized hip rotation center (MRC) were calculated (Fig. 1). Variations in femoral offset (ΔFO), anteroposterior (ΔAP) and proximodistal distance (ΔPD) were analyzed. Finally, the number of cases where the hip rotation center could be restored within 5 mm was reported. Results. Both implants allowed restoring the ARC accurately (mean distance PRC-ARC: CPT 0.97±0.88 mm, Centris 1.66±1.59 mm; mean difference ΔFO: CPT 0.09±0.19 mm, Centris 0.11±0.29 mm; mean difference ΔAP: CPT 0.12±1.22°, Centris 0.27±1.78 mm, mean difference ΔPD: CPT 0.04±0.44 mm, Centris 0.49±1.35 mm). The CPT stem allowed restoring the PRC within 5 mm of the ARC in all cases (max. 4.31 mm), whereas the Centris stem achieved this in only 28/30 hips (max. 6.72 mm) (Fig. 2). Aiming for a MRC was less satisfactory with both stems (mean distance PRC-MRC: CPT 1.38±1.63 mm, Centris 3.61±2.73 mm; mean difference ΔFO: CPT 0.09±0.10 mm, Centris 0.06±0.35 mm; mean difference ΔAP: CPT 0.17±2.02 mm, Centris 2.58±2.68 mm, mean difference ΔDP; CPT 0.28±0.67 mm, Centris 1.98±1.66 mm). The CPT stem allowed restoring the PRC within 5 mm of the MRC in 29/30 cases (max. 8.09 mm), whereas the Centris stem achieved this in only 25/30 cases (max. 11.15 mm) (Fig. 3). Discussion. Although both stem systems allowed restoring hip biomechanics accurately in most cases, the CPT system was superior to the Centris stem for achieving both ARC and MRC. This could be explained by more implant sizes (18 vs. 12) and undersized stems offering more freedom to correct version. Although medializing the hip rotation center offers biomechanical advantages, both stems had more difficulties achieving this. In some cases, differences between aimed and planned rotation centers were close to 1 cm which might negatively impact on clinical outcome. As such, to avoid suboptimal reconstructions with the available implants, templating is mandatory especially when aiming at a medialized reconstruction strategy

Introduction: Atypical femoral geometry and bone stock loss may make fitting a press-fit, traditional one-piece stem difficult, if not impossible. Modularity that permits independent fitting of the diaphysis, metaphysis, length, offset, and version may greatly facilitate reconstruction and ultimate clinical performance. Method: We prospectively evaluated the early clinical results of Exactech’s AcuMatch®. □. M-series prosthesis, a novel three-piece modular femoral stem. One hundred and twenty-seven were implanted in 114 patients. Ninety-one of these were primaries and 36 were revisions. The patients were followed prospectively and evaluated pre-operatively and at ≥2-year post-operatively. Results: Harris hip score for primaries was 37 pre-operatively and 87 at last follow-up. Harris hip score for revision group was 35 pre-operatively and 84 at last follow-up. Four dislocations occurred and one prosthesis fractured in a 330-pound patient with deficient abductors. One prosthesis has been removed, due to sepsis in the primary group. Conclusion: Through atraumatic milling of the bone and insertion of the implants, a minimal amount of intra-operative complications resulted. Ultimate restoration of hip biomechanics and soft tissue tension resulted in good clinical outcome with a very low dislocation rate

Introduction. Large diameter metal-on-metal hip arthroplasty (LDMMTHA) provides benefits of reduced dislocation rates and low wear. The use of modular systems allows better restoration of hip biomechanics. There have been reports of modular LDMMTHAs with tapered sleeves generating excessively high metal ions, due to possible mismatch between the titanium stem and the cobalt-chrome sleeve and the dual Morse tapers involved. We evaluated metal ion levels in LDMMTHA patients with and without a cobalt-chrome (CoCr) tapered sleeve. Methods. A cross-sectional series of 91 patients with proximal porous titanium alloy stem LDMMTHA with identical design CoCr bearings, attending a 1 to 2-year review were assessed with routine clinical and radiographic examinations, hip scores and metal ion analysis. Of these 65 had a single Morse taper between monoblock CoCr heads and the stems. Twentysix had a tapered cobalt-chrome sleeve in addition, with the resultant dual taper. Mean bearing diameter was 46 mm in both groups and mean age was 58 years in the monoblocks and 66 years in the tapered sleeve group. Results. Mean Oxford Hip score is worse in the tapered group (14.7) than in the monoblocks (12.6). All patients had well-functioning hips clinically and radiologically. Median blood cobalt and chromium are higher in the tapered sleeve (2.3μg/L and 1.8 μg/L) compared to the monoblocks (1.8 μg/L and 1.1 μg/L). Urine cobalt and chromium levels in the tapered sleeve (13.8 μg/24 hr and 5.3 μg/24 hr) also are higher than those in the monoblocks (12.2 μg/24 hr and 4.5 μg/24 hr respectively). Discussion and Conclusion. The limitation of this study is that it is a cross-sectional study. The results indicate that the use of a tapered sleeve in total hip arthroplasty does lead elevation of cobalt and chromium levels and the difference is statistically significant. However these levels are not as high as the levels reported with some other hip systems which have been withdrawn and the clinical significance of the elevated levels in the present study is unknown

Introduction: atypical femoral geometry and bone stock loss may make þtting a press þt traditional one-piece stem difþcult, if not impossible. modularity that permits independent þtting of the diaphysis, metaphysis, length, offset, and version may greatly facilitate reconstruction and ultimate clinical performance. Materials and methods: we prospectively evaluated the early clinical results of exactechñs acumatch? m-series prosthesis, a novel three-piece modular femoral stem. eighty-two were implanted in 80 patients. þfty-three of these were primaries and 29 were revisions. the patients were followed prospectively and evaluated with harris hip scores, range of motion, and complications pre-operatively and at ≥ 1-year post-operatively. Results: Harris hip score for primaries was 37 preoperatively and 84 at last follow-up. Harris hip score for revision group was 37 preopera-tively and 79 at last follow-up. Only one dislocation occurred in the 82 cases, in a patient who was revised for recurrent dislocation with deþcient abductors. There were three minor undisplaced calcar fractures in the primary group that did not alter the clinical outcome and in no case did the prosthesis penetrate the diaphysis. One prosthesis has been removed, and this was due to sepsis in the primary group. Conclusion: Through atraumatic milling of the bone and insertion of the implants, a minimal amount of intra-operative complications resulted. Ultimate restoration of hip biomechanics and soft tissue tension resulted in good clinical outcome with a very low dislocation rate

Introduction: The technology available for replacing/ resurfacing the hip joint is constantly evolving. The practicing surgeon can now choose from a wide array of components to perform a cemented, hybrid, uncemented total hip arthroplasty (THA), or a hip resurfacing. The potential advantages and disadvantages of all have been widely reported in the literature. The choice of implant depends on a number of factors, such as, patient age and level of activity, hip anatomy, and the surgeons’ preference and expertise. The aim of our study was to evaluate and compare the restoration of hip biomechanics following the insertion of three different, commonly used constructs. Methods: We compared the postoperative anteroposterior radiographs from 40 patients who underwent cemented THA, 45 patients who underwent uncemented THA and 40 who underwent Articular Surface Replacement (ASR). All procedures were carried out by a single consultant orthopaedic surgeon who was experienced in the insertion of all three different implant designs. The acetabular offset and height, and the femoral offset and limb length were measured, with reference to the normal contralateral hip, using accepted methods. Results – Hip resurfacing resulted in a significant reduction in femoral offset (p < 0.001), with accurate restoration of limb length. Both cemented and uncemented THA resulted in a significant increase in femoral offset, both also resulted in significant leg – lengthening (p< 0.001), this was more marked with uncemented THA’s. Radiological measurements of the acetabular reconstruction were similar in all groups. Discussion – Restoration of normal hip anatomy optimises biomechanical function and reduces wear of components. The ASR group had the most accurate restoration in comparison to the two other groups. The reduced femoral offset associated with the ASR group may reduce the lever arm of the abductor muscles however this is unlikely to be clinically significant

Introduction: The long-term results of total hip replacement can be improved by accurate placement of the implants, leading to restoration of hip biomechanics and prevention impingement from of implant malposition. Pelvic obliquity from patient positioning during surgery prevents accurate intra-operative assessment of component placement. Computer navigation assisted total hip replacement can potentially eliminate these problems by providing feedback on prosthetic placement during surgery. The purpose of our study was to assess the accuracy of the component placement in computer navigation assisted THRs performed in our institution. Methods: A total of 154 computer navigation assisted total hip arthroplasties performed between January 2004 and January 2005 were prospectively included in this study. Image free optical based navigation system (Navitrack™) was used. All procedures were performed by the senior author using MIS and open posterior approaches. Two independent observers performed analysis of the position of components and leg length discrepancy from standardized hip radiographs. Navigation values during surgery were compared with postoperative radiographic evaluation. Results: The mean abduction and anteversion angles of acetabular component in postoperative radiographs were 41.4 ± 6.1 and 22.6 ± 3.8 degrees respectively, in comparison to the navigation values of 40.9 ± 4.0 and 22.9 ± 3.6 degrees respectively. The femoral neck offset and leg length discrepancy calculated from navigation were with in a mean of 1.5mm and 2.8mm, respectively. There was one complication consisting of a peri-prosthetic femoral fracture that was recognised during surgery and treated with revision of the femoral component to a long-stem prosthesis. There was no early post-operative dislocation or deep infection in this series. Discussion: This study showed that computer navigation assisted THR provided predictable and reproducible results with accuracy in component placement and restorations of femoral neck offset and leg length

The vast majority of total-joint-replacement components utilized are modular to some degree. Modularity increases the surgeon’s options in both primary and revision THA. Modular prostheses allow the surgeon intra-operative versatility, allowing adjustment of leg length, offset, neck length, and version. This is particularly helpful in CHD, posttraumatic arthritis and in hip revision. Modularity may be applied also to the neck, enlarging the range of choice for difficult cases. Howeverusing of a modular interface increases risk of fretting, wear debris, and dissociation and mismatching of components. A series of 87 revision THA performed between 1997 and 2003 using modular neck was reviewed. The pros-theses are AnCA-Fit with a cementless titanium anatomical stem and Profemur with a tapered revision titanium stem. Both provided with a modular neck inserted by morse taper and a hemispheric press-fitted cup. All the implants have a ceramic-ceramic coupling. Four cases were performed due to recurrent dislocation and 83 for implant loosening. Retrieved necks were studied searching for corrosion. No cases of disassembly or fracture of the neck were observed. Two cases of dislocation were treated with brace. Analysis of retrieved necks confirmed the absence of corrosion. Leg length discrepancy decreased from 57.7% to 22%. One post-operative infection was successfully treated with debridment. Modular neck system allows to correct intraoperatively leg length and offset, choosing between five interchangeable necks available in two lengths: straight, varus-valgus, ante-retroverted. Restoration of hip biomechanics prevents instability. Removal of the neck allows a better surgical exposure when femoral stem is retained. Moreover it allows to maintain ceramic-ceramic coupling. Modular prosthesis has some problems related to risk of corrosion, fretting, fracture or dislocation of components. We observed no cases of disassembly of components or fracture and comparative analysis between retrieved necks and those experimentally studied confirmed absence of corrosion

We present the results of custom made cementless implants for treatment of osteoarthritis due to congenital disease of hip and osteonecrosis due to other diseases, where the normal anatomy was severely modified and it was impossible to insert the smallest available implant. There were 43 patients with 52 hips, 6 males – 46 females. The mean age was 48years (22–61). The mean follow-up was 24 months (1–48). There were 32 patients with low dislocation, 14 with high dislocation, 1 with infantile septic arthritis, 1 with Hodgkin disease, 1 with dysplasia, 1 with ankylosing spondylitis, 1 with congenital varus hip and 1 with Perthes disease. Our protocol was consisted of plain radiographs and CT of the acetabulum, femur, knee condylars and foot in order to be evaluated the bone stock of acetabulum and the femur anteversion. All the patients were evaluated – according to the Merle D’ Aubigne score – two, three and every six months after the operation. There was one complication with a proximal femur fracture in a high dislocated hip during the operation and two complications postoperatively. Both of them were high dislocated hips, and the one had paresis of sciatic nerve, that it recovered. The other had septic loosening and was undertaken revision in two stages. All the patients improved in pain, in walking ability and in range of motion. The impossibility of using the smallest available implant due to the high deformity and the young age led us to use custom made implant. Although a long follow-up is required for these procedures the first results are very encouraging according to the recovery of the patients which were related to the restoration of hip biomechanics provided by the three dimensional neck orientation

Purpose. The ultimate goal in total hip arthroplasty is not only to relieve the pain but also to restore original hip joint biomechanics. The average femoral neck-shaft angle(FNSA) in Korean tend to have more varus pattern. Since most of conventional femoral stems have relatively high, single, fixed neck shaft angle, it's not easy to restore vertical and horizontal offset exactly especially in Korean people. This study demonstrates the advantages of dual offset(especially high-offset) stem for restoring original biomechanics of hip joint during the total hip arthroplasty in Korean. Materials and Methods. 180 hips of 155 patients who underwent total hip arthroplasty using one of the standard(132°) or extended(127°) offset Accolade cementless stems were evaluated retrospectively. Offset of stem was chosen according to the patient's own FNSA in preoperative templating. In a morphometric study, neck-shaft angle of proximal femur, vertical offset and horizontal offset, abductor moment arm were measured on preoperative and postoperative both hip AP radiographs and the differences and correlation of each parameters, between operated hip and original non-operated hip which had no deformity (preoperative ipsilateral or postoperative contralateral hip), were analyzed. Results. The standard stems were used in 34 hips and extended offset stems were used in 146 hips. The FNSA of non-operated hip was an average of 129.8°(127.2°□135.8°) in standard group and mean 125.4°(122.7°□129.9°) in extended offset group. The FNSA of operated hip was an average of 131.6° and 127.1° in each group. In the statistical analysis, there was no significant difference of mean horizontal and abductor moment arm between operated hip and non-operated hip in both groups and the restoration of horizontal offset and abductor moment arm showed(p=0.217, p=0.093) significant positive correlation(R=0.870, R=0.851) to the original value. However, vertical offset was increased an average of 1.4mm in operated hip and there was statistical significance. Restoration of vertical offset showed positive correlation to original value (R=0.845). Conclusion. Dual- or multi-offset stem, especially extended offset stem can provide easy restoration of hip biomechanics and soft tissue tension without significant alteration of leg length especially in Korean with more varus femoral neck compared to Caucacian. Precise radiographic measurements of original hip and application of proper-offset stem should be taken in order to restore ideal hip biomechanics successfully and easily. A use of a proper offset stem can afford to enhance joint stability and implant longevity by improving soft-tissue tension and reducing resultant force, and it will guarantee a successful results after total hip arthroplasty in the aspect of function and longevity

Restoration of hip biomechanics is an important determinant of outcome in hip replacement. Pre-operative templating is considered important in preoperative planning, and this trend is likely to develop further to satisfy consumer demand and to facilitate navigated surgery, particularly as digitisation of radiographs becomes established. We aimed to establish how closely natural femoral offset could be reproduced using the manufacturers’ templates for 10 femoral stems in common use in the U.K. The most frequently used femoral components from the U.K. national joint registry and uncemented) were identified, and the CPS-Plus stem was added, as this is in use in our unit. A series of 24 consecutive pre-operative radiographs from patients who had undergone unilateral total hip replacement for unilateral osteoarthritis of the hip were reviewed. The non-operated on side of the pelvic radiographs was templated as described by Schmalzreid. 3 surgeons of variable experience (junior trainee, senior trainee, consultant) performed the assessment. The standard deviation of change in offset between the templated centre of rotation and the normal centre of rotation of the set of radiographs for each prosthesis was then calculated allowing a ranking. The most accurate template was the CPS with a mean standard deviation of 1.92mm followed in rank order by: CPT 2.21mm, C Stem 2.42mm, Stanmore 3.02 mm Exeter 3.06 mm, ABG II 3.54mm, Charnley 3.54 mm, Corail 3.63 mm, Furlong HAC 4.2 mm and Furlong modular 4.86mm. There is wide variation in the ability of the femoral templates to reproduce normal femoral anatomy in a series of standard pre-operative hip radiographs. The more modern cemented polished tapered stems with high modularity appear best able to reproduce femoral offset. Nevertheless, some older monoblock stems, despite poor templating characteristics, are known to be associated with acceptable clinical results. The coming years are likely to be witness to changes in patient expectations and radiograph storage. Implant design and digital templates will need to improve apace with these changes, to ensure accurate preoperative planning

Background: Revision hip arthroplasty in the presence of extensive proximal femoral bone loss constitutes a major challenge. Several reconstruction alternatives have been introduced to deal with the problem of severe proximal bone loss. One of the techniques widely used is bridging the bone defect with the use of a distally fixing implant. The Link- MP reconstruction prosthesis is such a diaphyseal-fixing stem and we report on the early experience with its use. Methods: The prosthesis has a modular design that allows restoration of hip biomechanics, femoral anteversion and leg length. It is made of a Titanium alloy with a micro-porous surface. The distal part (the stem) has a conical shape that allows cementless anchoring in the femoral diaphysis and it also has 8 or 10 longitudinal grooves, which provide rotational stability. We report on the early results of its use, mean follow-up 30 months, (range, 9–54 months). Between 1997 and 2001, 32 hip revisions using the Link MP reconstruction prosthesis were performed in 31 patients. There were 13 females and 18 males with a mean age of 65 years (range 35 – 82). The indication for the revision operation was aseptic loosening in twenty-one cases, septic loosening in six and periprosthetic fracture in five cases. Cancellous bone allografts were used in 25 patients. Patients with proven infection were treated by a two-stage procedure. Results: The mean Merle d’ Aubigne score increased from 6.8 preoperatively to 14.1 postoperatively and there was radiographic evidence of bone regeneration in the proximal femur in 80% of the patients. There were two intraoperative femoral fractures, which didn’t necessitate more than an extension of the partial weight bearing period and healed without complications. No stem was re-revised. Conclusions: The early results with the use of the Link MP reconstruction prosthesis are encouraging, as shown by the improved patient functional status, the low incidence of complications and the observed proximal femoral bone regeneration

Introduction: Restoration of hip biomechanics is an important part of successful total hip replacement. Preoperative templating acts as a guide to selection of size and positioning of prostheses to enable this. We aimed to Establish how closely natural femoral offset could be reproduced using the manufacturers templates for 10 femoral stems in common use in the U.K. Method: The10 most frequently used femoral components from the U.K. national joint registry (cemented and un-cemented) were identified. Sets of templates for these designs were used to template a series of 47 consecutive pre-operative radiographs from patients who had undergone unilateral total hip replacement for unilateral osteoarthritis of the hip. The non-operated on side of the pelvic radiographs were templated using the 10 sets of templates according to the technique of Schmalzreid. This demonstrated how much the offset of the hip would be changed if that prosthesis were selected and implanted in the templated position. 3 different surgeons performed the complete process. The standard deviation of change in offset between the templated centre of rotation and the normal centre of rotation of the set of radiographs for each prosthesis was then calculated allowing us to rank the templates and hence implants according to their ability to reproduce the normal anatomical offset. Results: The most accurate template was the CPS with a Root Mean Square Error of 2.0mm followed in rank order by: C stem 2.16, CPT 2.40, Exeter 3.23, Stanmore 3.28, Charnley 3.65, Corail 3.72, ABG II 4.30, Furlong HAC 5.08, Furlong modular 7.14. Discussion: There is fairly wide variation in the ability of the femoral prosthesis templates to reproduce normal femoral offset in a series of standard pre-operative hip radiographs. The more modern polished tapered stems with high modularity were best able to reproduce femoral offset. There is however no correlation between the prostheses ability to restore offset and clinical results. Some of the older less modular stems, which were unable to get close to normal offset, have some of the best longterm clinical results. With the increasing digitalisation of radiographs a change in the method of templating is required. This may allow manufactures to re-examine their templates and improve the accuracy of this process