Conventional uncemented femoral implants provide dependable long-term fixation in patients with a wide range of functional requirements. Yet challenges associated with proximal–distal femoral dimensional mismatch, preservation of bone stock, and minimally invasive approaches have led to exploration into alternative implant designs. Short stem designs focusing on a stable metaphyseal fit have emerged to address these issues in total hip replacement (THR). Uncemented metaphyseal-engaging short stem implants are stable and are associated with proximal bone remodeling closer to the metaphysis when compared with conventional stems and they also have comparable clinical performances. Short stem metaphyseal-engaging implants can meet the goals of a successful THR, including tolerating a high level of patient function, as well as durable fixation. Cite this article: Bone Joint J 2013;95-B, Supple A:57–62

Aims. The Exeter short stem was designed for patients with Dorr type A femora and short-term results are promising. The aim of this study was to evaluate the minimum five-year stem migration pattern of Exeter short stems in comparison with Exeter standard stems. Methods. In this case-control study, 25 patients (22 female) at mean age of 78 years (70 to 89) received cemented Exeter short stem (case group). Cases were selected based on Dorr type A femora and matched first by Dorr type A and then age to a control cohort of 21 patients (11 female) at mean age of 74 years (70 to 89) who received with cemented Exeter standard stems (control group). Preoperatively, all patients had primary hip osteoarthritis and no osteoporosis as confirmed by dual X-ray absorptiometry scanning. Patients were followed with radiostereometry for evaluation of stem migration (primary endpoint), evaluation of cement quality, and Oxford Hip Score. Measurements were taken preoperatively, and at three, 12, and 24 months and a minimum five-year follow-up. Results. At three months, subsidence of the short stem -0.87 mm (95% confidence interval (CI) -1.07 to -0.67) was lower compared to the standard stem -1.59 mm (95% CI -1.82 to -1.36; p < 0.001). Both stems continued a similar pattern of subsidence until five-year follow-up. At five-year follow-up, the short stem had subsided mean -1.67 mm (95% CI -1.98 to -1.36) compared to mean -2.67 mm (95% CI -3.03 to -2.32) for the standard stem (p < 0.001). Subsidence was not influenced by preoperative bone quality (osteopenia vs normal) or cement mantle thickness. Conclusion. The standard Exeter stem had more early subsidence compared with the short Exeter stem in patients with Dorr type A femora, but thereafter a similar migration pattern of subsidence until minimum five years follow-up. Both the standard and the short Exeter stems subside. The standard stem subsides more compared to the short stem in Dorr type A femurs. Subsidence of the Exeter stems was not affected by cement mantle thickness. Cite this article: Bone Jt Open 2023;4(7):507–515

Shoulder arthroplasty humeral stem design has evolved to accommodate patient anatomy characteristics. As a result, stems are available in numerous shapes, coatings, lengths, sizes, and vary by fixation method. This abundance of stem options creates a surgical paradox of choice. Metrics describing stem stability, including a stem's resistance to subsidence and micromotion, are important factors that should influence stem selection, but have yet to be assessed in response to the diametral (i.e., thickness) sizing of short stem humeral implants. Eight paired cadaveric humeri (age = 75±15 years) were reconstructed with surgeon selected ‘standard’ sized short-stemmed humeral implants, as well as 2mm ‘oversized’ implants. Stem sizing conditions were randomized to left and right humeral pairs. Following implantation, an anteroposterior radiograph was taken of each stem and the metaphyseal and diaphyseal fill ratios were quantified. Each humerus was then potted in polymethyl methacrylate bone cement and subjected to 2000 cycles of 90º forward flexion loading. At regular intervals during loading, stem subsidence and micromotion were assessed using a validated system of two optical markers attached to the stem and humeral pot (accuracy of <15µm). The metaphyseal fill ratio did not differ significantly between the oversized and standard stems (0.50±0.06 vs 0.50±0.10; P = 0.997, Power = 0.05); however, the diaphyseal fill ratio did (0.52±0.06 vs 0.45±0.07; P < 0.001, Power = 1.0). Neither fill ratio correlated significantly with stem subsidence or micromotion. Stem subsidence and micromotion were found to plateau following 400 cycles of loading. Oversizing stem thickness prevented implant head-back contact in all but one specimen with the least dense metaphyseal bone, while standard sizing only yielded incomplete head-back contact in the two subjects with the densest bone. Oversized stems subsided significantly less than their standard counterparts (standard: 1.4±0.6mm, oversized: 0.5±0.5mm; P = 0.018, Power = 0.748;), and resulted in slightly more micromotion (standard: 169±59µm, oversized: 187±52µm, P = 0.506, Power = 0.094,). Short stem diametral sizing (i.e., thickness) has an impact on stem subsidence and micromotion following humeral arthroplasty. In both cases, the resulting three-dimensional stem micromotion exceeded, the 150µm limit suggested for bone ingrowth, although that limit was derived from a uniaxial assessment. Though not statistically significant, the increased stem micromotion associated with stem oversizing may in-part be attributed to over-compacting the cancellous bed during broaching, which creates a denser, potentially smoother, interface, though this influence requires further assessment. The findings of the present investigation highlight the importance of proper short stem diametral sizing, as even a relatively small, 2mm, increase can negatively impact the subsidence and micromotion of the stem-bone construct. Future work should focus on developing tools and methods to support surgeons in what is currently a subjective process of stem selection

Abstract. Objective. Short-stem total hip arthroplasty (THA) aims to preserve the proximal bone stock for future revisions, so that the first revision should resemble a primary intervention rather than a revision. This study aimed to compare the clinical and radiological outcomes in revision THA after failed short stem versus after failed conventional stem THA. Methods. This study included forty-five patients with revision THA divided into three groups (15 each); group A: revision after short stem, group B: revision after conventional cementless stem and group C revision after conventional cemented stem. The studied groups were compared regarding 31 variables including demographic data, details of the primary and revision procedures, postoperative radiological subsidence, hospital stay, time for full weight bearing (FWB), preoperative and postoperative clinical scores. Results. Early stem subsidence (40%) was the main indication of revision in group A compared to peri-prosthetic femoral fractures (PFFs) (73.3%) and aseptic loosening (53.3%) in group B and C respectively (P=0.021). The mean time to revision was significantly shorter in group A (15 months) compared to 95.33 and 189.40 months in group B and C respectively. (P=0.005). Sixty % (9 patients) in group A were revised in the first year. The mean operative time, blood loss, postoperative blood transfusion and hospital stay were significantly lower in group A compared to group B and C (P<0.001, <0.001, 0.002 and 0.001 respectively). Revisions in group A were performed using either short stems (13.3%) or conventional stems (86.7%) whilst 80% of patients needed long stems and 20% of patients needed conventional stems in group B and C (P<0.001). The mean postoperative Harris Hip Score (HHS) at the latest follow up was 87.07, 87.53 and 85.47 in group A, B and C respectively. All PFFS had excellent results according to Beal's and Tower's criteria; all fractures healed and the implants were stable. Conclusion. The most common cause of failure of short stems is early stem subsidence. Short stem THA has specific indications and patient selection is very crucial. Preoperative templating for short stems and a detailed analysis of the individual patient anatomy in anteroposterior and lateral views are mandatory to predict the correct implant size more accurately. The use of intraoperative imaging can verify the sizing, implant position, and sufficient contact with the lateral cortex. Revision of short stem THA resembled the primary THA. If a standard implant can be used in a surgical revision instead of a longer revision stem, this can be considered as an advantage for the hip arthroplasty treatment concept. However, this only applies if the longevity of the first treatment with a short stem is comparable with that of a standard stem. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

We sought to determine the short to medium-term clinical and radiographic outcomes using a short stem in young adults with a proximal femoral deformity (PFD). We prospectively studied 31 patients (35 hips) with PFDs treated with an uncemented primary THA using a short stem with cervicometaphyseal fixation between 2011–2018. There were 19 male (23 hips) and 12 female (12 hips) patients, with a mean BMI of 26.7±4.1 kg/m. 2. Twelve cases had a previous surgical procedure, and six of them were failed childhood osteotomies. Mean age of the series was 44±12 years, mean follow-up was 81±27 months and no patients were lost to follow-up. PFDs were categorized according to a modified Berry´s classification. Average preoperative leg-length discrepancy (LLD) was −16.3 mm (−50 to 2). At a mean time of 81 months of follow-up, survival rate was 97% taking revision of the stem for any reason and 100% for aseptic loosening as endpoints. No additional femoral osteotomy was required in any case. Average surgical time was 66 minutes (45 to 100). There was a significant improvement in the mHHS score when comparing preoperative and postoperative values (47.3±10.6 vs. 92.3±3.7, p=0.0001). Postoperative LLD was in average 1 mm (−9 to 18) (p=0.0001). According to Engh's criteria, all stems were classified as stable without signs of loosening. Postoperative complications included 1 pulmonary embolism, 1 neurogenic sciatic pain, 1 transient sciatic nerve palsy that recovered completely after six months, and 2 acute periprosthetic joint infections. One patient suffered a Vancouver B2 periprosthetic femoral fracture 45 days after surgery and was revised with a modular distally fixed uncemented fluted stem. A type 2B short stem evidenced promising outcomes at short to medium-term follow up in young adult patients with PFDs, avoiding the need for corrective osteotomies and a revision stem

The use of short stems has become more popular with the increased interest in less invasive approaches for total hip arthroplasty. The curved broaches and stem can be inserted along a curved track to avoid the abductor attachments. Short stems have the potential of being more bone conserving by allowing for higher neck retention, maintenance of the medial greater trochanter, and preferential stress transfer to the proximal femur. An initial experience with 500 new short stems (Fitmore, Zimmer Orthopedics) stems used for total hip arthroplasty is reported. No stems have been revised for aseptic loosening

Use of a short femoral stem for total hip replacement is not a new idea. Morrey first reported on the results of the Mayo Conservative Stem (Zimmer) in 1989. A short femoral stem can also be soft tissue conserving by allowing for a curved insertion track avoiding the abductor attachments. These concepts have made use of a short femoral stem attractive for use in less invasive total hip surgical approaches. The goal of a short femoral stem is to be bone conserving and provide preferential stress transfer to the proximal femur. This may make the short stem desirable for most total hips regardless of surgical approach. The proximal femur has considerable variability in shape, canal size, and offset. This makes a single geometry short stem potentially unstable in some anatomic variants without having a longer stem to resist varus bending moments or obtain diaphyseal stability. The Fitmore Stem (Zimmer) has addressed these anatomic variants by having three different shaped stems with different offsets. The presenter has implanted over 1,000 short stems, using them for both standard and less invasive surgical approaches. There is a learning curve when using these short stems. Initially some stems were undersized and inserted in some varus. Thirty-four percent of the first 100 short stems inserted had measurable subsidence. However, all stabilised with no further subsidence. Rarely, subsidence now occurs with attention to preoperative planning for size and improved surgical technique. The surgical technique for insertion of this short stem is different from a conventional length total hip stem. The canal is broached along a curved track with a posterior and lateral moment applied to the broach. Use of the largest size broach that doesn't sink with moderate impaction forces is necessary to maximally contact the medial and lateral proximal cortices to lessen stem subsidence. Four of over 1,000 stems have been revised for postoperative peri-prosthetic fracture after falls. Two stems were revised for late infection but were not clinically loose. No stems have been revised for aseptic loosening

Use of a short femoral stem for total hip replacement is not a new idea. Morrey first reported on the results of the Mayo Conservative Stem (Zimmer) in 1989. A short femoral stem can also be soft tissue conserving by allowing for a curved insertion track avoiding the abductor attachments. These concepts have made use of a short femoral stem attractive for use in less invasive total hip surgical approaches. The goal of a short femoral stem is to be bone conserving and provide preferential stress transfer to the proximal femur. This may make the short stem desirable for most total hips regardless of surgical approach. The proximal femur has considerable variability in shape, canal size, and offset. This makes a single geometry short stem potentially unstable in some anatomic variants without having a longer stem to resist varus bending moments or obtain diaphyseal stability. The Fitmore Stem (Zimmer) has addressed these anatomic variants by having three different shaped stems with different offsets. The presenter has implanted over 1,000 short stems, using them for both standard and less invasive surgical approaches, and in all bone types. There is a learning curve when using these short stems. Initially some stems were undersized and inserted in some varus. Thirty-four percent of the first 100 short stems inserted had measurable subsidence. However, all stabilised with no further subsidence. Rarely, subsidence now occurs with attention to pre-operative planning for size and improved surgical technique. The surgical technique for insertion of this short stem is different from a conventional length total hip stem. The canal is broached along a curved track with a posterior and lateral moment applied to the broach. Use of the largest size broach that doesn't sink with moderate impaction forces is necessary to maximally contact the medial and lateral proximal cortices to lessen stem subsidence. Four of over 1,000 stems have been revised for post-operative peri-prosthetic fracture after falls. Two stems were revised for late infection but were not clinically loose. No stems have been revised for aseptic loosening

Objectives. Periprosthetic femoral fractures (PFFs) have a higher incidence with cementless stems. The highest incidence among various cementless stem types was observed with double-wedged stems. Short stems have been introduced as a bone-preserving alternative with a higher incidence of PFF in some studies. The purpose of this study was a direct load-to-failure comparison of a double-wedged cementless stem and a short cementless stem in a cadaveric fracture model. Methods. Eight hips from four human cadaveric specimens (age mean 76 years (60 to 89)) and eight fourth-generation composite femurs were used. None of the cadaveric specimens had compromised quality (mean T value 0.4 (-1.0 to 5.7)). Each specimen from a pair randomly received either a double-wedged stem or a short stem. A materials testing machine was used for lateral load-to-failure test of up to a maximal load of 5000 N. Results. Mean load at failure of the double-wedged stem was 2540 N (1845 to 2995) and 1867 N (1135 to 2345) for the short stem (p < 0.001). All specimens showed the same fracture pattern, consistent with a Vancouver B2 fracture. The double-wedged stem was able to sustain a higher load than its short-stemmed counterpart in all cases. Failure force was not correlated to the bone mineral density (p = 0.718). Conclusion. Short stems have a significantly lower primary load at failure compared with double-wedged stems in both cadaveric and composite specimens. Surgeons should consider this biomechanical property when deciding on the use of short femoral stem. Cite this article: A. Klasan, M. Bäumlein, P. Dworschak, C. Bliemel, T. Neri, M. D. Schofer, T. J. Heyse. Short stems have lower load at failure than double-wedged stems in a cadaveric cementless fracture model. Bone Joint Res 2019;8:489–494. DOI: 10.1302/2046-3758.810.BJR-2019-0051.R1

A large number of short stem prosthesis for hip arthroplasty has been introduced in the last years. The main aim of this device is to preserve the proximal bone stock in order to facilitate revisions in the future. Furthermore there is an increase in young and active patients in total hip arthroplasty that's why it's important to consider minimally invasive, muscle-considering procedures. Short stems allow to make minimal invasive approaches easier and improve the biomechanical reconstruction. However, there is a large increase of publication about short stems there is still little data about survival and revision rates. We report about the outcome of 81 patients, who have recieved NANOS short stem prosthesis between October 2012 and April 2014. The average age of the patient was 61,6. The oldest patient was 78 years old and our youngest patient was 41 years old. The main diagnoses were osteoarthritis in 67 patients, dysplastic osteoarthritis in 8 patients and avascular necrosis of the femoral head in 6 patients. We have included 37 female patients and 44 male patients. 3 patients had the surgery on both sides. The average operating time was 75,2 min ± 20,1 min and the average grading of patients for surgical procedures of the American Society of Anesthesiologists was 1,8±0,7. The patients were hospitalized 9,6 days ± 2,9 days. The average BMI was 28,2±5,2. Along with demographic data and co-morbidities, the Harris Hip Score was recorded pre-operatively and at follow-up. The Harris Hip Score increased from 36,6 ± 14,5 pre-operatively to 94,5 ± 8,8 at the final follow-up. None of the 81 stems were revised this corresponds to a to a survival rate of 100%. Two of the patients suffered from a hip dislocation which was treated in both cases conservative. In further consequence unfortunately one of those patients thrombosed and suffered from a pulmonary embolism. The x-rays haven't shown any radiolucent lines in any patients. All in all our patients reported about an high post-operative satisfaction. The clinical and radiographic results encouraged us to continue to use short stems with metaphyseal anchorage. However, there must be more long-term results to confirm our excellent mid term results

As an increasing number of young, active large patients become candidates for total hip replacements, there is an increasingly urgent need to identify arthroplasties that will be durable, highly functional and amenable to possible future successful revision. In an era when cemented femoral stems were the primary implant option, the concept of a surface replacement was attractive and, perhaps, appropriate. However, cementless femoral stems of many designs now provide dependable long term fixation and excellent, near normal function. However, a number of issues related to cementless stem fixation could be further improved: . –. Optimisation of load transfer to proximal femur to minimize fracture risk and maximize bone preservation. –. Elimination of proximal-distal mismatch concerns, including bowed femurs. –. Facilitation of femoral stem insertion, especially with MIS THA exposures. –. Facilitation of revision with implants capable of providing durable fixation for active patients. The potential benefits of short stem femoral THA implants include: . –. Ease of insertion. –. Avoidance of issues related to proximal-distal anatomic mismatch or variations in proximal femoral diaphyseal anatomy (e.g. femoral bowing). –. Facilitation of MIS surgical approaches, especially anterior exposures. –. Optimisation of proximal femoral load transfer with consequent maximisation of proximal bone preservation. However, a number of potential drawbacks may be associated with the use of cementless short stems: . –. Initial and durable fixation may be highly sensitive to implant design and surface treatment. –. The implants may not be suitable for patients with osteopenia. Consistent, reliable identification of patients appropriate for these implants may be difficult. –. There may be a significant learning curve associated with the use of short stem implants. At this time, it is important to realize that not all short stem implants are equal. In view of the reliability of a large number of uncemented femoral stems of conventional length, surgeons should base their use of specific short stems upon clinical evidence of their safety and durability

Objective. Recently, the short stem, taken on preservation of the femoral bone, is available on total hip arthroplasty and on femoral head prosthetic replacement. The handling of the short stem is easier than that of standard stem on implantation of femur. However, it would be difficult to make the direction of stem axis straight in femoral marrow cavity. Actually we experienced that the lateral cortical bone of the proximal femur was ground unevenly on rasping for implantation of the short stem. The aim of this study was to identify the efficacy of dulled rasp on implanting the short stem. Subjects and Methods. We examined 42 hips of 39 patients who underwent the primary total hip arthroplasties with short stems in our institution from August 2011 to April 2014. Primary diseases were 28 osteoarthritides, 6 idiopathic osteonecrosises of the femoral heads and 5 others. We categorized N group as using standard rasp with sharpened blades and M group as using modified rasp with dulled blades named ‘Mild Rasp’, and analyzed with the statistical methods. Results. The numbers of N group was 27 hips, consisting of 15 males and 12 females, with a mean age of 60.0 years and a mean body mass index (BMI) of 25.2. The mean time of operation was 149.9 minutes, and the mean amount of bleeding during surgery was 761.0 ml. The median of stem size was 13 (range, 5–17) and the mean declination angle from the femoral axis was 2.9. The numbers of M group was 15 hips, consisting of 4 males and 11 females, with a mean age of 63.1 years and a mean BMI of 27.3. The mean time of operation was 187.1 minutes, and the mean amount of bleeding during surgery was 875.7 ml. The median of stem size was 11 (range, 6–14) and the mean declination angle from the femoral axis was 1.3. The time of operation of the M group was significant longer than that of N group (p = 0.016). The declination angle from the femoral axis of the M group was significant smaller than that of N group (p = 0.005). The other parameters were not significant difference between M group and N group. Discussion. When the short stems were implanted, it was reported to tend to be valgus position in femoral marrow cavity. We considered that it would be easy to grind the cortical bone of the proximal cavity by the rasp with sharpened blades. Therefor we used the rasp with dulled blades, the efficacy was indicated. Conclusions. ‘Mild Rasp’ would be useful for positioning more straight against the femoral axis on total hip arthroplasty

The use of short femoral components in primary total hip arthroplasty (THA) represents an attractive option. Advocates tout bone preservation and ease of use in less invasive surgical approaches. In 2006 we adopted the concept and have had experience with over 5,700 short, tapered, titanium, porous plasma-sprayed stems in patients undergoing primary THA. The plasma-sprayed portion of this stem is similar to the longer, standard length TaperLoc stem, with shortening resulting from a 3 cm reduction in length of the distal portion of the implant. However, the proximal aspect maintains the same flat, tapered wedge proximal geometry as the standard stem. During insertion in some femurs it was noted that distal canal fill occurred preferentially to proximal canal fill. This required distal broaching in order to accommodate a larger stem. In an effort to avoid this clinical situation and to improve the gradual off-loading that is the goal of a tapered geometry, the design was modified in 2011 to reduce the profile of the component. Other modifications include a lower caput-collum-diaphyseal (CCD) angle to enhance horizontal offset restoration without increasing leg length, width sizing from 5–18 mm in 1 mm increments, and polished neck flats to increase range of motion. Undoubtedly, porous plasma sprayed tapered titanium stems are successful in primary THA. Short stems can better accommodate proximal-distal femoral mismatch, particularly in hips with a large metaphysis and a narrow diaphysis, hips with an excessively bowed femur, and hips with severe deformity such as that encountered with developmental dysplasia and post-traumatic arthritis. Short stems violate less femoral bone stock, allowing for more favorable conditions should revision surgery become necessary. The concept of a short stem is appealing to patients, who perceive it as less invasive. In addition, short stems facilitate shorter incision surgery and operative approaches such as the muscle-sparing anterior supine intermuscular. Increased canal fill has been associated with distal cortical hypertrophy. Reducing the distal portion of the stem has reduced the incidence of distal canal fill, and allows for placement of a slightly larger implant

Introduction. Since 1989 we have been using custom lateral-flare stems. Using this stem, its lateral flare can produce high proximal fit and less fit in distal part. Applying this automatic designing software to the average femoral geometries, we can make off the shelf high proximal fit stem (Revelation ®). Putting the off the shelf stem, the original center of the femoral heads were well reproduced. But in DDH cases, severe deformities around hip sometimes make complicated difficulty for better functional reconstruction. They are high hip center such as Crowe II-IV, shortening of the femoral neck, high anteversion etc. DDH cases are well known to have higher anteversion than non DDH cases. There would be no definite explanations for it. The high anteversion would not always be harmful for the preoperative patients. But in some cases, osteophytes are observed at posterior side of the femoral head which make another sphere with different centre. We can guess that the patient's biomechanics had not been matched with the original anteversion. Then posterior osteophytes can correct inappropriate anteversion (self-reduction.) (Fig.1) In those patients, reduction of the anteversion by putting stems twisted into the canal or using modular stems are sometimes done by the surgeons' decision. Younger DDH cases can also be treated with THA, because of the complicated deformities or biomechanical disorders. Short stems are expected to reduce operative invasion and stress shielding then can reserve bone quality and quantity. From these point of view to improve the understanding of the characteristics of the DDH anteversion, and design a DDH oriented short stem could be one of good solution for those cases. Method. For the better understanding of the high anteversion 57 femora (mean anteversion: 34.4 deg.) were analyzed slice by slice. The direction of femoral head centre, lesser trochanter (LTR), linea aspera (aspera) just below LTR, aspera in the middle of the femur and aspera between the last 2 sections. All of the directions were assessed from PC line. To clarify the meaning of the head osteophytes, 35 operated cases were analyzed the extent of the head osteophytes. According to the results, a DDH oriented short stem was designed. Results. Even with the different anteversion, femoral head centres and LTRs were located within limited angle (51.4 +/−7.9 deg.) But aspera just below the LTR had no relation to the LTR direction, but always kept within limited angle (102.0 +/− 4.5) to the PC line. This means that DDH cases have proximal femurs of normal shape. But they are only twisted around the level just below the LTR. From this result, stems for DDH cases can have the same shape with normal stem inside the canal. The posterior osteophytes had reduced 4.6+/− 3.0 degree in average independently to the extent of anteversion. There was no tendency that higher anteversion cases have higher self-reduction angle. the stems were give the same shape inside the canal with stems for non DDH cases but its femoral head center was located with 5 degrees less anteversion

The current concepts of proximal femoral fixation in hip arthroplasty can be divided into three groups: the surface replacement concept, the femoral neck prostheses, and the short stems prostheses. Between 1999–2004 more than 500 short stems prostheses (Mayoä) were implanted at the Orthopaedic department of the Martin-Luther-University, Halle, Germany. To investigate the early functional results, a prospective randomized study was performed comparing 40 cementless short stem prostheses (Mayoä 1) with 40 cementless anatomical standard stem prostheses (ABGä 2) implanted in patients with unilateral hip osteoarthritis. Age, gender, diagnoses, and body mass index showed no significant difference between both groups. In all patients, an uncemented acetabular press-fit cup was used. The implantations were performed by 4 orthopaedic consultants. A standardized anterolateral approach to the hip was used in all cases. In the short stem group, the femoral neck was preserved to achieve a multi-point fixation of the double-tapered stem in the intertrochanteric region. The patients were followed clinically and radiographically at 3, 6, and 12 months postoperatively. Differences between both groups were tested using Student’s t-test. No specific complications occurred neither during surgery nor during the follow-up (FU). No patient was lost for FU. The radiograhic FU showed a correct implant position in all cases. Concerning the Harris hip score (HHS), a statistically significant difference (< 0.01) was found at 3 months: the HHS for the short stem group averaged 93.87 points (range, 60–100 points), for the ABG group 87.02 points (range, 60–100 points). Preoperatively, at 6, and at 12 months, no statistically significant difference could be found between both groups. In this study, patients having a short stem prosthesis returned faster to work and normal daily activities. We attribute this to the femoral neck approach without involvement of the greater trochanter and the abductor muscles. With its good functional results and its bone-saving concept, the short stem is an attractive design particularly for young patients

Over the past 10 years, the orthopedic community has witnessed an increased interest in more conservative surgical techniques for hip arthroplasty. During this time, second-generation hip resurfacing and minimally invasive surgery enjoyed extensive marketing attention. After a decade of this renewed interest, both of these methods have met with serious concerns. As hip resurfacing numbers decline, both patients and surgeons are looking for other potentially successful conservative treatments to THA. This search has focused surgeon interest toward short-stem designs. Today, a variety of short-stem implants are available with very little clarification of design rationale, fixation features, surgical technique, and clinical outcomes. Virtually every major implant company now offers a “short stem,” and now there are a plethora of different designs. It is important to note, however, that not all short stems achieve initial fixation at the same bone interface region. Furthermore, surgical techniques vary greatly, and postoperative radiographic interpretation of short-stem position and fixation need to be carefully scrutinized. The purpose of this paper is to review past, present, and potential future developments of short femoral stems and to present a classification system that can offer guidance when reporting on the many different stem variations. Short Curved neck-sparing stem (JISRF classification 2a). Recently, new designs are following Pipino's Biodynamic stem style of saving the femoral neck. These designs feature a short curved stem that finds its stabilization contact region in the femoral neck and saves considerable bone in the medial calcar region. In addition, the curvature of the stem prevents violation of the lateral trochanteric region. The shorter stem also reduces blood loss by not reaming the femoral canal distally. These style stems generally have a variable stem length between 90 and 135 mm. This might not appear much shorter than conventional cementless stems (110 to 150 mm). However, the shorter curved neck sparing stems penetrate on average 1 to 2 cm less distally in the femoral canal. Short stems have a definite role in modern THA, as greater emphasis is being placed on soft tissue and bone sparing techniques and as refinements continue in the understanding of proximal femoral fixation. Metaphyseal short stems have significantly less surface contact area compared with conventional length stems and as a result, they might have less torsional and axial resistance. Neck-retaining short stems provide additional axial and torsional stability and reduced stress at the implant– bone interface and may be a consideration in the more active patient profile. Bone quality and the patient's physical activity should be considered prior to the selection of short-stem devices. Many short-stem designs have considerably different style features that may alter bone remodeling. Knowing the design and the required technique is vital to fit the device properly to the patient. The variations of short stems available call for caution in their overall use until there is better understanding of how dependent these stems are on individual stem features, bone quality, and surgical techniques. Overall, the authors are cautiously optimistic and continue advocating their selective use

Aims. The incidence of thigh pain with the short stem varies widely across different studies. We aimed to evaluate the incidence and characteristics of post-operative thigh pain after using a particular bladed short stem and its potential risk factors. Patients and Methods. We respectively reviewed 199 consecutive patients who underwent unilateral total hip replacement using the Tri-lock stem from 2013–2016, of which 168 patients were successfully followed up with minimum two year clinical follow-up. All information about thigh pain and pre- and postoperative HHS score were gathered and all preoperative and immediate postoperative radiographs were available for review. Any complications were recorded. Results. Of the 168 patients, 34 (20.2%) patients reported thigh pain at a mean 3.1 years after surgery. Of these, 2 (5.9%) reported severe pain (NRS 5 or more). The pain was persistent (from surgery to final follow-up) in 13 patients (38.2%) and subsided within 2 years in 10 cases (29.4%). The most common site of pain was the lateral thigh (70.6%). The HHS improved from a mean 54.2 points preoperatively to 79.8 postoperatively. In 123 cases with radiographs at more than 2 years follow-up, all femoral stems were well-fixed and no revision surgery was needed at the latest. BMI and CFI were found to be independent risk factors for thigh pain after using this particular stem component. Conclusions. The incidence of thigh pain in Chinese THA patients with a bladed short stem component design is as high as 20%. Among them, nearly 40% will have some disruption in sleep or daily life. More than one-third of the cases of thigh pain were persistent. A larger BMI and patients with a funnel-type morphology of the femoral canal are independent risk factors for thigh pain in the setting of this particular stem component

Background. The short stem prosthesis showed good results in patients with primary osteoarthritis. However, there were a few studies about the short stem THA in patients with osteonecrosis of the femoral head (ONFH). Objective. To evaluate the clinical and radiographic results of the short stem THA in patients with ONFH. The authors hypothesized that the short stem THA would be a promising procedure for patients with ONFH. Material and Method. The authors reviewed 120 osteonecrotic hips in 93 patients who underwent THA with Metha® short stem from November 2010 to February 2013. The appearance of bone trabeculae development and radiolucent line was reviewed using Gruen's classification. The Harris hip score (HHS) was recorded at 6, 12, 24 and 36 months postoperative for evaluating the clinical results. Results. The mean age of patients was 44.4 years (18–68) with the mean BMI of 22.7 (15.1–32.5, SD 3.5). The average follow-up period was 29.2 months (20–47). The mean HHS was significantly improved from 43.9 (22.7–74, SD 7.7) preoperatively to 97.7 (85.9–100, SD 2.7) at 6 months postoperatively (p<0.01). The radiographic change around the stems showed bone trabeculae development at zone 1 (77 cases)(64.2%), 2 (27 cases)(22.5%), 3 (106 cases)(88.3%), 6 (120 cases)(100%) and 7 (115 cases)(95.8%). There was 1 case (0.8%) of 5 mm subsidence and the radiolucent line was observed in zone 1. There were 6 cases (5%) of intraoperative femoral fractures and were treated with cerclage wires, no further subsidence was observed. There was 1 case (0.8%) of distal stem perforation which had stable bone ingrowth. No revision was required. Conclusion. The clinical and radiographic results of the short stem THA in patients with ONFH are generally satisfactory. Its design enables preservation of the bone stock and the bone trabeculae appear to confirm the assumption of proximal force transmission. The authors believe that the short stem THA is a promising procedure for patients with ONFH

Short stems are an option for primary THR, but these are the technical challenges. Stem anteversion is increased with short stems usually above 20 degrees so cup anteversion must be adjusted lower. Offset is better if increased up to 5 mm more because more bony neck is retained and with increased stem anteversion the greater trochanter is more posterior, and both of these increase the risk of bony impingement. Short stems are best in A bone, okay in B bone, not recommended yet in C bone. With standard stems performing so well use caution for conversion to short stems

An increasing use of short stem femoral components (SSA), in favour of conventional or “shaft” stems in THA has been reported. SSA components have been reported as bone conserving. Shaft stems are a proven and accepted form of treatment. FEA studies predict more physiological loading of bone with SSA. Cadaver femur studies demonstrate adequate stability for bone ingrowth, more physiological loading of the femur and reduced stress shielding with SSA. Clinical studies report improved outcomes with SSA compared to shaft stems (reduced bone loss, reduced pain, reduced intra-operative complication rate, improved early rehabilitation times and reduced overall cost). A mechanical analysis, to examine the reported improved outcomes with short stems and a rationale for the use of short stems rather than shaft stems is considered

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

An increasing demand for less traumatic THA combined with a faster recovery time has led to minimal invasive surgical approaches and to bone and soft tissue preserving short stem prostheses. Short stem prosthesis should have metaphyseal fixation, primary stability and lesser changes in femoral elasticity which would lead to less stress shielding. The need for a good joint stability and a higher mobility after THA has led to navigated hip surgery together with the use of modular necks to restore the biomechanics. From November 2004 to July 2008 we implanted 154 Metha prostheses by a modified less invasive Watson-Jones approach. 104 THA were navigated. The indication was primary (32%) or dysplastic coxarthritis (50%) or femoral head necrosis (18%) without affection of the femoral neck, patients age under 50 years and above with good bone density. Evaluation was done with regard to primary stability, ease of minimal invasive implantation and restoration of the biomechanics. The cup position was aimed at 45° of inclination and 15° of anteversion. The most used modular neck adapter in the non navigated group was standard (135°CCD, 0° antetorsion). In the navigated group more often different variations of neck adapters were used (mainly 135°CCD, 7.5° retrotorsion). Reliable length (+7mm overall) and offset (−3.5mm) measurements could be achieved in the navigated group. The average antetorsion of the stem was 20°. Bone loss is low with short stem and it is suitable for minimal invasive procedures. A good primary stability seems to be achievable. Modularity leads to a better restoration of the hip biomechanics. In the navigation of the short stem prosthesis the placement of the stem is separated from the restoration of the biomechanics of the hip. The criteria offset, leg length antetorsion, and center of rotation of the head and implant range of motion can be controlled for restoration by navigation. No dislocation was seen in the intraoperative test and in the postoperative follow up. The short term results show good functional result and a low complication rate without any dislocation. The use of a lesser invasive approach without detaching muscle led to a subjectively faster recovery. The navigation system helps to be precise in cup positioning and to restore biomechanics in term of center of rotation, leg length and offset by advising the best fitting modular neck and reliably predicting the safe range of motion. In our experience the navigated short stem prosthesis offered a good intraoperative handling and good preliminary results

Introduction. The use of short stems has been growing in THA for the past five years. As a result, a large number of short stem designs are available in the market place. However, fixation points differ for many of the designs resulting in different radiographic modeling creating confusion when trying to collate to clinical findings. We have created a classification system in an attempted to provide clarity in analyzing radiographic and clinical findings. Method. Femoral implants described as “short stems” were evaluated. The range of lengths for stem type and the method of achieving initial implant stability was determined. The optimal radiographic position of each of these implants and type of bone remodeling associated with this placement was evaluated. Stems were defined as “short” if the tip reached or was proximal to the metaphyseal-diaphyseal junction. This location on the proximal femur was defined as the place at which the medial-lateral metaphyseal flare became parallel. Stems were then classified as: 1.) Metaphyseal Stabilized; 2.) Neck Stabilized; 3.) Head Stabilized. An analysis of radiographic with a minimum of one year follow up were reviewed and posted as to the classification system. Results. The range of stem lengths for stem type and the method of achieving initial implant stability was determined. A classification of short-stemmed components has been defined, making it possible to evaluate and differentiate both radiographic and clinical findings. Not all so-called short stems exhibit the same radiographic and clinical findings. It also became apparent that the different stabilization points require specific surgical techniques to ensure reproducible good results. Findings for neck stabilized present with different findings as compared to metaphyseal stabilized and head stabilized. We are optimistic that this classification system will help to compare short-stemmed implants and how they performed to the more traditional convention cementless stems

Background. Thigh pain following a well-fixed total hip arthroplasty (THA) remains problematic and a source of patient dissatisfaction. The purpose of this study is to evaluate if the development of distal femoral cortical hypertrophy (DFCH) is associated with chronic postoperative thigh pain after THA with a short stem implant. Methods. All patients who underwent an uncomplicated primary THA via a direct anterior approach with the short stem Taperloc Microplasty® (Zimmer Biomet, Warsaw, IN) implant between 2011 and 2015 were mailed a pain drawing questionnaire. Radiographs were reviewed at 1-year minimum to determine cortical thickness change from immediate post-op. Thigh pain was compared to DFCH as well as patient demographics and femoral stem size. 293 patients were included in the study. Results. Mean follow-up was 3.2 years. A total of 218 hips (74%) had cortical hypertrophy in Gruen zone 3 and 165 hips (56%) had cortical hypertrophy in Gruen zone 5. Fifty-two hips (18%) had ≥25% cortical hypertrophy in zone 3 and 91 hips (31%) had ≥25% cortical hypertrophy in zone 5. A total of 44 patients (15%) reported anterior thigh pain and 43 patients (15%) reported lateral thigh pain. Development of DFCH in either Gruen zone 3 or 5 was not associated with anterior or lateral thigh pain. Stem size was positively correlated with zone 3 hypertrophy and inversely related to zone 5 hypertrophy. Thigh pain was not associated with patient age, gender, activity level or stem size. Conclusion. The development of distal femoral cortical hypertrophy after THA with a short stem implant was high, but not associated with patient reported anterior or lateral thigh pain. For any tables or figures, please contact the authors directly

Aims. The Mathys Affinis Short is the most frequently used stemless total shoulder prosthesis in the UK. The purpose of this prospective cohort study is to report the survivorship, clinical, and radiological outcomes of the first independent series of the Affinis Short prosthesis. Methods. From January 2011 to January 2019, a total of 141 Affinis Short prostheses were implanted in 127 patients by a single surgeon. Mean age at time of surgery was 68 (44 to 89). Minimum one year and maximum eight year follow-up (mean 3.7 years) was analyzed using the Oxford Shoulder Score (OSS) at latest follow-up. Kaplan-Meier survivorship analysis was performed with implant revision as the endpoint. Most recently performed radiographs were reviewed for component radiolucent lines (RLLs) and proximal humeral migration. Results. Five shoulders underwent revision surgery (3.5%); three for rotator cuff failure, one for infection, and one for component malposition. Survivorship of the implant was 95.4% (95% confidence interval 90.1% to 97.9%) at five and nine years. Mean OSS improved significantly compared to preoperative values from 19.0 (1 to 35) to 43.3 (7 to 48) (p < 0.001). Radiological analysis was undertaken for 99 shoulders. This revealed humeral RLLs in one case (1%), glenoid RLLs in 15 cases (15.2%), and radiological rotator cuff failure in 22 cases (22.2%). Conclusion. This prospective cohort study shows encouraging short- to mid-term survivorship and clinical and radiological results for the Mathys Affinis Short, Short Stem Total Shoulder Prosthesis. Level of Evidence: IV. Cite this article: Bone Jt Open 2021;2(1):58–65

As an increasing number of young, active, large patients are becoming candidates for total hip replacements, there is an increasingly urgent need to identify arthroplasties that will be durable, highly functional and amenable to possible future successful revision. In an era when cemented femoral stems were the primary implant option, the concept of a surface replacement was attractive and, perhaps, appropriate. However, cementless femoral stems of many designs now provide dependable long-term fixation and excellent, near normal function in patients of all ages, sex and level of activity. However, a number of issues related to cementless stem fixation could be further improved: Optimization of load transfer to proximal femur to minimise fracture risk and maximise bone preservation; Elimination of proximal-distal mismatch concerns, including bowed femurs; Facilitation of femoral stem insertion, especially with MIS THA exposures; Facilitation of revision with implants capable of providing durable fixation for active patients. The potential benefits of short stem femoral THA implants include: Ease of insertion; Reproducibility of insertion; Avoidance of issues related to proximal-distal anatomic mismatch or variations in proximal femoral diaphyseal anatomy (e.g. femoral bowing); Facilitation of MIS surgical approaches, especially anterior exposures; Optimization of proximal femoral load transfer with consequent maximization of proximal bone preservation. The purpose of this presentation is to describe the design rationale and characteristics of short (<115mm) uncemented primary THA femoral stem, to evaluate the clinical and radiographic results of short stems and to discuss the possible drawbacks specific to the use of short stems

Cementless femoral stems of many designs now provide dependable long-term fixation and excellent, near normal function in patients of all ages, sexes and level of activity. However, a number of issues related to cementless stem fixation could be further improved: Optimization of load transfer to proximal femur to minimise fracture risk and maximise bone preservation; Elimination of proximal-distal mismatch concerns, including bowed femurs; Facilitation of femoral stem insertion, especially for Anterior and MIS exposures; Facilitation of revision with implants capable of providing durable fixation for active patients. The potential benefits of short stem femoral THA implants include: Ease of insertion; Reproducibility of insertion; Avoidance of issues related to proximal-distal anatomic mismatch or variations in proximal femoral diaphyseal anatomy (e.g. femoral bowing); Facilitation of MIS surgical approaches, especially anterior exposures; Optimization of proximal femoral load transfer with consequent maximization of proximal bone preservation. The purpose of this presentation is to describe the design rationale and characteristics of short (< 120 mm) uncemented primary THA femoral stems and to evaluate the clinical and radiographic results of short stems. Outcome results extending beyond 10 years support the proposition that short stems of appropriate design provide dependable long-term fixation and equivalent clinical results to those currently achievable with cementless stems of conventional length in patients of all ages, sexes and level of activity

As an increasing number of young, active, large patients are becoming candidates for total hip replacements, there is an increasingly urgent need to identify arthroplasties that will be durable, highly functional and amenable to possible future successful revision. In an era when cemented femoral stems were the primary implant option, the concept of a surface replacement was attractive and, perhaps, appropriate. However, cementless femoral stems of many designs now provide dependable long-term fixation and excellent, near normal function in patients of all ages, sex and level of activity. However, a number of issues related to cementless stem fixation could be further improved: Optimisation of load transfer to proximal femur to minimise fracture risk and maximise bone preservation; Elimination of proximal-distal mismatch concerns, including bowed femurs; Facilitation of femoral stem insertion, especially with MIS THA exposures; Facilitation of revision with implants capable of providing durable fixation for active patients. The potential benefits of short stem femoral THA implants include: Ease of insertion; Reproducibility of insertion; Avoidance of issues related to proximal-distal anatomic mismatch or variations in proximal femoral diaphyseal anatomy (e.g. femoral bowing); Facilitation of MIS surgical approaches, especially anterior exposures; Optimisation of proximal femoral load transfer with consequent maximisation of proximal bone preservation. The purpose of this presentation is to describe the design rationale and characteristics of short (< 115mm) uncemented primary THA femoral stem, to evaluate the clinical and radiographic results of short stems and to discuss the possible drawbacks specific to the use of short stems

Introduction. The concept of neck preserving stems, known as short femoral stems or metaphyseal stems has been utilized to improve the outcomes of standard cementless stems. The preservation of the proximal femoral bone stock results in decreasing the potential stress shielding and thigh pain. Additionally, these stems may be used in less invasive procedures and provide the option for easier revision procedures if implant failure occurs. In this study we aim to demonstrate the clinical outcome of direct anterior approach of total hip arthroplasty (THA) with short stem prosthesis. Methods. In this study, 390 total cases of THA in 345 patients who underwent an anterior approach of THA by using a new type of short-stem prosthesis (Minihip, Corin) between 2009 and 2013 were reviewed. There were 282 male and 62 female patients and Table 1 summarizes the demographics. In 48 cases avascular necrosis (AVN) was the diagnosis and 339 cases were reported to be due to osteoarthritis. Twenty eight patients were assessed to have American Society of Anesthesiologist (ASA) physical functional score of class I, 258 patients had class II, 103 had class III, and 1 had class IV. Table 2 shows the Charnley classification of the patients. In the current study we evaluated the outcomes of the surgery by utilizing Hip Disability and Osteoarthritis Outcome Score (HOOS) subscales (Pain, Symptoms, Function in daily living (ADL), Function in sport and recreation (Sport) and hip related Quality of life (QOL)). Results. All HOOS subscores were significantly increased from preoperative assessments (F (5,97) = 1679, p < 0.001). The outcome are summarized in Table 4 and Figure 1. No failure of the implant has yet been reported however in 9 cases (2%) calcar fracture occurred during the surgery that were successfully treated with cerclage wires. While no implant loosening was observed, there were four cases (1%) with asymptomatic subsidence (≥ 2mm). Conclusion and Discussion. This study continues to support the excellent clinical outcomes of this short-stem prosthesis when is used for primary total hip arthroplasty. Based on the current findings, we expect that this short stem implant is an excellent choice particularly for younger individuals

The charateristic of Brexis short stem are:. -Minimal bone loss. -Physiologic load transmission. -Solid anchorage. -Biocompatibility and osteointegration. -Polished brilliant in use

Introduction. Dysplastic hip has not only deficiency of acetabulum but also femoral deformity. Therefore, selection of stem is important in cementless THA for dysplasia. Especially using of short stem should be challenge for deformed femur. We studied clinical performance and radiological findings after THA with triple tapered short stem (Optimys hip) for dysplastic hip. Materials and method. From May 2013, we performed cementless THA for osteoarthritis with dysplasia. Seventy-one hips of 67 patients were examined including four males and 63 females. Age at surgery was from 36 to 88 years old (61.7 in average). Surgical approach was used modified Watson-Jones in all hips. Clinical evaluation was used modified Harris hip score (MHSS), incidence of complications and thig pain. Radiological findings were evaluated according Engh's classification and grade of stress shielding. Follow-up period was minimum one year and was 21.3 months in average. Results. MHHS before surgery was 41 points and that at follow-up was 88 points in average and pain score was significantly improved. Calcar fracture during surgery occurred in two hips and circular wiring was performed. Deep infection, DVT and dislocation were not observed. Incidence of thigh pain was 1.4% of one hip. Radiological findings were assessed as bone in-grown in all of the hips and grade of stress-shielding was very low. There were no aseptic loosening and no revision for any reasons. Conclusions. Cementless THA with triple tapered short stem was useful for treatment of dysplastic hips. Radiological findings of all hip were assessed as bone in-grown

Recent introduction of short femoral implants has produced inconsistent outcomes. There have been reports of early aseptic failure as high as 30% within 2 years of implantation. This is in spite of the fact that these short components are shortened versions of existing successful non-cemented designs. The mode of initial fixation in non-cemented implants has been investigated. It has been demonstrated that long term survivability is dependent upon osseous integration; and that osseous integration requires secure initial implant fixation. Traditional non-cemented implants achieve initial fixation analogous to that of a nail in a piece of wood: friction and displacement (with resultant hoop stress). Initial fixation, of a traditional non-cemented femoral component, is directly proportional to surface area contact between the implant and endosteal bone and/or three point fixation. By reducing stem length, contact area may be significantly reduced, thereby increasing stresses over a smaller area of contact. The result of this is to potentially compromise fixation/implant stability against micromotion occurring in the early post-operative period. These stresses are most poorly resisted in flexion/extension and rotational planes about the long axis of the femur. In addition, force applied in an attempt to achieve initial fixation with a short stem may lead to an increased risk of periprosthetic fracture at the time of implantation. We propose that there is an alternative mode of initial fixation, a “rest fit”, that may avoid both the risk of femoral fracture as well as provide better initial implant stability. To assure a maximal initial fixation and resistance to post-operative stresses which may compromise initial implant stability and osseous integration, a short implant should have three distinct geometric features: a medial and lateral flare, a flat posterior surface and a proximal trapezoidal cross section. The first will provide stability against subsidence and varus migration, by resting upon the proximal femur. A flat posterior surface will maximize load transmission to the femur in flexon/extension activities; and an asymmetrical proximal cross-section will provide resistance against rotational stresses about the long axis of the femur during activities such as stairclimbing. Together these features have been throproughly evaluated by FEA and in vitro testing. We are reporting on the shoprt term follow up (2.5 years avg.) first 300 short stems which have employed a “rest fit”. There have been no aseptic failures or revisions for mechanical failure of these implants

Introduction. Most Japanese patients who receive total hip arthroplasty (THA) are osteoarthritic and 70% have development dysplasia of the hip. Their stature is shorter than average and their sizes (acetabular cup and femoral stem) are smaller. The Taperloc Microplasty (BIOMET) is a short femoral stem. It was launched on July 2012 in Japan (extended on January 2013). It is essentially a shortened version of the Taperloc stem (35mm shorter than the standard stem). Objectives. We aimed to evaluate the outcomes of minimally invasive anterolateral THA using a short stem. Methods. We retrospectively reviewed all 56 patients who underwent THA at our hospitals between July 2013 and April 2015. Of these 28 (50%) were performed with short stems. The surgical approach was antero-lateral in the lateral position. The patients (4 men and 24 women) had a mean age at surgery of 66.5 years (range, 46–85 years). The original diseases were osteoarthritis (25 patients) and osteonecrosis (3 patients). We investigated the system type, size (cup, femoral head, and stem), radiological findings and complications (fracture, infection, deep vein thrombosis, and dislocation). Results. There were no severe complications, such as, infection, deep vein thrombosis, or dislocation. One patient had a femur fracture during operation and was switched to a standard stem. The mean surgery duration was 102 minutes (range, 80–142 minutes) and the mean amount of bleeding during surgery was 254 g (range, 95–720 g). Mean cup size was 51.0 mm (range, 48–60 mm) and stem size is 6 (range, 4–13). Radiological findings showed 2 patients had stem subsidence (within 5mm). One of them had severe osteoporosis and the other patient had leg length discrepancy. Conclusions. Minimally invasive anterolateral THA using a short femoral stem has good clinical and radiological results in Japanese patients. Long-term results should be further observed prospectively

While short stem designs are not a new concept, interest has surged with increasing popularity of less invasive techniques. If the goal of the tapered stem is to load preferentially proximally, why do we need a stem at all? Perhaps the only reason to use a tapered, long stem is to prevent varus; however, studies have shown that varus malalignment of a tapered stem does not affect results. Short stems are easier to insert, especially when using an anterior approach such as the anterior supine intermuscular in which the proximal femur is elevated anteriorly from the wound during stem insertion. Femoral preparation can be accomplished with straightforward broaching of the canal, without use of reamers. Short stems are bone conserving. They violate less femoral bone stock, providing more favorable conditions should a revision be required. However, ease of insertion and bone conservation matter little if not supported by clinical results. Thus, we reviewed our early experience with 2094 patients undergoing 2457 primary THA using short, tapered titanium, porous plasma spray-coated femoral components since January 2006 at our center. The TaperLoc Microplasty stem (Biomet, Warsaw, IN) has been used in 1881 THA, and the TaperLoc Complete Microplasty stem (Biomet) in 576. Patient age averaged 63.6 years. Increased offset was used in 1990 hips (81%). The surgical approach was less invasive direct lateral (LIDL) in 1194 THA (49%), anterior supine intermuscular (ASI) in 1117 (46%), and standard direct lateral (Std) in 146 (6%). Follow-up averaged 20 months. Thirty-five stems (1.4%) have been revised: 15 for infection (12 LIDL, 3 ASI), 1 same day revision for intraoperative femoral shaft perforation (Std), 1 at 3 days for patellar dislocation (LIDL), 2 for early subsidence (1 LIDL, 1 ASI), 13 for periprosthetic femoral fracture (1 Std, 12 ASI), 2 for aseptic loosening (1 LIDL, 1 ASI), and 1 stem well fixed (ASI) removed for loose cup and unable to disarticulate trunnion. What lessons have we learned? First, we usually require one or two diameter sizes larger with short porous tapered stem versus the standard length version of the same design. The surgeon should be aggressive with sizing, pushing to the largest size possible. Use the broach like a rasp. Drive the component in valgus during insertion. Upon seating the component, do a trial reduction using the shortest available neck length. The component will generally sit slightly prouder than the broach and may require additional effort to seat completely. Conservation of existing bone stock, compatibility with soft-tissue sparing surgery, more physiologic loading of the proximal femur, and versatility with varying femoral anatomy make the short taper an attractive implant option. The tapered wedge short stem represents the natural evolution of joint arthroplasty to a smaller, less-invasive, and more efficient implant

Introduction. We have been developed lateral flare stem and have been using it since 1989. It was custom stem at first. After being experienced, using the same software, off-the-shelf version lateral flare stem (Revelation) was developed in 1996 in the U.S. We could start using it since 2001 in our country. Lateral flare stems are designed to reproduce physiological proximal load transfer lateral side as well as medial side. It was obtained by having bigger and more accurate proximal part with lateral flare. The design is optimized by matching with 3D insertion path. Using many custom stems including different length and off-the-shelf standard stems, we have come to feel that as for this high proximal fit and load transfer design, it is not necessary to having long distal part and sometimes it is harmful to obtain good proximal load transfer in some situation such as type A (champagne flute) canal. So we have developed short version of the stem. Many makes of the hip stems have included short stems recently. Some aimed to improve easier insertion, some aimed to improve the volume of residual bone quantity. We have aimed to improve proximal fit expecting more proximal and more physiological load transfer to the femur. Objectives. Our objectives are to comare standard stem and short stem from biomechanical aspect and clinical aspect. Materials and methods. As for the biomechanical aspect, finite element analyses were done with standard and short stem. As for the clinical aspect, the very last 25 cases of the standard stems; which we have 12 years clinical experience; done at Nagoya City University, the very first 25 cases of the short stems, and the next 25 cases were examined. The distance between stem and cortical bone on medial and lateral side at lateral flare hight of the stem and the bottom of arc deposite coated area. Alignment was assessed by the angle of the stem and canal axis. Result. By the FEA, small stress point was observed at the tip of the standard stem which pushes canal wall from inside (Fig. 1), which was disappeared at the tip of the short stem. Less micromotion was observed in short stem too. No significant difference was observed in the stem cortical distance. No significant difference of stem alignment was observed between standard stem and all 50 short stems but better alignment (p = 0.07) was seen in the second 25 cases of the short stem than standard stem. Between the first 25 and the second 25 case high difference (p = 0.01) was seen. (Fig. 2). Discussion. The standard lateral flare stem has very physiological proximal load transfer in most of the cases, sometimes longer distal part could effect to the alignment because of the femoral bending. Short stem could be expected have better alignment being free from femoral bending. On the contrary, distal part could be the insertion guide during the surgery. For the short stem, learning curve exists to realize potentially better alignment

Background. Short stem has potential advantages of bone and muscle preservation. Current papers demonstrate that direct anterior approach (DAA) is a significant minimally invasive muscle-sparing approach to total hip arthroplasty. Theoretically, a short length stem with a reduced lateral shoulder is the most appropriate design for DAA. Objectives. To clarify the necessity of the standard length stem in tapered-wedge stem. Patients and methods. We prepared two kinds of tapered-wedge stem, Taperloc (standard length stem) and Microplasty (short stem) (Biomet, warsaw, Indiana) at the surgery. If the rasp for the short stem had not been fixed rigidly intra-operatively, it would have been changed to the standard length stem. Between May in 2010 and April in 2011, 94 patients (107 hips, 13 bilateral) were included in this study. All THAs were performed by direct anterior approach (DAA) on a standard surgical table. We analyzed the early clinical and radiographic results of 107 THAs in 94 patients (60 women, 34 men). The mean age was 61 (33∼84) years. The mean height was 161 (142∼182) cm and the mean weight was 63 (40∼92) kg. Results. All hips were implanted with the short stem. There was no need of the standard length stem. The mean operative time was 54 (28–140) minutes and the mean operative blood loss was 422 (60∼2400) ml. There was a significant improvement in functional outcome of these patients as measured by Japanese Orthopedic association hip scores. There were three complications intra-operatively or post-operatively. These were one intraoperative femoral fracture which was salvaged with circular wiring, one femoral fatigue fracture which occurred 6 weeks and cured conservatively, and one pulmonary embolism. There were no stem subsidence, dislocations and infections. Conclusion. This study confirms that there is no need of a standard length stem in THA using tapered-wedge stem. The short stem and DAA would be a winning combination for THA

Although many distal fit and fill design cementless stems have shown a very good long term stable fixation, short proximal coated stems are recently increasing in their use with an expectation of less stress shielding and an ease of removal at revision surgery. We introduced an anatomic short stem made from titanium alloy with proximal plasma-spray titanium and hydroxyapatite coating (CentPillar, Stryker, Mahwah) in 2002. To evaluate a minimum 10-year outcome of the system in terms of fixation and stress shielding, we reviewed initial 100 consecutive cases operated by a single surgeon. There were 91 hips with osteoarthritis and 9 hips with osteonecrosis. There were 94 females and 6 males. Average age at operation was 58 years. The patients were followed up for an average of 11 years. Average JOA hip score improved significantly from 46.9 preoperatively to 96.7 at the final examination. There were no dislocation, or revision, or radiographic loosening. When we looked at the level of bone atrophy, 80% of cases showed no stress shielding below the lessor trochanter. We conclude that the CentPillar stem showed mild stress shielding due to short proximal bone ongrowth coating while keeping a long term good clinical score and radiographic stability

Accurate glenoid component placement continues to be a challenge. Knowledge that glenoid loosening is affected by malpositioning of the glenoid component has led to the development of patient specific instrumentation (PSI) in an attempt to optimise glenoid positioning. The ideal PSI would be reusable, reliable, cost-effective and robust enough to tolerate the stresses applied by the surgeon in the context of difficult glenohumeral exposure. The VIP system is a CT scan-based PSI with a reusable instrument. The subtle nuances of pre-operative planning will be discussed in a separate short video. The live surgery will incorporate use of the patient specific instrumentation during glenoid placement and the use of a short stemmed fourth generation total shoulder arthroplasty

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

Femoral components used in total hip arthroplasty (THA) rely on good initial fixation determined by implant design, femoral morphology, and surgical technique. A higher rate of varus alignment may be of specific concern with short stem implants. Varus placement in uncemented femoral components has been proven not to be detrimental to clinical function; though long-term bone remodeling secondary to varus placement remains unknown. The goal of this study was to compare the clinical and radiographic outcomes in patients who underwent THA with one of two uncemented short stem metaphyseal engaging implants at minimum two-year follow-up. A review of 105 patients (average age 65 years; BMI 29 kg/m. 2. ) who underwent a total of 109 primary THAs using the ABG II short stem femoral implant (Stryker, Mahwah, NJ), and 160 hips in 149 patients (average age 70 years; BMI 28 kg/m. 2. ) who underwent primary THA using the Citation stem (Stryker, Mahwah, NJ). The same surgeon (SDS) performed all surgeries through a less invasive posterolateral approach. Pre-operative and post-operative Harris Hips Scores (HHS) and WOMAC scores were collected. Digital radiograph analysis was performed including measuring the stem alignment relative to the femoral shaft. A stem placed with greater than 5 degrees of varus was considered to be in varus. There was no significant difference in demographics (age, gender or BMI) or pre-operative HHS and WOMAC scores between the two groups. Follow-up HHS was 90 (range 63–100) and 94 (range 70–100) for the ABG II and Citation groups, respectively. Follow-up WOMAC scores were 10 (range 0–24) and 6 (range 0–43) for the ABG II and Citation groups, respectively. There was no statistically significant difference in any of the scores between the two groups (p>0.05). When looking at AP radiographs for postoperative intramedullary alignment, none of the ABG II implants were placed in varus (>5°), while a small number (4.9%) of Citation implants were implanted in varus alignment. No significant difference was observed in the alignment between the two groups (p>0.05). Average post-op alignment with the ABG was 1.10° (range −4.7–4.9°) and 0.88° (range −4.5–8.9°) with the Citation. The clinical results associated with the use of these stems in patients of all ages and bone types have been identical to those achieved by uncemented stems of standard length. Both implants in this study had excellent clinical and functional results in primary THA after a minimum 24-month follow up. In addition, postoperative radiographic analysis demonstrated that these stems can be reliably and reproducibly placed in neutral alignment despite their short length. The lateral flare on the Citation implant led to a greater number of implants in varus alignment, potentially affecting offset and leg-length, yet the relative increased incidence compared to the ABG II was not significant. Further research is needed in designing implants that optimize proximal femoral contact while maintaining alignment and overall hip kinematics

Introduction:. The robot-assisted cementless total hip arthroplasty has theoretical advantages of providing better fit and mechanical stability of the stem. However, no previous study has been reported on a short stem implantation using surgical robot. We compared early clinical and radiographic results between robotic milling and manual rasping in short stem total hip arthroplasty. Materials & Methods:. We designed a prospective randomized controlled trial to determine whether robot-assisted short stem total hip arthroplasty improves the implant position represented by stem alignment, leg length equality, and reduces the intraoperative and early postoperative complications. A total of 40 patients were enrolled with informed consents and randomly assigned to robotic milling group (20 hips) and manual rasping group (20 hips) by means of a computer-generated random number table. There were no statistically significant differences in the demographics of the patients between the two groups. Results:. Total operation time of the robotic milling group was significantly longer than that of the manual rasping group (p = 0.015) with average 8.8 minutes registration time and average 11.1 minutes milling time. There was no significantly difference in total blood loss between the two groups. The robotic milling group showed superior results on stem alignment and leg length equality compared with the manual rasping group. Only in the manual rasping group, there were 2 intraoperative femoral fractures. No complications such as infection, nerve palsy or dislocation encountered in both groups. Conclusions:. Robotic-assisted short stem total hip arthroplasty has advantages in increased accuracy of stem alignment and leg length equality, and also helps reduce the potential risk of intraoperative femoral fracture

The Mayo-Stem is short and tapered in the anteroposterior and mediolateral directions, designed to enhance early fixation through multiple point contact in the proximal medullary cavity. The purpose of this study was to investigate the clinical and radiographic results of total hip arthroplasty (THA) using this short stem in younger patients. A total of 97 cementless THAs using this short stem were investigated. The length of the stem used ranged from 90mm to 110 mm. The average age of the patients at the time of surgery was 50.9 years (33–64 years). The average follow-up period was 64 months (38–108 months). The Harris hip score was used for clinical evaluation. The valgus angles of the stems and the changes in radiographic findings around the stems after surgery were investigated on the AP radiographs of hip. The average Harris hip score was 52.0 points pre-operatively and 93.9 points at the latest follow-up. An intraoperative femoral fissure fracture of the proximal femur occurred in 15 hips (15.4%), which were treated by circlage wires. The average valgus angle of the stem was 3.5° (range: −6°–18°). The development of bone trabeculae was seen around the curve of the stem (Gruen zones 3 and 5) in 79.4 % of hips one year after surgery. A radiolucent line was found on the lateral side of the stem (Gruen zones 1, 2, and 3) in 13.4 % of hips, which occurred in connection with the development of bone trabeculae. Subsidence of the stems (> 2mm) was seen in three hips in which intraoperative femoral fissure fracture had not occurred. These hips did not get the development of bone trabeculae. In two hips of the three hips, the valgus angles of the stems were 15° and 17° respectively. In the case of the third hip, the stem was small to the proximal femur. Overall the clinical result of THA using a short-stem was basically gratifying. The development of bone trabeculae, the stem size to the proximal femur and the stem position were important factors for the fixation of stem. Intraoperative fissure fracture treated by circlage wires and radiolucent lines with the development of bone trabeculae did not affect the fixation of stem

Introduction. Since 1989, we have been developing lateral flare stem. The concept of lateral flare stem is to deliver proximal part big enough to fill the proximal cavity that most of the cement stems can fill and most of the cementless stems cannot. Also having distal part polished, much less distal load transfer occurs than cement stem. Thus, we can expect high proximal load transfer to prevent stress shielding. To deliver lateral flare stem, straight insertion path cannot be available, as proximal lateral part to fill inside the greater throchanter collides to the greater trochanter. So 3-Dimension insertion path was calculated to deliver that part through the narrow made by neck osteotomy. The first generation of the lateral flare stem was custom made. The second generation was designed as an off-the-shelf stem from what we have learned by the experience of custom stems. With the third generation, the stem was shortened to achieve more proximal load transfer. Direct Anterior Approach (DAA) developed by Judet is one of less invasive hip approach. With a stem with straight insertion path, the extended line of proximal femoral axis should come out of the skin. To achieve this position, proximal end of the femur has to be fully pulled up. (Fig.1) Some of the cases would be able to be lifted up but some have difficulty. Using lateral flare stem with curved 3 dimensional insertion path, even the axis extension does not come out of the skin, it would be expected to be inserted. In the present study, 3D insertion path of the lateral flare short stem for DAA was analyzed. Materials and methods. Preoperative CAT scan data were transferred to STL data by Mimics®. The procedures after that were done by Magics®. First, neck osteotomy was done, externally rotated, and mild extension that doesn't make the axis come out of the skin was added. Then insertion path was verified keeping the stem attached medial sidewall of the canal (Fig. 2). In actual case, skin translation and pelvis rotation was assessed by 3D scanner. (Fig. 3). Results. Three D scanner revealed that the pelvis rotation is less than detective limit, and the upper skin incision where the stem passes remains almost the same place by dropping the leg. Lateral flare short stem could be inserted without lifting the femur out of the skin. So it was expected that lateral flare short stem has high applicability for DAA. Discussion. We can expect less invasive THA with DAA. However, once we have problem during surgery such as hard insertion or fracture and so forth, it is very hard to recover from those difficulties, because with supine position we cannot access posterior side of the leg. By easier insertion, less stress for bone and other tissues, we can reduce the risks. Even cases with easier femoral lift up, pulling femur less can reduce those risks

Recent trends in surgical techniques for THR, i.e. MIS and anterior approaches, have spawned an interest in and possible need for shorter femoral prostheses. Although, early clinical investigations with custom short stems have reported very encouraging results, the transition to off-the-shelf (OTS) versions of shorter length prostheses has not met with the same degree of success. Early reports with OTS devices have documented unacceptably high and significant incidences of implant instability, migration, mechanical/aseptic failure, and technical difficulty in achieving reproducible implantation outcomes. They have highlighted the absolute need for a better understanding of the consequences of changes in implant design as well as for improvements in instrumentation and surgeon training. Two basic questions must be addressed. First, what is the purpose of a stem? And second, can stem length be reduced and if so by how much can this be safely done. What are the effects of stem shortening and are there other design criteria which must take on greater importance in the absence of a stem to protect against implant failure. To examine these questions a testing rig was constructed which attempts to simulate the in vivo loading situation of a hip, fig. 1. Fresh cadaveric femora were tested with the femora intact and then with femoral components of varying stem length implanted to examine the distribution of stresses within the femur under increasing loads as a function of stem length. Our studies indicated that a stem is not an absolute requirement in order to achieve a well functioning, stable implant. However in order to reduce the possibility of mechanical failure a reduced stem or stemless implant absolutely must have three important characteristics to its design. First, it must have sufficient medial/lateral dimension to provide stability against subsidence and varus stress; second it must have a flat posterior surface, parallel and in contact with the posterior endosteal surface of the proximal femur with which to maximize A/P stability against flexion/extension forces (As a consequence of this design feature, appropriate anteversion must be achieved in the neck region of the prosthesis and not by rotation of the implant within the proximal metaphyseal cavity of the femur); and third, the implant must also have a cross-sectional geometry that will stabilize against torsional loading about the long axis of the femur. Therefore, simply reducing the length of an existing implant to accommodate changes in surgical techniques may not be a reasonable or safe design change. Such shortened versions of existing stem designs must be rigorously tested before being released for general use. The required design parameters outlined above have been clinically validated in custom fabricated implants. They have been shown to reduce aseptic loosening and migration of a short stem femoral implant. This report will provide the clinical review of a multi-center experience with the first 200 off-the-shelf “Lateral Flare” short stem implants

Introduction:. Significant proximal femoral remodeling occurs after total hip arthroplasty (THA), with regions of bone loss, and regions of hypertrophy. This study compared three implants for changes in femoral bone mineral density over 2 years following primary uncemented hip arthroplasty with a conventional stem (THA), a novel femoral neck-sparing short hip stem (NS-THA), and resurfacing hip arthroplasty (RHA). Methods:. Seventy-one patients participated in this non-randomized, prospective study. All patients had a diagnosis of osteoarthritis and underwent primary uncemented hip arthroplasty. Dual Energy XRay Absorptomitry (DXA) scans were performed at preoperative, 3–7 days post-op, 6 weeks, 6 months, one, and two years post-op. Using custom 2 cm zones, 19 zones were observed for percent changes in bone mineral density (BMD). Radiographs and Harris Hip scores were obtained at each visit. Results:. Age, gender, and BMI were found to be statistically different with fewer females and lower age in the RHA group, and a lower age in the NS-THA group. In all three groups, regions that were located proximally were shown to be the most susceptible to bone loss. Combined 2 cm zones 1C/7C, 2A/6A, and 2B/6B showed statistical significance (p < 0.05). Bone loss in the proximal regions was 8–10% lower with the femoral neck-sparing short stem, and least in the RHA group, causing little to no BMD loss in proximal regions. Radiographic outcomes and clinical results including Harris Hip scores were equal between the groups. Conclusion:. Consistent with our hypothesis, it was found that hip arthroplasty with a conventional stem resulted in the highest proximal femoral bone loss, and resurfacing arthroplasty was associated with the least bone loss. The femoral neck-sparing short stem ameliorated the bone loss seen with traditional hip arthroplasty, and approximated the bone preservation seen with hip resurfacing. The short stem neck-sparing device may provide some of the benefits of hip resurfacing, but could potentially have wider indications for use

Aim. The purpose of the study was to analyse short- and medium-term results of a modern cementless short stem design hip joint endoprosthesis together with different parameters (offset, CCD, leg length), radiological findings and scores. Material and Methods. 186 cases using a metaphyseal fixed short stem prosthesis (MiniHip, Corin) at two hospitals were included for clinical follow-up. 180 patients were available for clinical follow-up with standardized scores: Oxford-Hip Score (OHS), Hip Dysfunction an Osteoarthritis Outcome Score (HOOS) and EQ-5D – Score. The scores were caught preoperatively and postoperatively every year. Further on we could do a prospective radiological study of 250 consecutive hips with degenerative hip osteoarthritis were included (246 patients). These patients were operated by five different surgeons at 4 different hospitals. Standardized X-rays were performed with the same technique pre- and postoperatively in all patients. Different anatomical parameters of the hip were documented by using the pre- and postoperative x-rays (Offset, CCD angle, length of leg). The 250 patients included 129 female and 117 male. The average age of the patients was 59.7 years (range: 27–82 years). The whole follow-up and all measurements were performed by an independent examiner. Results. The Oxford Hip Score increased from a preoperative average of 17.63 to a postoperative average of 44.22 within the first year (180 hips). The postoperative average was 45.74 within the second (94 hips), and 46.20 within the third year (15 hips). The HOOS rose from a preoperative average of 29.91 to 96.20 (180 hips) within the first year. After two years the HOSS had an average of 94.30 (94 hips) and 95.72 (15 hips) after three years. The EQ-5D showed a postoperative average of 77.66 points for the 180 patients. At the time of the last follow-up two stems had aseptic loosening. The Offset only changed +0.29 cm (SD: 0.45 cm) after surgery. We could document only a small decrease of −0.51° (SD: 4.10°) of the CCD angle. The length of leg increased on average of +0.09 cm (SD: 0.34 cm). We found no difference between the measurements of female and male patients. Conclusion. Our results show, that we could reconstruct the individual geometry of the hip quite well by using the metaphysial short stem prosthesis. The tendency of an increasing CCD angle and a decrease of the offset seems not to be existent with the design of this kind of short stem prothesis

Fixation of the femoral component in total hip arthroplasty is a surgical challenge in the best of circumstances. Achieving immediate fixation without breaking the femur is a challenge, even to highly skilled and experienced arthroplasty surgeons. Surgical procedures are available that offer cosmetic benefit or a slightly quicker recovery, but accepting this compromise for fixation should be avoided. The mechanical environment of the femoral component is challenging. The implant is exposed to offset loading in two planes, which results in substantial bending stress and rotational loads in the frontal plane as well as bending stress and torsional loads in the sagittal plane. The proximal femur is built to transmit load through the surface fibers, not the central cavity, so efforts to change it to a centrally loaded structure are fraught with difficulty. The entire structure should be used. The least reliable material is the cancellous bone in the intertrochanteric metaphysis and the most effective is the cancellous bone of the femoral neck and cortical bone of the upper diaphysis. For best fixation of the femoral component, the cortical bone of the upper metaphysis should be contacted, and the diaphyseal cortical bone actually should be grooved by the femoral stem during insertion. Approach to the hip is important in fixation of the femoral component. Approaches that require femoral neck resection and use of a short stem are especially treacherous. The posterior approach is attractive because it encourages preservation of the femoral neck, and it provides straight access to the medullary canal of the femur while protecting the abductor muscles. Static axial load in the extended position is most readily resisted by the femoral component. Distal cortical contact is very important to prevent toggle. Torsional loads generated from offset loading of the femoral head in flexion and with front-to-back acceleration generated loads during rapid gait are the most challenging in securing fixation of the implant. Ideal conditions include preservation of the femoral neck, engagement of a rectangular stem in a rectangular cavity, and mechanical lock into grooves in the diaphyseal cortical bone. If all these conditions are met, femoral component fixation can be achieved every time without damaging the abductor muscle group, and with minimal danger of femoral fracture. A posterior approach with femoral neck preservation and a rectangular shaped femoral component with diaphyseal engaging stem is safe surgery and good mechanics. The anterior approach with femoral neck sacrifice and round, short stems is unsafe surgery and bad mechanics

Despite the clinical success of uncemented femoral stems of various types, current issues continue to require repeated examination:. proximal-distal mismatch. optimization of load transfer and preservation of femoral bone and. facilitation of MIS (minimally-invasive surgery) exposures, particularly an anterior approach. A previous study demonstrated that a custom-made (based on CT-scan) short metaphyseal engaging femoral stem design provided stable fixation and reliable bony ingrowth at four-year follow-up. The purpose of this study is to present the minimum two-year clinical and radiographic results obtained with an off-the-shelf metaphyseal filling stem. An uncemented, metaphyseal engaging femoral stem was inserted in 194 consecutive hips in 181 patients, whose average age was 70 years (range 32–95) and BMI of 28 (range 19–63). The implant, which averaged 94 millimeters in length (range 91–105), was made of titanium alloy with a hydroxyapatite coating on a titanium plasma-spray in the third of the stem. The average Harris hip score (HHS) was 52 (range 10–80) preoperatively and 91 (range 70–100) postoperatively and no patients experienced thigh pain. Preoperative WOMAC scores averaged 48, compared to a postoperative average of 4. There were no fractures or other complications related to the prosthesis, no radiographic evidence of subsidence, and all stems were radiographically stable on most recent radiographs. The typical pattern of bony ingrowth was that of bone bridging and endosteal condensation at the proximal portion of the stem. This study demonstrated that the use of an off-the-shelf short femoral stem designed to fit and fill the metaphysis provides reliable clinical and radiographic results at a minimum two-year (average 31 months) follow-up. Short stems may be particularly helpful to surgeons performing total hip arthroplasty using a MIS anterior approach

Recent trends in surgical techniques for THR, i.e. MIS and anterior approaches, have spawned an interest in and possible need for shorter femoral prostheses. Although, early clinical investigations with custom short stems have reported very encouraging results, the transition to off-the-shelf (OTS) versions of shorter length prostheses has not met with the same degree of success. Early reports with OTS devices have documented unacceptably high and significant incidences of implant instability, migration, mechanical/aseptic failure, and technical difficulty in achieving reproducible implantation outcomes. They have highlighted the absolute need for a better understanding of the consequences of changes in implant design as well as for improvements in instrumentation and surgeon training. Two basic questions must be addressed. First, what is the purpose of a stem? And second, can stem length be reduced and if so by how much can this be safely done. What are the effects of stem shortening and are there other design criteria which must take on greater importance in the absence of a stem to protect against implant failure. To examine these questions a testing rig was constructed which attempts to simulate the in vivo loading situation of a hip, fig. 1. Fresh cadaveric femora were tested with the femora intact and then with femoral components of varying stem length implanted to examine the distribution of stresses within the femur under increasing loads as a function of stem length. Our studies indicated that a stem is not an absolute requirement in order to achieve a well functioning, stable implant. However in order to reduce the possibility of mechanical failure a reduced stem or stemless implant absolutely must have three important characteristics to its design. First, it must have sufficient medial/lateral dimension to provide stability against subsidence and varus stress; second it must have a flat posterior surface, parallel and in contact with the posterior endosteal surface of the proximal femur with which to maximize A/P stability against flexion/extension forces (As a consequence of this design feature, appropriate anteversion must be achieved in the neck region of the prosthesis and not by rotation of the implant within the proximal metaphyseal cavity of the femur); and third, the implant must also have a cross-sectional geometry that will stabilize against torsional loading about the long axis of the femur. Therefore, simply reducing the length of an existing implant to accommodate changes in surgical techniques may not be a reasonable or safe design change. Such shortened versions of existing stem designs must be rigorously tested before being released for general use. The required design parameters outlined above have been clinically validated in custom fabricated implants. They have been shown to reduce aseptic loosening and migration of a short stem femoral implant. This report will provide the clinical review of a multi-center experience with the first 150 off-the-shelf “Lateral Flare” short stem implants

Over the last two decades, design modifications in cementless total hip arthoplasty have led to longer lasting implants and an increased success rate. However, there remains limitations to the cementless femoral stem implant. Traditional cementless femoral components require large amounts of bone to be broached prior to stem insertion (. 1. ). This leads to a decrease in host bone stock, which can become problematic in a young patient who may eventually require a revision operation during his or her lifetime. Osteopenia, only second to distal stress shielding can lead to aseptic loosening of the implant and stem subsidence, which also accelerates the need for a revision operation (. 2. –. 4. ). Recent literature suggests that thigh pain due to distal canal fixation, micro-motion, uneven stress patterns or cortex impingement by the femoral stem is directly correlated to increased stem sizes and often very disabling to a patient (. 5. –. 8. ). In this study, we sought to determine whether reducing stem length in the femoral implant would produce more physiologic loading characteristics in the proximal femur and thus eliminate any remaining stress shielding that is present in the current design. We analyzed the surface strains in 13 femurs implanted with. no implants,. stemless,. ultra short and. short stem proximal fill implants in a test rig designed to assimilate muscle forces across the hip joints, including the ilio-tibial band and the hip abductors. Analysis of the resulting surface strains was performed using the photoelastic method. For each femur, intact and with the different stem length components in place, the fringe patterns were compared at the same applied loads. The highest fringe orders observed for all tests were located on the lateral proximal femur and medial proximal femur. The fringes decreased as they approached the neutral axis of bending (posterior and anterior). Distal fringe patterns were more prominent as the stem length increased. The results demonstrate that the stemless design most closely replicated normal strain patterns seen in a native femur during simulated gait. The presence of a stemless, ultra short and short stem reduced proximal strain and increased distal strain linearly, thereby increasing the potential for stress shielding. The stemless design most closely replicated normal strain patterns observed in a native femur and for this reason has the potential to address the shortcomings of the traditional cementless femoral implant