Abstract. Introduction. Cementless fixation of Oxford Unicompartmental Knee Replacements (UKRs) is an alternative to cemented fixation, however, it is unknown whether cementless fixation is as good long-term. This study aimed to compare primary and long-term fixation of cemented and cementless Oxford UKRs using radiostereometric analysis (RSA). Methodology. Twenty-nine patients were randomised to receive cemented or cementless Oxford UKRs and followed for ten years. Differences in primary fixation and long-term fixation of the tibial components (inferred from 0/3/6-month and 6-month/1-year/2-year/5-year/10-year migration, respectively) were analysed using RSA and radiolucencies were assessed on radiographs. Migration rates were determined by linear regression and clinical outcomes measured using the Oxford Knee Score (OKS). Results. Preliminary analysis of Maximum Total Point Motion (MTPM) indicated cementless tibial components undergo significantly more migration than cemented components during the first 6 months (1.6mm/year, SD=0.92 versus 1.3mm/year, SD=1.1, p<0.001). Cementless migration was predominantly subsidence inferiorly (Mean=0.51mm/year, SD=0.29, p<0.001) and posteriorly (0.13mm/year, SD=0.21, p=0.03). Contrastingly, from 6 months to 10 years cemented components migrated significantly (MTPM=0.039mm/year, SD=0.11, p=0.04) whereas cementless components did not (MTPM=0.002mm/year, SD=0.02, p=0.744). Radiolucent lines occurred more frequently below cemented (10/13) than cementless (4/16) tibial components, but radiolucencies did not correlate with differences in migration or OKS. There was no significant difference in OKS between cemented and cementless. Conclusion. These results suggest that cementless tibial components migrate more than cemented before achieving primary fixation. However, long-term fixation of cementless tibial components appears to be as good, if not better, than cemented with the benefit of fewer radiolucent lines

Introduction. Patients with FNF may be treated by either total hip arthroplasty (THA) or hemiarthroplasty (HA). Utilizing American Joint Replacement Registry (AJRR) data, we aimed to evaluate outcomes in FNF treatment. Methods. Medicare patients with FNF treated with HA or THA reported to the AJRR database from 2012–2019 and CMS claims data from 2012–2017 were analyzed in this retrospective cohort study. “Early” was defined as less than 90 days from index procedure. A logistic regression model, including index arthroplasty, age, sex, stem fixation method, hospital size. 1. , hospital teaching affiliation. 1. , and Charlson comorbidity index (CCI), was utilized to determine associations between index procedure and revision rates. Results. Of 75,333 FNF procedures analyzed, 82.2% had HA. 8.4% had cemented fixation. 36.9% had cementless fixation. Fixation was unknown for 41,225 (54.7%) patients. 90-day readmissions rates were 1.3% for both cohorts. Both the early revision rate (0.9% HA vs. 1.3% THA, p<0.0001) as well as the overall revision rate (1.5% HA vs. 2.3% THA, p<0.0001) were higher in the THA cohort. The three most common reasons for any revision were instability (26%), infection (21%), and periprosthetic fracture (15%). Higher rates of any revision were associated with cementless fixation (OR=1.37, 95% CI 1.20–1.57) and increased age (OR=0.96, 95% CI 0.96–0.97). THA and increased age were risk factors for early and any revision for instability. Cementless fixation, female sex, and decreased age were associated with lower revision rates for infection. Conclusion. The most common surgical treatment for FNF reported to the AJRR was cementless stem fixation and hemiarthroplasty. The higher revision rates for FNF treatment with THA warrant further investigation. The use of cemented femoral fixation in this patient population may be under-utilized. These data provide a benchmark of US practice for reference and comparison to other practices throughout US and the world

Cementless femoral fixation in total knee replacement has proven to be successful in many studies. There is a recent report by Berger et al, on failure of cementless fixation in a high flexion TKR design. This was with a FiberWire material that had good ingrowth characteristics but was not ideal in terms of immediate fixation. Cementless patellar fixation to date has required a metal backed patella, which has proven to be problematic in most design. For this reason, most surgeons who resurface the patella do so with an all-polyethylene cemented design. The major controversy is cemented tibial fixation. This is problematic when performed with ancillary screw fixation due to screw osteolysis. There are newer designs that have shown promise but cemented tibial fixation remains the gold standard. It is true that early designs of cementless hips were associated with poor results, but newer designs have led to cementless fixation in total hip arthroplasty as the gold standard. It is clear that with newer materials, ancillary biologics and improved design that cementless total knee fixation will eventually prevail. At the present time, the wine needs to stay in the cellar for now

The aim of this study is to present the early results of our department’s experience, about cementless fixation of femoral component in total knee replacement. During the period 1997–2002 from the patients who treated surgically for knee osteoarthratis, 285 were followed up p.o. from 6 months up to 5 years (mean 30 months). They were 246 women and 39 men (mean age 69,4 years), to whom we used unconstrained total knee arthroplasty. For all of them, we didn’t use orthopaedic cement to fix the femoral component and there were no case of patella replacement. All the patients were examined clinically and with x-rays (Knee Society Roentgenographic Evaluation and Scoring System). The answer to the question about the use or not of orthopaedic cement for femoral component fixation is not clear in the international literature. There is the attitude of using cement every time or depending the use of cement on patient’s age and bone quality. On the other hand, many orthopaedic surgeons, like us, never use cement (except for the very osteoporotic bone). There were no cases of femoral component’s loosening in our data. In conclusion, we believe that the cementless fixation of femoral component in total knee replacement offers satisfactory stabilization of the component, the same as the cemented fixation offers, according to the international literature

In properly chosen patients, cementless total knee arthroplasty has achieved success rates equal to cemented designs. The initial variable results of early cementless total knee replacements were a function of design, surgical technique and patient selection. Important design considerations that have enhanced biologic ingrowth include the use of commercially pure titanium with optimal pore size and porosity, and avoidance of porous-coated stems and plugs that cause stress shielding of the bone-implant interface. Factors in surgical technique that enhance bone ingrowth include precise bone cuts that maximize bone-implant contact, and the application of autogenous bone slurry to cut surfaces. Additional factors are restoration of normal alignment, appropriate ligament balance, and the reproduction of the patient's native tibial slope in order to prevent tibial component subsidence. Young and active patients are ideal biological hosts for the use of cementless knee fixation. Their relatively dense cancellous bone and rich blood supply provides for robust purchase for initial fixation and the appropriate milieu for long-term biologic fixation. With increasing life expectancy, this more durable interface is desirable. With avoidance of porous-coated stems and pegs and prevention of fibrous tissue attachment, potential future revisions are more bone-sparing relative to methylmethacrylate fixation. Numerous reports, as well as the authors' published 10- to 14-year results, demonstrate that cementless fixation in appropriately selected patients provides results comparable to cemented TKA, with the advantage of conserving bone stock and eliminating the potential problems of cement fixation

Antibiotic-impregnated cement is frequently used for fixation of total knee prostheses as a measure to prevent postoperative infection. In recent years, more cementless knee prostheses have been implanted especially for younger patients. In 1997 to June 2004, 35044 primary total knee arthroplasties for primary or secondary osteoarthritis were performed in Finland and registered in nationwide arthroplasty register. The patients aged 70 years (range 21–96) on average, and 71.7% were women. During the median follow-up of 39 months (range 0–104), 978 (2.8%) knees were revised. There were 188 (0.58%), 21 (1.09%) and 10 (1.18%) reoperations due to infection after cemented, hybrid and cementless arthroplasties, respectively (p=0.003). In hybrid arthroplasties with cemented tibial component, the septic reoperation rate did not significantly differ from cemented arthroplasties. Instead, the higher number of infections after hybrid arthroplasty was related to use of cementless tibial components (5.3% vs. 0.9%, p< 0.008). In Cox regression model adjusted for age, gender and diagnosis, the hazard ratio for septic reoperation after knee replacement with cementless tibial component was 2.4 (95% CI 1.4–4.1) compared to the cemented alternative. The fixation method did not affect the rate of septic reoperations occurring after the first postoperative year. Cementless fixation of tibial component in primary total knee arthroplasty may associate with an increased risk of early septic reoperation. Until this finding is confirmed in other materials, cementless fixation in primary knee arthroplasty should be used cautiously in patients with increased risk for infection

Purpose of Study. To assess the incidence of radiolucency in cemented and cementless Oxford unicompartmental knee replacement at two years. Introduction. Most unicompartmental knee replacements (UKRs) employ cement for fixation of the prosthetic components. The information in the literature about the relative merits of cemented and cementless UKR is contradictory, with some favouring cementless fixation and others favouring cemented fixation. In addition, there is concern about the radiolucency that frequently develops beneath the tibial component with cemented fixation. The exact cause of the occurrence of radiolucency is unknown but it has been hypothesised that it may suggest suboptimal fixation. Method. Following ethical approval, 62 patients with medial OA were randomised to receive either cemented (n=32) or cementless components (n=30). All patients underwent an identical surgical procedure with either a cemented or cementless Oxford UKR. Patients were assessed clinically by a research physiotherapist and radiologically using screened radiographs. Thirty-eight patients from the trial with follow up of at least two years and well aligned radiographs were identified (cemented n=16, cementless n=22). Results. The patients in the two groups were well matched. Radiological and clinical assessment was at a mean of 2.25 years. There was no significant difference in the clinical scores between the two groups. The median OKS for the cemented group was 43 and for the cementless group was 42.5. Narrow radiolucent lines were seen at the bone-implant interfaces of 63% of the cemented tibial components; partial in 38% and complete in 25%. In the cementless implants, partial radiolucencies were seen in 4.5% and complete radiolucencies in none. The differences are statistically highly significant (p< 0.0001). The lack of radiolucency beneath the cementless tibial components implies satisfactory bone ingrowth and hence fixation. Conclusions. At 2 years the cementless components are well fixed and have similar clinical results to the cemented

Introduction: The information in the literature about the relative merits of cemented and cementless unicompartmental knee replacement (UKR) is contradictory, with some favouring cementless fixation while others favouring cemented fixation. Cemented fixations give good survivorship but there is concern about the radiolucency which frequently develops around the tibial component. The exact cause of the occurrence of radiolucency is unknown but according to some, it may suggest suboptimal fixation. Method: Sixty-two knees (31 in each group) were randomised to receive either cemented or cementless UKR components. The components were similar except that the cementless had a porous titanium and hydroxyappatite (HA) coating. Patients were prospectively assessed by an independent observer pre-operatively and annually thereafter. The clinical assessment included Oxford Knee Score, Knee Society Scores and Tegner activity score. Fluoroscopically aligned radiographs were assessed for thickness and extent of radiolucency under the tibial implant. Results: At one year there were no differences in the clinical outcome between the groups and there were no loose components. No radiolucencies thicker than 1mm were seen. At one year none of the cementless tibias and 30% of the cemented tibias had complete radiolucencies. One out of 31 cementless (3%) and 12 out of 31 cemented (39%) had partial radiolucencies. This difference between these two groups was high significant (p< 0 0001). Conclusions: This study clearly demonstrates that the incidence of radiolucency beneath the tibial component is influenced by component design and method of fixation. With identical designs of tibial component none of the cementless components developed complete radiolucences whereas 30% of the cemented components did. We conclude that HA achieves better bone integration than cement

Introduction: Intramedullary cementless fixation of massive tumor prostheses was developed to combat the high incidence of aseptic loosening in a young population of tumor patients. Its use has also expanded to include reconstruction of failed major knee arthroplasty. Our system uses a hydroxyapatite coated titanium stem in conjunction with a hydroxyapatite collar to obtain fixation. Methods: We present a series of 72 patients (34 females, 38 males) with a mean follow-up of six years (2 months – 14 years). The mean age at the time of surgery was 17 (5 – 77). Within this group, 51 patients had osteosarcomas, 10 had giant cell tumors, eight had Ewing’s sarcoma and one each had malignant fibrous histiocytoma, spindle cell sarcoma and failed total knee arthroplasty. Non-invasive and minimally invasive growing prostheses were used in 33 patients. Results: Nine patients required revision of the prosthesis at a mean of 5.2 years; 5 for aseptic loosening and four for infection. Twelve patients died at a mean of 20 months (1 – 84) post-operatively. Radiological evidence demonstrated remodelling around both the stem and the collar. There was gap closure to the hydroxyapatite coated collar in cases where seating was not complete. Consistent loss of cortical bone around the mid-stem was noted in the first 12 months but remained stable beyond this time frame. Discussion: This study highlights our experience with cementless distal femoral endosprostheses. We demonstrate good results with regard to revision rate, gap closure and osseointegration

Introduction. Few studies are published about total hip arthroplasties (THA) in Parkinson's disease as it is often considered as a contraindication for hip replacement. THA for fracture is reported as a high complication rate surgery. Regarding bone quality these cases are assimilated to elderly patients and cemented implants are generally preferred. However, due to the improved length and quality of life, we face more potential indications for joint replacement. The aim of this study is to report our experience of cementless dual mobility implants for primary THAs for osteoarthrosis and THA revisions focusing on the risks and benefits of surgery. Material and methods. 65 THA were performed in 59 patients (34 men, 25 women, mean age 73 years, 55–79). Mean latest follow-up was 8,3 years (4–14). Indications were 42 primary THA (osteoarthrosis) and 21 revisions (11 recurrent dislocation, 6 acetabular PE wear, 4 femoral loosening). Surgical approach was always antero-lateral. All patients were implanted with the same dual mobility cementless cup. The same cementless corail-type stem was used for primary THA cases. All the cemenless implants were hydroxyapatite coated. The disability caused by the disease was classified according to Hoehn and Yahr. (19 stage 1, 21 stage 2,16 stage 3). Results. 2 patients were lost for follow-up before 2 years. general complications were 3 pulmonary infection, 7 urinary tract infection, 12 cognitive impairment and 2 sacral pressure ulcer. A post-op. wound infection (E Coli) required an early revision in 2 cases without secondary consequencies (7 and 9 years follow-up). We did not observe early or late THA dislocation except in one case at 9 years follow-up (intraprosthetic dislocation due to an increase of ilio psoas muscle retraction requiring a revision of the dual mobility mechanism). We did not observe loosening cases of the cementless cup. 4 patients fell and fractured the femur. The cementless cup was not affected. 10 patients died. Good to excellent pain relief was achieved in 53/57cases at 2 years and in 40/47 cases at latest follow-up. The progression of neurological disability was observed in most of cases. At the latest follow-up for the 47 remaining patients, we had 5 stage 1, 12 stage 2, 21 stage 3,9 stage 4. Discussion. According to literature infection and dislocation are the main concerns for THA in Parkinson patients. This study does not report any trauma cases; this may explain the rather good results on a mean follow-up to more than 8 years. Nevertheless progression of Parkinson's disease is the rule, with significant disability or even death (10 /57 cases). Cementless fixation is possible even on the acetabular side. The poor bone quality of these patients was not an argument against hydroxyapatite coated implants. Conclusion. THA in Parkinson's disease is a challenging surgery due to associated comorbidity. For all patients the functional status improved in the early follow-up and declined with the disease progression. Cementless dual mobility cups and femoral stems can be used with a very low rate of mechanical complication

Unicompartmental Knee Replacement (UKR) is associated with fewer complications, faster recovery and better function than Total Knee Replacement (TKR). However, joint registries demonstrate a higher revision rate in UKR, limiting its use. Currently most UKRs are cemented and performed using a minimally invasive technique. In joint registries, common reasons for revision include aseptic loosening and pain. These problems could potentially be addressed by using cementless implants, which may provide more reliable fixation. The objectives of this study were to compare the quality of fixation (determined by the incidence and appearance of radiolucencies), and clinical outcomes of cemented and cementless UKR at five years. A randomised controlled trial was established with 63 knees (62 patients) randomised to either cemented (32 patients) or cementless UKR (30 patients). Fixation was assessed with fluoroscopic radiographs aligned to the bone-implant interface at one and five years. Outcome scores were collected pre-operatively and at one, two and five years, including Oxford Knee Score (OKS), American Knee Society Score, objective and functional (AKSS-O/F) and Tegner Activity Scale (TAS), expressed as absolute scores and 0–5 year change (δ) scores. Four patients died during the study period. There were no revisions. Mean operative time was 11 minutes shorter in the cementless group (p=0.029). At five years, there was no significant difference in any outcome measure except AKSS-F and δAKSS-F which were significantly better in the cementless group (both p=0.003). There were no femoral radiolucencies in either group. There were significantly more tibial radiolucencies in the cemented group (20/30 vs 2/27, p< 0.001). There were nine complete radiolucencies in the cemented group and none in the cementless group (p< 0.001). Cementless fixation provides improved fixation at five years compared to cemented fixation in UKR, maintaining equivalent or superior clinical outcomes with a shorter operative time and no increase in complications

Introduction: The new anatomical adapted stem system OptanTM (Zimmer) is presented, showing the first mid-term-results for cemented and cementless fixation. Its cross-section in the proximal area corresponds with its antetorsion, anteversion and helitorsion, to the 3D-morphology of the proximal femur. Material and Methods: 313 Optan stems (175 cemented, 148 cementless) were implanted in 306 patients (mean age 62.1 y. (20–74 y.), m/f-ratio 0,8). The clinical and radiological parameters for calculation of Harris Hip Score (HHS), Merle d’Aubigné (MD), WOMAC and periprosthetic bone reaction (Gruen et al.) were recorded. An implant migration analysis using two different biplanar radiographic digital measurement systems (DMA, UMA) was done also. Results: The clinical results for latest follow up examination (5 and more y.p.o.) for cementless (cemented) Optan are: HHS mean (m) 97.6, standard deviation (SD) 7.32 (m 95.1, SD 9.85), MD m 17.6, SD 1.04 (m 17.1, SD 1.48), WOMAC m 1.44, SD 1.56 (m 1.75, SD 1.62). Cemented implantation shows a stable radiographic follow up regarding full cement mantle without any periprosthetic bone adaptations. The SD for the varus-valgus angle rises proportional to the thickness of the cement layer. Only little flattening of the calcar cortical bone (Z7b) could be seen in both, cemented and cementless Optan 2–3 years p.o.. No stem migration was evident in both fixation principles. No relevant osteolyses and cortical bone hypertrophies could be seen. 12 dislocations (closed reposition), 2 femoral fissures (all while cementless fixation), 2 septic loosenings and 1 aseptic loosening were documented till now. Radiographic results of cementless stem show a low rate (29,1%) of secondary endostal reactive line formation in the distal part of the stem (Z3,4,5) beginning 6–12 month postoperative, especially when drilling of femoral bone canal was done. When the distal part of the stem (Z3,5) was fixed directly to cortical bone little hypertrophy of the cortical bone gets relevant 4–5 years p.o. in a few cases. Conclusions: Compared with other anatomical stems the cementless Optan shows excellent midterm results. The clinical results of the cemented fixation are not quite so good, this may be related to the older mean age of the patients with cemented stem fixation. Among other things, the development of the Optan-stem had the aim, to make an interoperative change of fixation technique easier. Using the same stem design the decision about the fixation type can be made intraoperatively in the last second

Introduction: Most unicompartmental knee replacements (UKRs) employ cement for fixation of the prosthetic components to the bone. The information in the literature about the relative merits of cemented and cementless UKR is contradictory, with some favouring cementless fixation while others favouring cemented fixation. There is concern about the radiolucency which frequently develops around the tibial component with cemented fixations. The exact cause of the occurrence of radiolucency is unknown but according to some, it may suggest suboptimal fixation. Method: Following ethical approval, 62 patients with medial OA were randomised to receive either cemented (n=31) or cementless components (n=31). All patients underwent identical surgical procedure with either a cemented or cementless Oxford UKR. Patients were assessed clinically and radiologically. The x-rays were taken with an image intensifier (I.I.). The position of the I.I. was adjusted until it was perfectly aligned with the tibial bone-implant interface thereby allowing accurate assessment of presence and extent of the radiolucency. Results: The patients in the two groups were well matched. There was no significant difference in the clinical scores between the two groups. The mean OKS for the cemented group was 40 (± 8.3) and 42 (± 4.6) for cementless group. Narrow radiolucent lines were seen at the bone-implant interfaces of 75% of the cemented tibial components; partial in 43% and complete in 32%. In the cementless implants, partial radiolucencies were seen in 7% and complete radiolucencies in none. The differences are statistically highly significant (p< 0.0001) and imply satisfactory bone ingrowth into the cementless implants. Conclusions: The method of fixation influences the incidence of radiolucency. With identical designs, no patient with cementless components developed any complete radiolucency. The observation raises the question as to whether cementless rather than cemented components should be routinely used for UKR

Abstract

Experience has demonstrated in the hip and knee, related to total joint replacement arthroplasty, polymethyl methacrylate cement fixation can provide problems in terms of loosening, fragmentation, particulate wear and ultimate failure. These same problems have been recognised in total shoulder arthroplasty related to cement fixation of the glenoid. While cement fixation of the humeral component has proven much less problematic, there has been a swelling towards avoidance of using cement to secure the humeral component for fear of difficulty if revision is required. Surprisingly, with the high incidence of lucent lines, bone resorption and frank loosening, representing the most common source of failure in total shoulder arthroplasty, cementless fixation of the glenoid has not been, until now, embraced. The advent of reverse total shoulder arthroplasty has demonstrated the ability for secure cementless fixation to provide long-lasting secure implant retention in implants which have inherently higher shear and stress forces passing through the implant/bone interface. In anatomic total shoulder arthroplasty a woven tantalum anchor (Trabecular Metal) has proven to demonstrate secure cementless fixation as well. This presentation will discuss the use of trabecular metal anchored glenoid implants with and without additional screw fixation for anatomic and convertible reverse arthroplasty baseplates. Avoidance of complications with successful long-lasting outcomes requires meticulous surgical attention to detail

Introduction and Aims: The standard treatment for an infected total hip replacement involves removal of all foreign material and re-implantation in either one or two stages with antibiotic cement. This study has investigated the use of cementless reconstruction in infected hip arthroplasties to determine if there is a difference in the re-infection rate.

Method: Thirteen patients (three females and 10 males) with an average age of 67 have been followed-up prospectively after revision hip surgery for infection. Removal of the prosthesis was followed by six weeks intravenous antibiotics and in some cases a period of oral therapy. Reconstruction was undertaken at a median of four months post Girdlestone’s arthroplasty, with the exception of a one-stage exchange for medical reasons. Cementless titanium femoral components were used in all revisions and titanium acetabular components where applicable. Allograft and cage reconstruction were employed for major pelvic defects.

Results: Patients have been followed-up for an average of 58 months (range 12–96 months), with no loss to follow-up. Bacteria were cultured from eleven (11) of the thirteen (13) patients and the other two were clinically septic. Bacteria cultured included MRSA, Staph. Aureus, E.Coli and Strep. Faecalis. All prostheses remain in situ with improvement in both Charnley and Oxford hip scores. No recurrence of infection has been documented clinically or radiologically and no component is loose.

Conclusion: Debate still exists about the merits of one vs. two-stage reconstruction for infected hip arthroplasty. This series with mid-term follow-up demonstrates that cementless reconstruction for infected hip arthroplasty is successful in providing an infection-free stable revision.

Introduction

Biological fixation through bone ingrowth and ongrowth to implants can be achieved with a variety of surface treatments and technologies. This study evaluated the effect of two different three dimensional surface coatings for CoCr where porosity was controlled through the use of different geometry of CoCr beads in the sintering process.

Background

The acknowledged benefit of the direct anterior (DA) approach is early functional return. Most surgeons in the U.S. use cementless femoral replacement given the negative track record of some cemented designs. However, delayed osseointegration of a femoral stem typically seen in older patients with poor bone quality will delay recovery, diminishing the benefits of the DA approach. Registry studies have shown a higher revision rate and complications in this patient population leading to a renewed interest in cemented fixation.

Introduction: 3–5 year follow up results of the new anatomical adapted stem system OptanTM (Zimmer) are presented. Its cross-section in the proximal area corresponds with its antetorsion, anteversion and helitorsion, to the 3D-morphology of the proximal femur. Philosophy and aim of the cementless Optan-stem is a proximal fixation and force transmission in the femoral bone.

Material and Methods: Between July 1999 and Dec. 2001 242 Optan stems (122 cemented, 120 cementless) were implanted in 221 patients (mean age 62.1 y. (20–74 y.), m/ f-ratio 0,8). The clinical and radiological parameters for calculation of Harris Hip Score (HHS), Merle d’Aubigné (MD), WOMAC, periprosthetic bone reaction (Gruen et al.) and periarticular heterotopic bone formation (Brooker et al.) were recorded. An implant migration analysis using two different biplanar radiographic digital measurement systems (DMA, UMA) was done also.

Results: The clinical results for latest follow up examination (3–5 y.p.o.) for cementless (cemented) Optan are: HHS mean (m) 97.6, standard deviation (SD) 7.32 (m 95.1, SD 9.85), MD m 17.6, SD 1.04 (m 17.1, SD 1.48), WOMAC m 1.44, SD 1.56 (m 1.75 ,SD 1.62). Radiographic results of cementless stem show a low rate (29,1%) of secondary endostal reactive line formation in the distal part of the stem (Z3,4,5) beginning 6–12 month postoperative, especially when drilling of femoral bone canal was done. When the distal part of the stem (Z3,5) was fixed directly to cortical bone little hypertrophy of the cortical bone gets relevant 4–5 years p.o. in a few cases. Cemented implantation shows a stable radiographic follow up regarding cement mantle without any periprosthetic bone adaptations. The SD for the varus-valgus angle rises proportional to the thickness of the cement layer. Only little flattening of the calcar cortical bone (Z7b) could be seen in both, cemented and cementless Optan 2–3 years p.o.. No stem migration was evident in both fixation principles. No relevant osteoly-ses and cortical bone hypertrophies could be seen. 12 dislocations (closed reposition), 3 femoral fissures (all while cementless fixation), 3 septic loosenings and no aseptic loosening were documented till now.

Conclusions: Compared with other anatomical stems the cementless Optan shows similar excellent clinical mid-term results. The results of the cemented fixation are not quite so good, this may be related to the older mean age of the patients with cemented stem fixation. Till now, the radiographic results of cementless Optan doesn’t seem to contradict the philosophy of attempted physiological proximal force transmission to the femur. Among other things, the development of the Optan-stem had the aim, to make an interoperative change of fixation technique easier. Using the same stem design the decision about the fixation type can be made intraoperatively.

The cementless Oxford unicompartmental knee replacement has been demonstrated to have superior fixation on radiographs and a similar early complication rate compared with the cemented version. However, a small number of cases have come to our attention where, after an apparently successful procedure, the tibial component subsides into a valgus position with an increased posterior slope, before becoming well-fixed. We present the clinical and radiological findings of these six patients and describe their natural history and the likely causes. Two underwent revision in the early post-operative period, and in four the implant stabilised and became well-fixed radiologically with a good functional outcome.

This situation appears to be avoidable by minor modifications to the operative technique, and it appears that it can be treated conservatively in most patients.

Cite this article: Bone Joint J 2014;96-B:345–9.