Short stems have been developed to conserve bone stock, especially in younger populations undergoing a total hip arthroplasty (THA), and showed similar functional outcomes compared to conventional stems. Recent literature suggested that stem length might be an independent risk factor for acute periprosthetic femoral fracture in direct anterior THA (1) or with different short stem designs (2). The purpose of the present study was to compare the incidence of acute periprosthetic femoral fractures, between stems of the same manufacture (Taperloc microplasty vs Taperloc complete), which have the same stem characteristics, except for the stem length which is 35 mm shorter in Taperloc microplasty during posterior and lateral THA. Our institution's arthroplasty database was searched for all primary total hip arthroplasties utilizing short femoral stems performed between August 2016 and August 2023. Pre-operative X-rays for each case were analysed to characterize the proximal femoral geometry, specifically the canal bone ratio (CBR) and canal flare index (CFI). Data analysis was performed to identify risk factors for periprosthetic fractures. For the time period assessed, 2107 femoral stems (Taperloc Microplasty:1727, Taperloc complete: 380) were implanted. Females constituted 53% of the cohort. The average patient age was 70±11 years. The periprosthetic fracture rate was 0.94%, with 20 periprosthetic fractures (Taperloc Microplasty:17, Taperloc complete: 3) excluding 2 greater trochanteric fractures (1 at each group), identified at follow-up of three months. There was no significant difference between the periprosthetic fracture rates between the two stems (0.98% vs 0.79%, p>0.72) The multivariate regression analysis demonstrated that the stem length, CBR, CFI, age, and gender were not risk factors for periprosthetic fracture. The present study demonstrated that both Taperloc Microplasty and Taperloc complete stems had similar rates of periprosthetic fractures, and the stem length was not a risk factor for a periprosthetic fracture during uncemented THA. 1. Tamaki T, Cementless Tapered-Wedge Stem Length Affects the Risk of Periprosthetic Femoral Fractures in Direct Anterior Total Hip Arthroplasty. J Arthroplasty. 2018 Mar;33(3):805-809. 2. Staunton P. Acute Periprosthetic Hip Fracture with Short Uncemented Femoral Stems. J Arthroplasty 2024 accepted

Introduction. Short stems have been developed for some years for preservation of femoral bone stock and achieve physiological proximal loading. Shortening stem length is a merit for bone stock preservation. However, it might lead to reduction of primary stability. We investigated relationship between stem length and primary stability by patient specific finite element analysis (FEA). Materials and Methods. Thirty-one hips in 31 patients were performed total hip arthroplasty with standard length tapered wedge-shaped (TW) cementless stem (CTi-II: Corin, Cirencester, UK). There were 6 males and 25 females. The average age at operation was 69 years old. The average body mass index was 23.9 kg/m2. Primary diagnoses were secondary osteoarthritis due to developmental dysplasia of the hip in 29 hips. Femoral canal shapes were normal in 21, stovepipe in 6 and champagne-flute in 4 hips. Bone qualities were type A in 6, B in 19 and C in 6 hips. The patients underwent computed tomography (CT) preoperatively and postoperatively. We constructed preoperative three dimensional (3D) femur surface models from preoperative CT data with individual bone mineral density (BMD) mapping. The postoperative 3D femur and rough stem surface models were obtained from postoperative CT data. The coordinates of the postoperative femur were transformed to fit the preoperative femur model. A precise stem model constructed using computer-assisted design data was matched to the transformed rough stem model using the iterative closest point algorithm. We obtained a patient-specific model with the proximal bone geometry, allocation of BMD and stem alignment. We estimated the average of axial and rotational micromotion (MM) at stem-bone interface and the ratio of area (MM â�¦ 40 micrometers) on the porous surface in order to analyze primary stability of TW stem with several lengths (standard (100 %), 75 %, 50 %, 40 % and 30 % length). Results. The average MM in standard length stem was 14.3 micrometers and the ratio of area with MM â�¦ 40 micrometers was 97.9 %. The average of axial and rotational MM in shorter length (75 %) stem were respectively 9.7, 8.3 micrometers. There were no differences in the average of axial and rotational MM between standard and shorter (75 %) length stems. MM at the porous surface was increased as the stem length grew shorter. The ratio of area with MM â�¦ 40 micrometers on the porous surface were reduced by 50 to 80 % in −40 % or less length stem, comparing with the standard length stem. Discussion and Conclusion. The present FEA on the stem length and MM demonstrated that primary stability in 40 % or less short length TW stem was extensively reduced, which might lead to failure of bone ingrowth on the porous surface and early loosening. Shortening of stem length less than 50 % is a risk for reduced primary stability in TW stem

The current decade has seen a marked rise in popularity of minimally invasive hip replacement, done through a variety of surgical approaches. A specific downside to the direct anterior approach includes the significant difficulty getting a “straight shot” down the femoral canal for either straight, nonflexible reaming or broaching as with standard approaches. Improper alignment in the femoral canal can lead to sub-optimal load transfer and thus compromised fixation. The femoral broach and stem insertion path for this approach is best described as a curved one, rather than the typical straight path. Some femoral components appear to be more suitable to this technique due to their geometries. The purpose of the study was to describe the effects that the single geometric parameter, stem length, has on its insertion path into the femoral canal. Due to the potential introduction of human error associated with repetitively performing a specific motion, both a physical study and a computer generated analysis were conducted. For the physical portion of the study, a femoral implant body of generic fit and fill geometry was designed and manufactured. The length of the stem was varied from 40 mm to 100 mm in 10 mm increments. A medium sized synthetic femur (Sawbones, Pacific Labs, Seattle, WA) was machined to match the volume of the full length stem. The insertion path constraints were defined such that the stem had to maintain the greatest allowable insertion angle while still making contact on both the medial and lateral side of the canal during translation in the X direction. To reduce the variability in applying the constraints, a single author conducted the insertion procedure for each length stem while the path was videotaped from a fixed position directly in front of the setup. The most proximal lateral point of the stem was tracked through the insertion path and the X, Y coordinates were recorded at a frequency of 2 FPS. The area under this curve, referred to as the minimum insertion area (MIA), was calculated. For the computer generated portion of the study, a CAD model of the standard length Omnifit. ®. (Stryker Orthopaedics) was utilized. The stem was modified to create 5 additional models where the length was progressively shortened to 65%, 55%, 45%, 35%, and 25% of original length or 91mm, 77mm, 63mm, 49mm, and 35mm respectively. The femur was created from a solidified mesh of a computed tomography (CT) scan with the canal virtually broached for a full length stem. The models were each virtually assembled within the femoral canal with the similar constraints as the physical study. Again, the most proximal lateral point of the stem was tracked through the insertion path with the coordinates recorded and the MIA was calculated. There was a non-linear relationship between stem length and the MIA with the rate of change decreasing as the stem length decreased. That is, the greatest decrease in MIA was between the standard length and next longest length in the computer simulation. It was noted that marked change in MIA began to subside between the 77mm and 63mm stems and continued this trend of having less influence onward through to the shorter lengths. Although the results of the physical study showed a higher variability than the computer generated portion, it does confirm the results of the computer generated study. Minimizing the trauma associated with THR has led most of the above authors to the direct anterior approach. However, the femoral broach and stem insertion path is best described as a curved one, rather than the typical straight path used in other approaches. This curved insertion path also has benefits for other approaches since the broaches and stem can be kept away from the abductors, minimizing the potential injury to them. Shorter stem length makes this curved insertion path easier to perform. This is the first study to describe the effect that stem length has on its insertion path into the femoral canal. As expected, the physical portion of the study showed more variability than the computer generated portion. However, the physical and computer studies correlated well, with shorter stem lengths clearly allowing a more curved insertion path. The improvement tapered off in stem lengths below 63mm. This length correlates well with the other attempts at a shorter stem. This study provides quantitative data to help with shorter stem design and possible computer navigated insertion paths

Stress shielding (i.e. reduction in bone strains) in the distal ulna is commonly noted following ulnar head replacement arthroplasty. Optimal design parameters for distal ulnar implants, including the length of the stem, are currently unknown. The purpose of this study was to investigate the effect of stem length on bone strains along the length of the ulna. Strain gauges were applied to each of eight cadaveric ulnae to measure bending loads at six locations along each ulna’s length (approximately 1.5, 2.5, 4.0, 6.0, 8.0, and 13.0cm from the ulnar head). The proximal portion of each bone was secured in a custom-designed jig. A materials testing machine applied loads (5–30N) to the ulnar head while native strains were recorded. The ulnar head was removed and the loading procedure repeated for cemented stainless steel stems 3 and 7cm in length, according to a previously reported technique (Austman et al, CORS 2006). Other stem lengths between 3 and 7cm were tested in 0.5cm intervals with a 20N load applied only. Data were analyzed using a two-way repeated measures ANOVA (á=0.05). In general, distal bone strains increased as stem length decreased (e.g. average microstrains at the second distal-most gauges: 138±13 (7cm), 147±15 (6cm), 159±21 (5cm), 186±40 (4cm), 235±43 (3cm)). The native strains were different from all stem lengths for the four distal-most gauges (p< 0.05). No differences were found between any stem length and the native bone at the two proximal-most gauges. The 3cm stem replicated the native strains more closely than the 7cm, over all applied loads (e.g. average microstrains at the third gauge level for a 25N load: 357±59 (native), 396±74 (3cm), 257±34 (7cm)). No stem length tested matched the native strains at all gauge locations. The 3cm stem results were closer to the native strains than the 7cm stem for all loads at gauges overtop of the stem. Overall, the 3cm stem produced the highest strains, and thus would likely result in less distal ulnar bone resorption after implantation. These results suggest that shorter (approximately 3cm) stems should be considered for distal ulnar implants to potentially reduce stress shielding, although this must be balanced by adequate stem length for fixation

Introduction. Excellent long-term survival rates associated with the absence of stem subsidence have been achieved with total hip arthroplasty (THA) using femoral components cemented line-to-line (“French Paradox”). Recently, short stems have been introduced in order to preserve diaphyseal bone and to accommodate to minimal invasive THA and a variety of clinical situations. The aim of the current study was to quantify the rotational and tilting stability of a Kerboull stem of varying length after line-to-line cementation using a validated in-vitro model. Materials & methods. The femoral component made of M30NW stainless steel was derived from the original Kerboull stem. It had a double taper, a highly polished surface, and a quadrangular cross-section. Four stem lengths were designed from the original length with a distal reduction of 6, 12, 17 and 22%, whereas the proximal body geometry of the implant remained unaffected. For each stem length, five specimens were implanted into a non-canal synthetic femoral model. The femoral preparation was performed in order to obtain rotational and tilting stability of the stem prior to the line-to-line cementation. Spatial micro-motions of the specimens were investigated using a validated rotational measuring set-up. In addition, in a second separate step, the specimens were exposed to a ventro-dorsal moment to mimic varus-valgus moment. Statistical analysis was performed using ANOVA with Fisher PLSD. Results. The maximum torque transfer from the stem within the cement mantle to the composite femur occurred at the level of the lesser trochanter, whereas the lowest torque transfer was observed at the tip of the stem. The relative movement at the tip was significantly greater for the original length when compared to 6 and 12% length reduction (p = 0.036 and 0.033, respectively). The 12% reduction resulted in a significant lower mean overall movement when compared to the original length (p = 0.044). The tilting behavior according to the stem lengths indicated that proximal bending value was significantly increased for 17% reduction when compared to 6% and 12% reduction (p = 0.035 and 0.032, respectively). Bending of the tip of the stem was in the same direction as the shoulder, indicating a backlash from the tip. At the tip, relative bending was increased when compared to the previous length up to 12% reduction and then decreased. However, the difference was not significant (p <0.05). Discussion & conclusion. The stem lengths evaluated in the current study showed similar results to previously reported cemented stems of different designs, indicating a close fixation to composite bone with small relative movement. Both 6 and 12% shortened versions showed significant reduced relative movement at the tip when compared to the original length, suggesting a limited role for the tip in terms of rotational stability. Regarding the medio-lateral torque, the stems always reacted with a backlash and did not tilt like a rigid body. Although not significant, the distal bending tended to increase with reduced length. These findings led us to develop a Kerboull stem with 12% distal reduction that is currently under clinical trial

Objectives. Orthopaedic surgeons use stems in revision knee surgery to obtain stability when metaphyseal bone is missing. No consensus exists regarding stem size or method of fixation. This in vitro study investigated the influence of stem length and method of fixation on the pattern and level of relative motion at the bone–implant interface at a range of functional flexion angles. Methods. A custom test rig using differential variable reluctance transducers (DVRTs) was developed to record all translational and rotational motions at the bone–implant interface. Composite femurs were used. These were secured to permit variation in flexion angle from 0° to 90°. Cyclic loads were applied through a tibial component based on three peaks corresponding to 0°, 10° and 20° flexion from a normal walking cycle. Three different femoral components were investigated in this study for cementless and cemented interface conditions. Results. Relative motions were found to increase with flexion angle. Stemmed implants reduced relative motions in comparison to stemless implants for uncemented constructs. Relative motions for cemented implants were reduced to one-third of their equivalent uncemented constructs. Conclusions. Stems are not necessary for cemented implants when the metaphyseal bone is intact. Short cemented femoral stems confer as much stability as long uncemented stems

Purpose. Investigating the effects of femoral stem length on hip and knee muscle strength. Methods. The study included 20 patients having undergone total knee prostheses (TKP) due to coxarthrosis and 10 healthy subjects. Of the 20 patients, 10 underwent conventional TKP and 10 had Thrust Plate Prothesis (TPP). For the assessment of the patients’ muscle strength of operated and non-operated hips (Gl. medius and Gl. Maximus) and knees (Quadriceps Femoris-QF), the Hand-Held Dynamometer (HHD) was used. Results. A significant difference was observed in the muscle strength of Gl. medius in TPP patients and of Gl. maksimus in conventional TKP patients (p <0.05). Compared to the healthy group, only hip muscle strength decreased in TPP patients, but both hip and knee muscle strengths decreased in conventional TKP patients (p <0.05). Conclusion. A decrease in hip and knee muscle strengths was determined in the TPP and conventional THA patients, compared to healthy subjects. Compared to the bone protective prosthetic systems (eg TPP), a significant difference is observed in the QF muscle strength in intramedullary prosthesis applications. This data may be used in planning the treatment of patients with hip arthroplasty

Aims. There are concerns regarding initial stability and early periprosthetic fractures in cementless hip arthroplasty using short stems. This study aimed to investigate stress on the cortical bone around the stem and micromotions between the stem and cortical bone according to femoral stem length and positioning. Methods. In total, 12 femoral finite element models (FEMs) were constructed and tested in walking and stair-climbing. Femoral stems of three different lengths and two different positions were simulated, assuming press-fit fixation within each FEM. Stress on the cortical bone and micromotions between the stem and bone were measured in each condition. Results. Stress concentration was observed on the medial and lateral interfaces between the cortical bone and stem. With neutral stem insertion, mean stress over a region of interest was greater at the medial than lateral interface regardless of stem length, which increased as the stem shortened. Mean stress increased in the varus-inserted stems compared to the stems inserted neutrally, especially at the lateral interface in contact with the stem tip. The maximum stress was observed at the lateral interface in a varus-inserted short stem. All mean stresses were greater in stair-climbing condition than walking. Each micromotion was also greater in shorter stems and varus-inserted stems, and in stair-climbing condition. Conclusion. The stem should be inserted neutrally and stair-climbing movement should be avoided in the early postoperative period, in order to preserve early stability and reduce the possibility of thigh pain, especially when using a shorter stem. Cite this article: Bone Joint Res 2021;10(4):250–258

Introduction: Tibial component loosening is a common mode of failure in modern total knee arthroplasty and is thus a common cause for revision knee surgery. Direct bone ingrowth of press fit knee prosthesis has been deemed an important prerequisite for long-lasting implant fixation and thus clinical success in both primary and revision TKA whether for cemented or uncemented stems. To achieve good long term biological stabilization, initial secure mechanical stability, (i.e. minimising tibial tray and stem motion with respect to the tibia,) is vital. A lack of initial stability can lead to resorption of bone at the implant-tissue interface and can consequently result in loosening and failure of the prosthesis. Obtaining adequate tibial fixation is difficult in revision patients as often there is insufficient bone stock in the proximal tibia. A longer stem is often recommended with revision surgery as a central stem should guide the migration of the tibial component so that it occurs predominantly along the vertical axis, thus minimising the risk of recurrent malalignment and loosening due to tilting of the tibial tray. It is also thought that the presence of a third rigid peg helps to reduce inducible displacements by anchoring the new implant in robust cancellous bone. However there is no consensus on the length of central stem should be to achieve the best load transfer and fixation and although the use of long stems on the tibial component is advocated, in revision TKA involving bone grafting and augmentation. The effect of the tibial stem length in other cases has received contradictory evaluations. This research deals with an experimentally evaluate the effect that central stem lengths on the initial micromotion of the tibial tray in two revision tibial defects. This is being investigated by measurement of the bone-implant interface motion of the tibial stem. Method: Composite bones were resected with an extramedullary jig. Three common revision defects were compared 1) no defect requiring no repair(primary); 2) T1 defect requiring bone impaction grafting; 3) T2A requiring augmentation. Three stem configurations were analysed in conjunction with these defects 1) no stem; 2) short 40mm stem; 3) long 80mm stem. Four LVDTs were positioned anteriorly, posteriorly, medially and laterally around the tray and were used to measure the movement of the tibial tray with respect to the tibia. The bones were potted and subjected to axial loading simulating 1– 6 times body weight for 3500 cycles at 1 Hz. Results: The longer stemmed press fit implants were associated with slightly higher levels of micromotion compared to the “no stem press fit” trays in the primary and T2A defects. This could be due to the fact that cutting errors are accentuated by a longer stem and can cause increased levels of posterior lift off. For bone impaction grafting it seems that a stem sufficiently long to by-pass the defect should be used. The proximal surface cemented trays presented more stable fixation with the inducible displacement between the no stem and stemmed groups being negligible. Subsidence of the tibial tray was reduced marginally by using a longer stem

Introduction. The Exeter cemented polished tapered stem design was introduced into clinical practice in the early 1970's. [i] Design and cement visco-elastic properties define clinical results [ii]; a recent study by Carrington et al. reported the Exeter stem has 100% survivorship at 7 years. [iii] Exeter stems with offsets 37.5–56 mm have length 150 mm (shoulder to tip). Shorter stems, lengths 95–125 mm, exist in offsets 30–35.5 mm. The Australian National Joint Replacement Registry recently published that at 7 years the shorter stems are performing as well as longer stems on the registry [iv]. Clinical observation indicates in some cases of shorter, narrower femora that fully seating a 150 mm stem's rasp in the canal can be difficult, which may affect procedural efficiency. This study investigates the comparative risk of rasp distal contact for the Exeter 150 mm stem or a 125 mm stem. Materials and Methods. Rasps for 37.5, 44, 50 mm offset, No.1, 150 mm length stems (Exeter, Stryker Orthopaedics, Mahwah NJ) were compared with shortened length models using SOMA™ (Stryker Orthopaedics Modeling and Analytics technology). 637 patients' CT scanned femora were filtered for appropriate offset and size by measuring femoral-head to femoral-axis distance and midsection cancellous bone width (AP view). These femora were analyzed for distal contact (rasp to cortices) for 150 mm and 125 mm models (Figure 1). The widths of the rasp's distal tip and the cancellous bone boundary were compared to assess contact for each femur in the AP and ML views; the rasp was aligned along an ideal axis and flexed in order to pass through the femoral neck (ML view only). Results. The sample size of appropriate patients totaled 238 femora. In the AP view, the rasp exhibited contact in 43 cases for a 150 mm stem but in 0 cases for a 125 mm stem; 95% of bones with contact were Champagne Fluted. In the ML view, rasp distal contact occurred in 52 femora for a 150 mm stem and in 1 femur for a 125 mm stem (Table 1). The difference was significant in both views with p < 0.001. Discussion. This study shows that a shortened stem design's rasp avoids distal contact. Shorter stem rasps resolved all cases where there was a risk of contact with a 150 mm rasp and reduced the likelihood of contact (one case compared to 52), AP and ML views respectively. These results indicate that shorter stems may address patients with champagne-fluted and/or excessively bowed femora, commonly found in the Asian population[v]. Contact avoidance may improve rasp seating height (AP view) and alignment with the femoral axis (ML view), thereby increasing procedural efficiency and producing an optimal cement mantle distally.[vi] The data shows that a total 29% of appropriate model patients would benefit from a shorter stem. Shorter cemented stems may effectively address the global population's needs in THR

Introduction. Femoral component design is a key part of hip arthroplasty performance. We have previously reported that a hip resurfacing offered functional improved performance over a long stem. However resurfacing is not popular for many reasons, so there is a growing trend towards shorter femoral stems, which have the added benefit of ease of introduction through less invasive incisions. Concern is also developing about the impact of longer stems on lifetime risk of periprosthetic fracture, which should be reduced by the use of a shorter stem. For these reasons, we wanted to know whether a shorter stem offered any functional improvement over a conventional long stem. We surmised that longer stems in hip implants might stiffen the femoral shaft, altering the mechanical properties. Materials and Methods. From our database of over 800 patients who have been tested in the lab, we identified 95 patients with a hip replacement performed on only one side, with no other lower limb co-morbidities, and a control group:. 19 with long stem implant, age 66 ± 14 (LONG). 40 with short stem implant, age 69 ± 9 (SHORT). 26 with resurfacing, age 60 ± 8 (RESURF). 43 healthy control with no history of arthroplasty, age 59 ± 10 (CONTROL). All groups were matched for BMI and gender. Participants were asked to walk on an instrumented treadmill. Initially a 5 minute warm up at 4 km/h, then tests at increasing speed in 0.5 km/h increments. Maximum walking speed was determined by the patients themselves, or when subjects moved from walking to running. Ground reaction forces (GRF) were measured in 20 second intervals at each speed. Features were calculated based on the mean GRF for each trial, and on symmetry measures such as first peak force (heel strike), second peak force (toe-off), the rate at which the foot was loaded and unloaded, and step length. Results. When measured by top walking speed, stemmed implants of either type appear slower than those which do not include the femoral shaft (resurfacing). The latter group walking speed was equal to the control group (Figure 1). When looking at the whole gait cycle at any one speed, no major differences appear in the first or second peak forces (Figure 2 – 5km/h, implanted side compared). When checked for asymmetry, resurfacing patients did not demonstrate any asymmetry between legs, while either stemmed groups demonstrated slight differences between legs in terms of force related features (Figure 3). Discussion. We sought to show if stem length has an impact on top walking speed and asymmetry of gait. This small study contributes to that debate. We could not demonstrate any functional superiority of the short over the long stem, but the short femoral stem seems to transmit load just as well as the longer stem, allowing good load transfer at toe-off, and comparable walking speed. The results stress the advantages of non stemmed implants as published before. Our study adds to the discussion as to whether long stems are still needed in primary arthroplasty

Purpose: While computer-assisted techniques can improve the alignment of the implant articulation with the native structure, stem abutment in the intramedullary canal may impede achievement of this alignment. In the current study, the effect of a fixed valgus (6 degree) stemmed humeral component on the alignment of navigated total elbow arthroplasty was investigated. Our hypothesis was that implantation of a humeral component with a reduced stem length would be more accurate than implantation of the humeral component with a standard length stem. Method: Thirteen cadaveric distal humeri were imaged using a CT scanner, and a 3D surface model was reconstructed from each scan. Implantation was performed using two implant configurations. The first set was unmodified (Regular) while the second set was modified by reducing the length of the humeral stem to 25% of the original stem (Reduced). A surface model of the humeral component was aligned with the flexion-extension (FE) axis of the CT-based surface model, which was registered to the landmarks of the physical humerus using the iterative closest point algorithm. Navigated implant positioning was based on aligning a 3D computer model calibrated to the implant with a 3D model registered to the distal humerus. Results: Implant alignment error was significantly lower for the Reduced implant, averaging 1.3±0.5 mm in translation and 1.2±0.4° in rotation, compared with 1.9±1.1 mm and 3.6±2.1° for the Regular implant. Abutment of the implant stem with the medullary canal of the humerus prevented optimal alignment of the Regular humeral component as only four of the 13 implantations were aligned to within 2.0° using navigation. Conclusion: These results demonstrate that a humeral component with a fixed valgus angulation cannot be accurately positioned in a consistent fashion within the medullary canal of the distal humerus without sacrificing alignment of the FE axis due to stem abutment. Improved accuracy of implant placement can be achieved by introducing a family of humeral components, with three valgus angulations of 0°, 4° and 8°. Based on humeral morphology for these specimens, 12 of the 13 implants may be positioned to within 2° of the native FE axis using one of these 3 valgus angulations

In this RCT the primary aim was to assess whether a short (125mm) Exeter V40 stem offered an equivalent hip specific function compared to the standard (150mm) stem when used for cemented total hip arthroplasty (THA). Secondary aims were to evaluate health-related quality of life (HRQoL), patient satisfaction, stem height and alignment, radiographic loosening, and complications between the two stems.

A prospective multicentre double-blind randomised control trial was conducted. During a 15-month period, 220 patients undergoing THA were randomised to either a standard (n=110) or short (n=110) stem Exeter. There were no significant (p≥0.065) differences in preoperative variables between the groups. Functional outcomes and radiographic assessment were undertaken at 1- and 2-years.

There were no differences (p=0.428) in hip specific function according to the Oxford hip score at 1-year (primary endpoint) or at 2-years (p=0.767) between the groups. The short stem group had greater varus angulation (0.9 degrees, p=0.003) when compared to the standard group and were more likely (odds ratio 2.42, p=0.002) to have varus stem alignment beyond one standard deviation from the mean. There were no significant (p≥0.083) differences in the Forgotten joint scores, EuroQol-5-Dimension, EuroQol-VAS, Short form 12, patient satisfaction, complications, stem height or radiolucent zones at 1 or 2-years between the groups.

The Exeter short stem offers equivalent hip specific function, HRQoL, patient satisfaction, and limb length when compared to the standard stem at 2-years post-operation. However, the short stem was associated with a greater rate of varus malalignment which may influence future implant survival.

Although data on uncemented short stems are available, studies on cemented short-stemmed THAs are limited. These cemented short stems may have inferior long-term outcomes and higher femoral component fracture rates. Hence, we examined the long-term follow-up of cemented short Exeter stems used in primary THA. Within the Exeter stem range, 7 stems have a stem length of 125 mm or less. These stems are often used in small patients, in young patients with a narrow femoral canal or patients with anatomical abnormalities. Based on our local database, we included 394 consecutive cemented stems used in primary THA (n=333 patients) with a stem length ≤125 mm implanted in our tertiary referral center between 1993 and December 2021. We used the Dutch Arthroplasty Registry (LROI) to complete and cross-check the data. Kaplan-Meier survival analyses were performed to determine 20-year survival rates with stem revision for any reason, for septic loosening, for aseptic loosening and for femoral component fracture as endpoints. The proportion of male patients was 21% (n=83). Median age at surgery was 42 years (interquartile range: 30–55). The main indication for primary THA was childhood hip diseases (51%). The 20-year stem survival rate of the short stem was 85.4% (95% CI: 73.9–92.0) for revision for any reason and 96.2% (95%CI: 90.5–98.5) for revision for septic loosening. No stems were revised for aseptic femoral loosening. However, there were 4 stem fractures at 6.6, 11.6, 16.5 and 18.2 years of follow-up. The stem survival with femoral component fracture as endpoint was 92.7% (CI: 78.5–97.6) at 20 years. Cemented short Exeter stems in primary THA show acceptable survival rates at long-term follow-up. Although femoral component fracture is a rare complication of a cemented short Exeter stem, orthopaedic surgeons should be aware of its incidence and possible risk factors

Aims. Although good clinical outcomes have been reported for monolithic tapered, fluted, titanium stems (TFTS), early results showed high rates of subsidence. Advances in stem design may mitigate these concerns. This study reports on the use of a current monolithic TFTS for a variety of indications. Methods. A multi-institutional retrospective study of all consecutive total hip arthroplasty (THA) and revision total hip arthroplasty (rTHA) patients who received the monolithic TFTS was conducted. Surgery was performed by eight fellowship-trained arthroplasty surgeons at four institutions. A total of 157 hips in 153 patients at a mean follow-up of 11.6 months (SD7.8) were included. Mean patient age at the time of surgery was 67.4 years (SD 13.3) and mean body mass index (BMI) was 28.9 kg/m. 2. (SD 6.5). Outcomes included intraoperative complications, one-year all-cause re-revisions, and subsidence at postoperative time intervals (two weeks, six weeks, six months, nine months, and one year). Results. There were eight intraoperative complications (4.9%), six of which were intraoperative fractures; none occurred during stem insertion. Six hips (3.7%) underwent re-revision within one year; only one procedure involved removal of the prosthesis due to infection. Mean total subsidence at latest follow-up was 1.64 mm (SD 2.47). Overall, 17 of 144 stems (11.8%) on which measurements could be performed had >5 mm of subsidence, and 3/144 (2.1%) had >10 mm of subsidence within one year. A univariate regression analysis found that additional subsidence after three months was minimal. A multivariate regression analysis found that subsidence was not significantly associated with periprosthetic fracture as an indication for surgery, the presence of an extended trochanteric osteotomy (ETO), Paprosky classification of femoral bone loss, stem length, or type of procedure performed (i.e. full revision vs conversion/primary). Conclusion. Advances in implant design, improved trials, a range of stem lengths and diameters, and high offset options mitigate concerns of early subsidence and dislocation with monolithic TFTS, making them a valuable option for femoral revision. Cite this article: Bone Joint J 2020;102-B(2):191–197

Aims. The aim of this study was to evaluate the kinematics of the elbow following increasing length of the radius with implantation of radial head arthroplasties (RHAs) using dynamic radiostereometry (dRSA). Methods. Eight human donor arms were examined by dRSA during motor-controlled flexion and extension of the elbow with the forearm in an unloaded neutral position, and in pronation and supination with and without a 10 N valgus or varus load, respectively. The elbows were examined before and after RHA with stem lengths of anatomical size, + 2 mm, and + 4 mm. The ligaments were maintained intact by using a step-cut lateral humeral epicondylar osteotomy, allowing the RHAs to be repeatedly exchanged. Bone models were obtained from CT scans, and specialized software was used to match these models with the dRSA recordings. The flexion kinematics of the elbow were described using anatomical coordinate systems to define translations and rotations with six degrees of freedom. Results. The greatest kinematic changes in the elbows were seen with the longest, + 4 mm, implant, which imposed a mean joint distraction of 2.8 mm in the radiohumeral joint and of 1.1 mm in the ulnohumeral joint, an increased mean varus angle of up to 2.4° for both the radius and the ulna, a mean shift of the radius of 2.0 mm in the ulnar direction, and a mean shift of the ulna of 1.0 mm posteriorly. Conclusion. The kinematics of the elbow deviated increasingly from those of the native joint with a 2 mm to a 4 mm lengthening of the radius. This confirms the importance of restoring the natural length of the radius when undertaking RHA. Cite this article: Bone Joint J 2024;106-B(10):1165–1175

There is a paucity of long-term data on modular fluted tapered (MFT) stems for two-stage reimplantation following periprosthetic joint infection (PJI). The purpose of this study was to evaluate implant survivorship, radiographic results, and clinical outcomes in a large cohort of reimplantation THAs using MFT stems. We identified 236 reimplantation THAs from a single tertiary care academic institution from 2000 to 2020. Two designs of MFT stems were used as part of an established two-stage exchange protocol for the treatment of PJI. Mean age at reimplantation was 65 years, mean BMI was 32 kg/m. 2. , and 46% were female. Median stem diameter was 19 mm, and median stem length was 195 mm. Mean follow-up was 7 years. A competing risk model accounting for death was utilized. The 15-year cumulative incidence of any revision was 24%. There were 48 revisions, with the most common reasons being dislocation (n=25) and PJI (n=16). The 15-year cumulative incidence of any reoperation was 28%. Only 13 revisions involved the fluted tapered portion of the component (FTC), for a 15-year cumulative incidence of any FTC revision of 8%. Only 2 FTCs were revised for aseptic loosening, resulting in a 15-year cumulative incidence of FTC revision for aseptic loosening of 1%. Stem subsidence >5 mm occurred in 2% of unrevised cases, and all stems were radiographically stable at most recent follow-up. Mean HHS was 77 at most recent follow-up. This series demonstrated that MFT stems were durable and reliable even in the setting of two-stage reimplantation for infection. While the incidence of aseptic loosening was very low, the incidence of any revision was 24% at 15 years, primarily caused by dislocation and recurrent PJI. Level of Evidence: IV

Revision total hip arthroplasty (rTHA) in the presence of femoral defects can be technically challenging. Reconstruction with long stems is widely accepted as the standard. However long stems can be difficult to insert and can compromise distal bone stock for future revisions. The aims of this study were to identify whether there was a difference in survival and outcomes following rTHA using a long versus standard or short femoral stem. A comprehensive systematic review was performed according to PRISMA guidelines using the MEDLINE, EMBASE, Chochrane Library and Web of Science databases. Inclusion criteria were (i) adult patients >18 years; (ii) randomised controlled trials, joint registry, or cohort studies; (iii) single or staged rTHA for Paprosky 1–3B femoral defects. Exclusion criteria were (i) mixed reporting without subgroup analysis for revision stem length; (ii) ex-vivo studies. Screening for eligibility and assessment of studies was performed by the authors. Out of 341 records, 9 studies met criteria for analysis (including 1 study utilising joint registry data and 1 randomised controlled trial). Across studies there were 3102 rTHAs performed in 2982 patients with a mean age of 67.4 years and a male: female ratio of 0.93. Revision prostheses were long-stemmed in 1727 cases and short or standard in 1375 cases with a mean follow up of 5 years (range, 0-15 years). On subgroup analysis the use of a long cemented stem compared to a long cementless prosthesis was associated with fewer complications and periprosthetic fracture in older patients. Survivorship was 95% with short stems compared to 84% with long stems at 5 years. Moderate quality evidence suggests that in rTHA with Paprosky type 1-3B femoral defects, the use of a short or standard stem can achieve comparable outcomes to long stems with fewer significant complications and revisions. Using a shorter stem may yield a more straightforward surgical technique and can preserve distal bone stock for future revision

Aims. Stemmed tibial components are frequently used in revision total knee arthroplasty (TKA). The purpose of this study was to evaluate patient satisfaction, overall pain, and diaphyseal tibial pain in patients who underwent revision TKA with cemented or uncemented stemmed tibial components. Methods. This is a retrospective cohort study involving 110 patients with revision TKA with cemented versus uncemented stemmed tibial components. Patients who underwent revision TKA with stemmed tibial components over a 15-year period at a single institution with at least two-year follow-up were assessed. Pain was evaluated through postal surveys. There were 63 patients with cemented tibial stems and 47 with uncemented stems. Radiographs and Knee Society Scores were used to evaluate for objective findings associated with pain or patient dissatisfaction. Postal surveys were analyzed using Fisher’s exact test and the independent-samples t-test. Logistic regression was used to adjust for age, sex, and preoperative bone loss. Results. No statistically significant differences in stem length, operative side, or indications for revision were found between the two cohorts. Tibial pain at the end of the stem was present in 25.3% (16/63) of cemented stems and 25.5% (12/47) of uncemented stems (p = 1.000); 74.6% (47/63) of cemented patients and 78.7% (37/47) of uncemented patients were satisfied following revision TKA (p = 0.657). Conclusion. There were no differences in patient satisfaction, overall pain, and diaphyseal tibial pain in cemented and uncemented stemmed tibial components in revision TKA. Patient factors, rather than implant selection and surgical technique, likely play a large role in the presence of postoperative pain. Stemmed tibial components have been shown to be a possible source of pain in revision TKA. There is no difference in patient satisfaction or postoperative pain with cemented or uncemented stemmed tibial components in revision TKA. Cite this article: Bone Joint J 2021;103-B(6 Supple A):165–170

Aims. The Exeter V40 cemented polished tapered stem system has demonstrated excellent long-term outcomes. This paper presents a systematic review of the existing literature and reports on a large case series comparing implant fractures between the Exeter V40 series; 125 mm and conventional length stem systems. Methods. A systematic literature search was performed adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. In parallel, we performed a retrospective single centre study of Exeter V40 femoral stem prosthetic fractures between April 2003 and June 2020. Results. There are 25 reported cases of such prosthetic fractures confined to small case series and case reports within the literature. We report an additional 19 cases to the literature (mean age 66.3 years (SD 11.7); 12 (63%) females; BMI 32.9 kg/m. 2. (SD 5.9)). The mean time from index procedure to fracture was 7.8 years (SD 3.6; 2.5 to 16.3). Exeter V40 stem fracture incidence was 0.15% and 1.21% for primary and revision arthroplasty, respectively. Incidence was significantly higher in revision arthroplasty (p < 0.001) and 125 mm length stems compared to ≥ 150 mm length stems (1.25% vs 0.13%, respectively; p < 0.001). When comparing different stem length cohorts, 125 mm short-stems were associated with stem-body fractures (92% vs 29%; p = 0.0095), earlier time to fracture (6.2 years vs 11.0 years; p = 0.0018), younger patient age at time of fracture (62.7 years vs 72.6 years; p = 0.037), and female sex (75% vs 43%; p = 0.326). Conclusion. This complication remains rare, although we report a significantly higher incidence at up to 17 years follow-up than in the literature. Short 125 mm length Exeter V40 stems undoubtedly have a role in restoring anatomy and biomechanics in smaller femoral geometries, although the surgeon has to appreciate the higher risk of stem fracture and the associated predisposing factors which may necessitate particular attention to surgical technique and planning. Cite this article: Bone Jt Open 2021;2(6):443–456