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

Cement-in-cement revision of the femoral component represents a widely practiced technique for a variety of indications. In this study we compare the clinical and radiological outcomes of two polished tapered stems. From our prospectively collated database we identified all patients undergoing cement-in-cement revision from January 2005 – 2013 who had a minimum of two years follow-up. All cases were performed by the senior author using either an Exeter short revision stem or the C-stem AMT high offset No 1. Patients were followed-up annually with clinical and radiological assessment. Ninety-seven patients matched the inclusion criteria. There were 50 Exeter and 47 C-stem AMT components. There were no significant differences between the patient demographics in either group. Mean follow-up was 9.7 years. A significant improvement in OHS, WOMAC and SF-12 scores was observed in both cohorts. Leg lengths were significantly shorter in the Exeter group, with a mean of -4mm in this cohort compared to 0mm in the C-stem AMT group. One patient in the Exeter group had early evidence of radiological loosening. In total, 16 patients (15%) underwent further revision of the femoral component (seven in the C-stem AMT group and nine in the Exeter group). No femoral components were revised for aseptic loosening. There were two cases of femoral component fracture in the Exeter group. Our series shows promising long-term outcomes for the cement-in-cement revision technique using either the Exeter or C-stem AMT components. These results demonstrate that cement-in-cement revision using a double or triple taper-slip design is a safe and reliable technique when used for the correct indications

Femoral component fracture is a rarely reported but devastating complication of total knee arthroplasty. It has occurred most frequently with Whiteside Ortholoc II replacements uncemented knee replacements. Presentation may be with acute pain, progressive pain or returning deformity. It occurs more commonly in the medial condyle of the femoral component. It is rarely seen in cemented replacements. All currently available literature describing fractures of condylar replacements, both cemented and uncemented. Predisposing factors include varus deformity either pre or post operatively. The mechanism of failure is thought to be failure of the infiltration of bone into the replacement. This is often due to polyethylene wear or metallosis causing abnormal tissue reaction with or without osteolysis. We present the case of a fractured Press Fit Condylar (PFC) cemented implant (DePuy, Johnson&Johnson, Raynham, Massachusettes, USA) affecting the medial condyle. To our knowledge this is only the third reported case of fracture in a PFC implant, and the first in a cemented PFC implant. Our patient was a 64 year old male who presented with unresolving knee pain post total knee arthroplasty, caused by fatigue fracture of the medial condyle of the femoral component. This was identified as loosening on plain radiographs and replaced with a revision prosthesis with a good post operative result. Given our aging population and with the increase of joint arthroplasty, this case sheds light on a potentially under recognised and increasingly important cause of knee pain following arthroplasty

Purpose of Study: Fixed bearing unicompartmental knee replacement (UKR) has become popular since several series have shown good 10 year survivorship and excellent function. However little is known about survival during the second decade. Method: From the Bristol database of over 4000 knee replacements 203 St. George Sled UKR’s which had already survived 10 years were identified. The mean age at surgery was 67 years (48–85), with 64% being female. This cohort has been further reviewed at an average of 14.8 years (10–30) from surgery to determine survivor-ship and function. Results: Survivorship during the second decade was 87.5%. 58 patients (69 knees) had deceased with implant in situ, only 2 after revision. A further 15 UKR’s have been revised at an average of 13 years post op; 7 for progression of disease, 4 for tibial loosening, 3 for polyethylene wear, 2 for femoral component fracture and 2 for infection. 99 knees were followed for 15 years and 21 knees for 20 years. The average Bristol knee score of the surviving knees fell from 86 to 79 during the second decade. A previous study showed an 89% 10 year survivor-ship and this is now extended to 82% at 15 years and 76.5% at 20 years. Conclusion: Satisfactory survival of fixed bearing UKR can be achieved in the second decade suggesting that the indications for mobile bearings require careful definition since there is a higher incidence of complications in many people’s hands

Purpose of Study: Fixed bearing unicompartmental knee replacement (UKR) has become popular since several series have now shown good 10 year survivorship and excellent function. However little is known about survival during the second decade. Method: From the Bristol database of over 4000 knee replacements 203 St. Georg Sled UKR’s which had already survived 10 years were identified. The mean age at surgery was 67 years (48–85), with 64% being female. This cohort has been further reviewed at an average of 14.8 years (10–30) from surgery to determine survivorship and function. Results: Survivorship during the second decade was 87.5%. 58 patients (69 knees) had died with implant in situ and only 2 after revision. A further 15 UKR’s have been revised at an average of 13 years post op; 7 for progression of disease in the opposite compartment, 4 for tibial loosening, 3 for polyethylene wear, 2 for femoral component fracture and 2 for infection. 99 knees were followed for 15 years, 21 knees for 20 years and four for 25 or more years. The average Bristol knee score of the surviving knees fell from 86 to 79 during the second decade, largely as a result of aging. A previous study of the St Georg. Fixed bearing UKR showed an 89% 10 year survivorship and this is now extended to 82% at 15 years and 76.5% at 20 years. Conclusion: Satisfactory survival of fixed bearing UKR can be achieved in the second decade suggesting that the indications for mobile bearings require careful definition since there is a higher incidence of complications in many people’s hands

39 consecutive patients (40 hips) undergoing femoral impaction grafting were retrospectively reviewed to assess our mid-term results and analyse them for any factors that could influence outcome. 36 revisions were for aseptic loosening, 3 for infection and 1 following a periprosthetic fracture. Those hips revised for infection were revised in 2 stages. In 37 cases, the Exeter X-Change bone impaction technique was used, implanting an Exeter stem with Simplex cement through a posterior approach. A Charnley stem was implanted in the 3 others. Each surviving patient was assessed using the Harris hip score, AP pelvis and lateral hip radiographs. Potential prognostic factors were analysed using the Spearman’s rank correlation test. The patients were reviewed after a mean follow-up of 5 years. 1 patient didn’t wish to attend review but was asymptomatic. Complications included 4 intraoperative femoral fractures during cement removal, 2 postoperative femoral fractures, 2 dislocations, 1 femoral component fracture and 1 deep infection. There were 3 re-revisions and 1 Girdlestones procedure. The median Harris hip score of those implants still in-situ was 78.5. Those patients who had previously undergone a revision had a significantly worse Harris hip score (p< 0.05). The patients age, reason for revision, preoperative bone loss, surgeon, simultaneous acetabular revision, simultaneous bone grafting to acetabulum, loose acetabular component on radiographs, femoral subsidence, presence of trabeculae in the graft, any radiolucency, a complete cement mantle and ectopic bone formation had no significant correlation to the Harris hip score. In this series, previous revision was found to be the only significant risk factor for a poor Harris hip score after femoral impaction grafting. Postoperative radiographic changes in this group correlated poorly with function and could not predict outcome. Further study is required to assess other factors such as bone graft and soft tissue quality that may also predict outcome

Introduction and Aims: Currently, multiple femoral component types and sizes exist for primary total hip arthroplasty. However, component sizes for small femoral geometry are generally not available. The purpose of this study is to present the short-term use of a femoral component with sizes that extend into small femoral morphometry applications. Method: Between November 2001 and December 2003, 20 primary THA cases and three revision THA cases were performed utilising a non-cemented, dual threaded, cone shaped (DTCS) modular femoral component manufactured in off-the-shelf sizes, which include those sizes for small femora. The components are made of CoCr and include a size ‘Z’ (19mm proximal, 9mm distal) and a size ‘Y’ (17mm proximal, 8mm distal). Both components have hydroxyapatite coating for stimulating increased bone on-growth and a modular neck allowing intra-operative adjustments of leg length, version, offset and neck length. Results: The average patient follow-up was 10 months (range 64 days to 27 months). There were 19 (83%) hips in which the ‘Z’ component was used, and four (17%) hips with the ‘Y’ component. Radiographic evaluation revealed well-fixed and positioned components with evidence of bone densing in areas in intimate contact with the DTCS component. Radiographic evidence of minor stress shielding was observed in the greater trochanter (Gruen Zone 1) and the proximal calcar/neck cut region (Gruen Zone 7). Two revision cases (8%) required the additional use of a 6cm modular extension component (MEC) to bridge a proximal femoral deficiency. Two cases (8%) required adjunctive strut allografting at the time of surgery to protect a thin or deficient femoral cortex. There were no reported postoperative complications related to the femoral component. There was no disassociation of the modular neck from the femoral stem and there was no incidence of femoral component fracture. Conclusion: While expanding component profile offerings into larger sizes is common, developing similar component designs for abnormally small femora is uncommon, beyond the scope of the materials used and only done as a ‘custom’ order. The DTCS modular femoral component used affords a versatile option when presented with cases involving small femoral morphometry. We conclude that the DTCS component in smaller sizes is promising and warranted for continued use

Introduction The clinical use of an all-polymer knee which articulated a polyacetal femoral component against an ultra high molecular weight polyethylene (UHMWPE) tibial component has been reported [. 1. ]. A ‘polyacetal group’ of 63 total knee replacements were followed for at least ten years and no instances of femoral component fracture or failure due to wear occurred [. 1. ]. Such results are remarkable for an all-polymer pros-thesis in such a heavily loaded joint as the knee. Recently a wear screening device has been described which reproduced in vitro the clinical wear rates reported for three biopolymers which have been employed as the acetabular cup material in hip prostheses [. 2. ]. Given this validated rig, the objective of the work reported here was to undertake wear tests of polyacetal against UHMWPE. Materials and Methods The polyacetal and UHMWPE couples were tested using a modified, four-station, pin-on-plate wear test rig [. 2. ]. The modification entailed the addition of rotational motion to the test pins, in addition to the standard reciprocating motion, to give multi-directional motion. In the wear tests, two stations had reciprocation-only and two applied multi-directional motion. Investigating the influence of both types of motion permitted a fuller tribological analysis to be undertaken. Control pins and control plates were included to account for any weight change due to lubricant uptake. A load of 40N was employed and reciprocating and rotating speeds of 1Hz were chosen. The lubricant consisted of 25% bovine calf serum and 75% distilled water, which was heated to 37°C during testing. A standardised cleaning and weighing protocol was followed, and the pins and plates were weighed on a balance sensitive to 0.1mg. Results and Discussion After an average of 1.4 million cycles of sliding, the mean wear factors were: UHMWPE pins rubbing against polyacetal plates, 1.5 x 10-6mm3/ Nm under reciprocation, and 4.1 x 10-6mm3/Nm under multi-directional motion. For polyacetal pins rubbing against UHMWPE plates they were 0.7 x 10-6mm3/ Nm under reciprocation, and 2.8 x 10-6mm3/Nm under multi-directional motion. As can be seen, the wear factors depended on both the orientation of the material, whether it was a pin or a plate, and the motion it was subjected to. The increase in weight of the polyacetal control components due to lubricant uptake was many times that of the UHMWPE components. For example the UHMWPE control plate showed an increase of 0.2mg compared with 33.4mg for the polyacetal control plate. Using the same wear screening rig, the wear factors for UHMWPE articulating against stainless steel were measured to be 0.1 x10-6mm3/Nm under reciprocating motion and 1.1 x10-6mm3/Nm under multi-directional motion [. 2. ]. Though greater than this latter value, the all-polymer wear factors were not excessively high and were less under reciprocation-only. How much multi-directional motion, or cross-shear, it is appropriate to apply to a wear simulation of an artificial knee joint is worth further investigation, as it may be much less than in the hip joint

Cementless knee arthroplasty has seen a recent resurgence in popularity due to conceptual advantages, including improved osseointegration providing biological fixation, increased surgical efficiency, and reduced systemic complications associated with cement impaction and wear from cement debris. Increasingly younger and higher demand patients are requiring knee arthroplasty, and as such, there is optimism cementless fixation may improve implant survivorship and functional outcomes.

Compared to cemented implants, the National Joint Registry (NJR) currently reports higher revision rates in cementless total knee arthroplasty (TKA), but lower in unicompartmental knee arthroplasty (UKA). However, recent studies are beginning to show excellent outcomes with cementless implants, particularly with UKA which has shown superior performance to cemented varieties. Cementless TKA has yet to show long-term benefit, and currently performs equivalently to cemented in short- to medium-term cohort studies. However, with novel concepts including 3D-printed coatings, robotic-assisted surgery, radiostereometric analysis, and kinematic or functional knee alignment principles, it is hoped they may help improve the outcomes of cementless TKA in the long-term. In addition, though cementless implant costs remain higher due to novel implant coatings, it is speculated cost-effectiveness can be achieved through greater surgical efficiency and potential reduction in revision costs. There is paucity of level one data on long-term outcomes between fixation methods and the cost-effectiveness of modern cementless knee arthroplasty.

This review explores recent literature on cementless knee arthroplasty, with regards to clinical outcomes, implant survivorship, complications, and cost-effectiveness; providing a concise update to assist clinicians on implant choice.

Cite this article: Bone Jt Open 2021;2(1):48–57.

Purpose: To compare the early results and complications associated with two different minimally invasive surgical techniques, the mini-posterior and G3 approaches. Method: The senior author prospectively allocated successive patients into either posterior or G3 groups for all primary total hip replacements from April 2005 to July 2006. Results: Of 173 hips, 116 hips were introduced via a mini-posterior approach, 57 via a G3. There were no significant differences in composition of the two groups in average age, gender, length of hospital stay, or early functional outcome. The posterior group patients were generally heavier, but OR time was significantly less than in the G3 group, as were blood transfusion rates. Technical issues were noted in 25% of cases, including calcar and periprosthetic fracture (9), malposition of the acetabular and femoral components (6), and leg length discrepancies (28). There was one death and one infection. There were 3 dislocations, from both groups, deemed to be more a function of improper component implantation, rather than of the surgical approach. Of 4 with neurologic symptoms, one patient from each group experienced anterior thigh numbness with activity; in the G3 group there was a lateral femoral cutaneous nerve deficit, and a severe sciatic nerve deficit. There were 7 (4%) patients who required additional surgery, 5 for periprosthetic fracture or implant malposition. Two re-operations were attributed to being likely specific to the surgical approach and its limited visualization, both G3s with femoral component malposition. Technically it was appreciated that there was a fine line between a too tight femoral component (heightened fracture risk) and one too loose (heightened subsidence risk). The strengths of this study are that it reflects the experience of one career arthroplasty surgeon performing a consecutive, nearly randomized to two MIS approaches, consecutive case series of primary total hip arthroplasties, using the same fiber-metal acetabulum and tapered fiber-metal HA coated femur prostheses in all cases. Conclusion: The G3 approach is technically difficult, with a long “learning curve”. This difficulty was acutely accentuated in larger patients. The mini-posterior incision was relatively easy, even in the larger patient, and became the preferred approach for the more challenging case