Observed Component Years Research Articles

Five- and ten-year follow-up of medial unicompartmental knee arthroplasties in obese and non-obese patients.

The aim of this study was to determine whether obesity had a detrimental effect on the long-term performance and survival of medial unicompartmental knee arthroplasties (UKAs). This study reviewed prospectively collected functional outcome scores and revision rates of all medial UKA patients with recorded BMI performed in Christchurch, New Zealand, from January 2011 to September 2021. Patient-reported outcome measures (PROMs) were the primary outcome of this study, with all-cause revision rate analyzed as a secondary outcome. PROMs were taken preoperatively, at six months, one year, five years, and ten years postoperatively. There were 873 patients who had functional scores recorded at five years and 164 patients had scores recorded at ten years. Further sub-group analysis was performed based on the patient's BMI. Revision data were available through the New Zealand Joint Registry for 2,323 UKAs performed during this time period. Obese patients (BMI > 30 kg/m2) were 3.1 years younger than non-obese patients (BMI < 30 kg/m2) at the time of surgery (mean age of obese patients 65.5 years (SD 9.7) and mean age of non-obese patients 68.6 years (SD 10.1)). Preoperatively, obese patients tended to have significantly lower functional scores than non-obese patients, which continued at five and ten years postoperatively. At these timepoints, obese patients had significantly lower scores for most PROMs measured compared to non-obese patients. However, there was no significant difference in the improvement of any of these scores after surgery between obese and non-obese patients. There was no significant difference in revision rates between obese and non-obese patients at any time. All-cause revision rate for obese patients was 0.73 per 100 observed component years compared to 0.67 in non-obese patients at ten years. There was also no significant difference in the aseptic loosening rate between groups. Our study supports the use of UKAs in obese patients, with similar benefit and survival compared to non-obese patients at ten years.

Implant breakage after shoulder arthroplasty: a systematic review of data from worldwide arthroplasty registries and clinical trials

BackgroundImplant breakage after shoulder arthroplasty is a rare complication after aseptic loosening, infection or persistent pain, resulting in malfunction of the components requiring revision surgery. This correlates with a high burden for the patient and increasing costs. Specific data of complication rates and implant breakage are available in detailed arthroplasty registries, but due to the rare occurrence and possibly underestimated value rarely described in published studies. The aim of this systematic review was to point out the frequency of implant breakage after shoulder arthroplasty. We hypothesized that worldwide arthroplasty registry datasets record higher rates of implant breakage than clinical trials.MethodsPubMed, MEDLINE, EMBASE, CINHAL, and the Cochrane Central Register of Controlled Trials database were utilized for this systematic review using the items “(implant fracture/complication/breakage) OR (glenoid/baseplate complication/breakage) AND (shoulder arthroplasty)” according to the PRISMA guidelines on July 3rd, 2023. Study selection, quality assessment, and data extraction were conducted according to the Cochrane standards. Case reports and experimental studies were excluded to reduce bias. The breakage rate per 100,000 observed component years was used to compare data from national arthroplasty registries and clinical trials, published in peer-reviewed journals. Relevant types of shoulder prosthetics were analyzed and differences in implant breakage were considered.ResultsData of 5 registries and 15 studies were included. Rates of implant breakage after shoulder arthroplasty were reported with 0.06–0.86% in registries versus 0.01–6.65% in clinical studies. The breakage rate per 100,000 observed component years was 10 in clinical studies and 9 in registries. There was a revision rate of 0.09% for registry data and 0.1% for clinical studies within a 10-year period. The most frequently affected component in connection with implant fracture was the glenoid insert.ConclusionClinical studies revealed a similar incidence of implant failure compared to data of worldwide arthroplasty registries. These complications arise mainly due to breakage of screws and glenospheres and there seems to be a direct correlation to loosening. Periprosthetic joint infection might be associated with loosening of the prosthesis and subsequent material breakage. We believe that this analysis can help physicians to advise patients on potential risks after shoulder arthroplasty.Level of evidenceIII.

Survivorship, clinical outcomes and indications for revision in uncemented unicompartmental knee arthroplasty: systematic review.

Modern uncemented unicompartmental knee arthroplasty (UKA) relies on the mechanics of the implant design and a biological bond at the bone-implant interface to create a secure fixation of its components. The aim of this systematic review was to determine implant survivorship, clinical outcomes and indications for revision in uncemented UKAs. A search strategy was employed using keywords related to UKAs and uncemented fixation to identify suitable studies. Both prospective and retrospective studies with a minimum of two year mean follow-up were included. Data was gathered on study design, implant type, patient demographics, survivorship, clinical outcome scores and the indications for revision. Methodological quality was assessed using a ten-point risk of bias scoring tool. Eighteen studies were included in the final review. The mean follow-up of studies ranged between 2-11 years. The primary outcome of survival demonstrated 5 year survivorship ranged between 91.7-100.0% and 10-year survivorship between 91.0-97.5%. Clinical and functional outcome scores were found to be excellent in the majority of studies with the remaining reporting good results. Revisions represented 2.7% of the total operations performed. There were 145 revisions with an overall revision rate of 0.8 per 100 observed component years. Osteoarthritis disease progression (30.2%) and bearing dislocations (23.8%) were the most common causes of implant failure. This review finds uncemented UKAs demonstrate comparable survivorship, clinical outcomes and safety profile to cemented UKAs to consider this fixation a suitable alternative in clinical use.

FIVE- AND TEN-YEAR FOLLOW-UP OF UNICOMPARTMENTAL KNEE ARTHROPLASTIES IN OBESE PATIENTS

Due to shorter hospital stays and faster patient rehabilitation Unicompartmental Knee Replacements (UKR) are now considered more cost effective than Total Knee Joint Replacements (TKJR). Obesity however, has long been thought of as a relative contraindication to UKR due to an unproven theoretical concern of early loosening.This study is a retrospective review of patient reported outcome scores and revision rates of all UKR with recorded BMI performed by the Canterbury District Health Board (CDHB) from January 2011 and September 2021. Patient reported outcome scores were taken preoperatively, at 6 months, 1 year, 5 years and 10 years post operatively. These included WOMAC, Oxford, HAAS, UCLA, WHOQOL, normality, pain and patient satisfaction. 873 patients had functional scores recorded at 5 years and 164 patients had scores recorded at 10 years. Further sub-group analysis was performed based on patient BMI of &lt;25, 25-30, 30-35 and &gt;35. Revision data was available for 2377 UKRs performed in Christchurch during this period.Both obese (BMI &gt;30) and non-obese (BMI &lt;30) patients had significantly improved post-operative scores compared to preoperative. Pre-operatively obese patients had significantly lower functional scores except for pain and UCLA. All functional scores were lower in obese patients at 5 years but this did not meet minimum clinical difference. At 10 years, there was significantly lower HAAS, satisfaction and WOMAC scores for obese patients but no difference in Oxford, normality, WHOQOL, UCLA and pain scores. There was no significant difference in the improvement from pre-operative scores between obese and non-obese patients. All cause revision rate for obese patients at 10 years was 0.69 per 100 observed component years compared to 0.76 in non-obese. This was not statistically significant.Our study proves that UKR is an excellent option in obese patients with post-operative improvement in functional scores and 10 year survivorship equivalent to non-obese patients.

Medial malleolar osteotomy for the correction of tibiotalar varus deformity during total ankle arthroplasty: Results in 95 ankles

BackgroundThe importance of deformity correction before or during total ankle replacement (TAR) has been recognized for a long time. Our results of TAR, combined with medial malleolar lengthening osteotomy, for the reconstruction of osteoarthritic ankles with varus deformity are hereby reported. MethodsAll ankles in which a medial malleolar osteotomy was performed during implantation of an ankle prosthesis during the period 1998–2018 were filtered out of our database. Preoperative coronal talar alignment was evaluated by measuring the angle between the tibial shaft and talar dome on the weightbearing mortise ankle radiograph. Patient-reported outcomes were measured with the Foot and Ankle Outcome Score (FAOS) and the Foot and Ankle Ability Measure (FAAM). A Kaplan-Meier survival curve was constructed and the number of revisions per 100 observed component years was calculated for interprosthetic comparison. ResultsA total of 95 TARs were included, consisting of the Alpha Ankle Arthroplasty (n = 22); Buechel-Pappas (n = 14) and the Ceramic Coated Implant Evolution (n = 59) prostheses. The preoperative average talar angle in these ankles was 12.4 degrees varus. In 33% (31/95) corrective procedures, in addition to the medial malleolar osteotomy, were performed. A reoperation rate of 44% (42/95) was found, including 28 revisions (revision rate 29% (4% septic; 25% aseptic) at an average follow-up of 5.9 years, resulting in a survival of 0.69 for the total cohort at 10 years of follow-up.At an average follow-up of 6.6 years the average FAOS scores were: FAOSsymptoms 66, FAOSpain 73, FAOSfunction 78, FAOSsport 45 and FAOSquality of life 56 respectively. The FAAMadl score averaged 64. ConclusionThis is the largest cohort of TAR combined with medial malleolar osteotomy to date. A 29% revision rate at 5.9 years of average follow-up compares unfavorably with regular cohort studies and with most other results in varus-deformed ankles. Scores on the FAOS and FAAM are comparable to those obtained in regular cohorts with similar length of follow-up. TAR in varus-deformed ankles necessitating medial malleolar osteotomy has an even higher failure rate than regular TAR. Obtaining a stable prosthesis with a neutrally-aligned hindfoot at the end of the procedure is of paramount importance. Level of evidenceIV.

Revision Rates After Total Ankle Replacement: A Comparison of Clinical Studies and Arthroplasty Registers.

The aim of this study was to assess the outcome of total ankle replacement (TAR) regarding revision rates by comparing clinical studies of the last decade to data displayed in arthroplasty registers. The secondary aim was to evaluate whether dependent clinical studies show a superior outcome to independent publications. Additionally, revision rates of mobile bearing implants (MB-TARs) were compared to those of fixed bearing implants (FB-TARs). Clinical studies on TARs between 2010 and 2020 were systematically reviewed, with the endpoint being a revision for any reason. The parameter "revision rate per 100 observed component years (CYs)" was calculated for each publication. The pooled revision rate for clinical studies was compared to the data reported in arthroplasty registers. In a second step, revision rates were subdivided and analyzed for independent and dependent publications and for FB-TARs and MB-TARs. A total of 43 publications met the inclusion criteria comprising 5806 TARs. A revision rate of 1.8 per 100 observed CYs was calculated, corresponding to a 7-year revision rate of 12.6%. The 3 arthroplasty registers included showed revision rates ranging from 8.2% to 12.3% after 7 years. No significant difference between dependent and independent publications nor between FB-TARs and MB-TARs was detected. Revision rates of clinical studies and arthroplasty registers are comparable. Surgeons can compare their own revision rates with those from this study. Dependent studies do not seem to be biased, and no superiority for one bearing type can be described. Level III, systematic review of level III studies.

Functional outcomes and complications following convertible primary total elbow arthroplasty: A single surgeon series.

The data on convertible total elbow arthroplasty are limited and primarily based on multiple centre/multiple surgeon series. The aim of this study was to report the mid-term functional outcomes, radiological findings, complications and survivorship of the Latitude total elbow arthroplasty performed by a single surgeon. The study included 13 patients (10 females, mean age of 72 years and varying indications) over eight years. The Oxford Elbow Score (OES), Mayo Elbow Performance Score (MEPS), range of movements (ROM), Subjective Elbow Value (SEV), satisfaction score (SS) and the revision rate of the implant per 100 observed component years (OCY) were assessed. The mean follow-up was 5.9 years (3-10 years). The Oxford Elbow Score/Mayo Elbow Performance Score improved from 15 to 42 (p value < 0.005)/26% to 93% (p value < 0.005) respectively. The arc of extension-flexion/supination-pronation improved from 63° to 106° (p = 0.00002)/123° to 142° (p = 0.32) respectively. The Subjective Elbow Value/Satisfaction Score was 83/98 respectively. There was one re-operation for a deep infection. There were no radiologic signs of loosening and the revision rate was 0.15 per 100 observed component years. With careful patient selection, convertible total elbow arthroplasty provides patients with good to excellent outcomes and substantial improvements in the range of movements.

Cemented or uncemented acetabular fixation in combination with the Exeter Universal cemented stem.

To compare long-term survival of all-cemented and hybrid total hip arthroplasty (THA) using the Exeter Universal stem. Details of 1,086 THAs performed between 1999 and 2005 using the Exeter stem and either a cemented (632) or uncemented acetabular component (454) were collected from local records and the New Zealand Joint Registry. A competing risks regression survival analysis was performed with death as the competing risk with adjustments made for age, sex, approach, and bearing. There were 61 revisions (9.7%; 0.82 revisions/100 observed component years, (OCYs)) in the all-cemented group and 18 (4.0%; 0.30/100 OCYs) in the hybrid group. The cumulative incidence of revision at 18 years was 12.1% for cemented and 5.2% for hybrids. There was a significantly greater risk of revision for all-cemented compared with hybrids (unadjusted sub-hazard ratio (SHR) 2.44; p = 0.001), and of revision for loosening, wear, or osteolysis (unadjusted SHR 3.77; p < 0.001). After adjustment, the increased risk of all-cause revision did not reach significance at age 70 years and above. The advantage for revision for loosening, wear, and osteolysis remained at all ages. This study supports the use of uncemented acetabular fixation when used in combination with the Exeter stem with improved survivorship for revision for aseptic loosening, wear, and osteolysis at all ages and for all-cause revision in patients less than 70 years. Cite this article: Bone Joint J 2020;102-B(4):414-422.

Influence of Preoperative Tibiotalar Alignment in the Coronal Plane on the Survival of Total Ankle Replacement: A Systematic Review.

It remains controversial whether significant preoperative tibiotalar varus and valgus deformity should be contraindications for total ankle replacement (TAR). The primary aim of this systematic review was to analyze the influence of preoperative tibiotalar varus and valgus alignment on the survival of TAR. The databases MEDLINE and Embase were searched from onset through September 2018. Two authors performed study selection and data extraction using a predefined data extraction tool. Implant survival in the alignment groups was reported as "revisions per 100 component years." Additional procedures, complications, and revisions were also reported. Assessment of the methodological quality was performed using the Newcastle-Ottawa Scale (NOS). In total, 17 studies were considered eligible, in which a total of 1692 TARs were included from 1627 patients. The weighted mean follow-up was 52.4 (range, 1-147) months. The neutral alignment group included 711 TARs, the varus group included 545 TARs, and the valgus group included 332 TARs. Total revisions were 52, 37, and 36 in the preoperative tibiotalar neutral, varus, and valgus alignment groups, respectively. Revisions per 100 observed component years were 1.6, 1.7, and 2.5 in the preoperative tibiotalar neutral, varus, and valgus alignment groups, respectively. A total of 129 complications and 447 additional procedures were reported in 601 TARs. There was a strong indication that preoperative varus alignment in the coronal plane had a comparable implant survival to neutral alignment. Preoperative valgus alignment demonstrated a more negative influence on implant survival. Level III, systematic review.

Does surgical approach affect early outcomes following primary total hip replacement in obese patients?

The aim of this study was to assess whether obese patients undergoing primary total hip replacement (THR) via a posterior approach had superior revision rates and Oxford Hip Scores (OHS) compared to those via a lateral approach. This is a retrospective cohort study using prospective data from the New Zealand Joint Registry applying STROBE and RECORD guidelines. Patients undergoing THR since 2010 were stratified by body mass index (BMI) into obese (BMI 30-39 kg/m2), and morbidly obese (BMI ⩾40 kg/m2) groups. All-cause revision rates, and 6-month OHS post-surgery were compared between groups. Multivariate analysis was performed. 12,109 unilateral THRs in obese patients were identified. The mean follow-up was 2.8 years (range 0.01-6.95 years). Univariate analysis in the BMI ⩾ 40 group showed the posterior approach had a significantly lower all-cause revision rate (0.99/100 observed component years (ocys); 95% CI, 0.65-1.44/100 ocys) than the lateral approach (1.71/100 ocys (95% CI, 0.98-2.77/100 ocys), p < 0.05). There was no significant difference in dislocation rates between the surgical approaches. OHS was statistically higher in the posterior approach group in BMI 30-39 patients (p < 0.001) but not clinically significant. Multivariate analysis showed femoral head size significantly influenced all-cause revision rates and mitigated against the increased risk associated with the surgical approach. The choice of surgical approach in obese patients conveys no advantage in overall revision rates in the short-term. Choosing an appropriate size of femoral head may be of greater importance than choice of surgical approach for obese patients in primary THR.

Unicompartmental knee arthroplasties in Hong Kong: 15 years of experience in a teaching hospital.

Osteoarthritis (OA) of the knee is a growing problem in an aging population. Unicompartmental knee arthroplasties (UKA) have been used for management of isolated OA of the medial tibiofemoral joint. This is the first study on the usage of UKA in Hong Kong. Retrospective analysis of all patients undergoing medial compartment UKA in a tertiary referral center since 2003. Preoperative and postoperative International Knee Society Knee Scores (KSKS) and Knee Societal Functional Assessment (KSFA) scores, range of motion, flexion deformity, and lower limb mechanical alignment were measured. Statistical analysis using paired sample t-tests was performed. Revision operations, rate of revisions, and causes of failure were analyzed. Univariate and multivariate logistic regression analyses of risk factors for revision operation were performed against patient demographics, type of prosthesis, postoperative alignment, and degree of correction. There were 94 UKA performed with an average follow-up of 4.3 years (range: 0.5-15.2 years). The KSKS and KSFA scores improved from 54.5 and 54.0 to 85.6 and 64.5 ( p < 0.01), respectively. There was no significant improvement in the range of motion ( p = 0.87) and fixed flexion deformity ( p = 0.14). Mechanical alignment improved from 172.1° to 174.9° varus postoperatively ( p < 0.01). Six cases required revision operation with a revision rate of 1.50 per 100 observed component years. Causes of revision included two cases of tibial tray loosening and one case each of progressive OA, mechanical failure, persistent pain, and infection. Logistic regression analysis for risk factors showed no statistical significance. UKA offers good functional improvement but further long-term studies are required to evaluate survivorship.

Second-generation bi-cruciate stabilized total knee system has a lower reoperation and revision rate than its predecessor

IntroductionTotal knee arthroplasty (TKA) can provide pain relief and good long-term results. However, nearly 30% of post-surgical patients are unsatisfied due to persistent pain and functional deficits. A second-generation bi-cruciate stabilized TKA device has a post-cam mechanism with an asymmetric femoral component, a polyethylene insert, and a medially concave and laterally convex shape. The device is designed to provide guided motion, and thus improve knee kinematics by more closely approximating a normal knee. The aim of this study was to evaluate early complication and revision rates of the second-generation device and to compare its clinical performance to the first-generation device.Materials and methodsIn this retrospective, longitudinal, non-concurrent cohort study, 140 TKAs were performed using the second-generation device on 131 patients from 2012 to 2016, and 155 TKAs were performed using the first-generation device on 138 patients from 2009 to 2012. Primary outcomes were occurrence of revisions and reoperations.ResultsThere were 31 reoperations [3.21 per 100 observed component years (OCY)] in 22 (2.28 per 100 OCY) TKAs in the first-generation device cohort compared to five reoperations (1.92 per 100 OCY) in four TKAs (1.54 per 100 OCY) in the second-generation device cohort. The adjusted hazard ratio (HR) was 3.50 (P = 0.0254). There were 21 revisions (2.17 per 100 OCY) in 16 (1.66 per 100 OCY) TKAs in the first-generation device cohort, compared to only three revisions (1.15 per 100 OCY) in two TKAs (0.77 per 100 OCY) in the second-generation device cohort. The adjusted HR was 4.16 (P = 0.0693).ConclusionThe improved design of the second-generation device appears to be associated with a lower risk of reoperation and revision compared to that of the first-generation device.Level of evidenceIII.

Bearing Dislocation and Progression of Osteoarthritis After Mobile-bearing Unicompartmental Knee Arthroplasty Vary Between Asian and Western Patients: A Meta-analysis.

BackgroundImplant survivorship is reported to be lower and complications, particularly bearing dislocation, are reported to be more frequent in Asian than in Western patients with medial knee osteoarthritis (OA) undergoing Oxford® Phase III unicompartmental knee arthroplasty (UKA). To date, however, these complications have not been compared between these groups of patients.Questions/purposesThe purpose of this study was to perform a meta-analysis comparing the standardized incidence rates of (1) all-cause reoperation; (2) reoperation related to bearing dislocation; and (3) reoperation related to progression of lateral compartment arthritis in Asian and Western patients with medial knee OA who underwent Oxford Phase III UKA.MethodsWe searched MEDLINE® (January 1, 1976, to May 31, 2017), EMBASE® (January 1, 1985, to May 31, 2017), and the Cochrane Library (January 1, 1987, to May 31, 2017) for studies that reported complications of Oxford Phase III UKAs. Studies were included if they reported reoperation rates attributable to bearing dislocation and/or progression of lateral knee OA after surgery with this implant. Twenty-seven studies were included in this systematic review and 16 studies with followups > 5 years were included in the meta-analysis. These rates were converted to standardized incidence rate (that is, reoperations per 100 observed component years) based on mean followup and number of involved knees in each study. After applying prespecified inclusion and exclusion criteria, the studies were categorized into two groups, Asian and Western, based on hospital location. Twenty-five studies, containing 3152 Asian patients and 5455 Western patients, were evaluated. Study quality was assessed by the modified Coleman Methodology score (MCMS). Although all studies were Level IV, their mean MCMS score was 66.92 (SD, 8.7; 95% confidence interval [CI], 63.5–70.3), indicating fair quality. Because the heterogeneity of all subgroup meta-analyses was high, a random-effects model was used with estimations using the restricted maximum likelihood method.ResultsThere was no difference in the proportion of Asian patients versus Western patients undergoing reoperation for any cause calculated as 100 component observed years (1.022 of 3152 Asian patients; 95% CI, 0.810-1.235 versus 1.300 of 5455 Western patients; 95% CI, 1.067-1.534; odds ratio, 0.7839; 95% CI, 0.5323-1.1545; p = 0.178). The mean reoperation rate attributable to bearing dislocation per 100 observed years was higher in Asian than in Western patients (0.525; 95% CI, 0.407-0.643 versus 0.141; 95% CI, 0.116-0.166; odds ratio, 3.7378; 95% CI, 1.694-8.248; p = 0.001) Conversely, the mean reoperation rate attributable to lateral knee OA per 100 observed years was lower in Asian than in Western patients (0.093; 95% CI, 0.070-0.115 versus 0.298; 95% CI, 0.217-0.379; odds ratio, 0.3114; 95% CI, 0.0986-0.9840; p < 0.001).ConclusionsAlthough total reoperation rates did not differ in the two populations, reoperation for bearing dislocation was more likely to occur in Asian than in Western patients, whereas reoperation for lateral knee OA progression was more likely to occur in Western than in Asian patients after Oxford Phase III UKA. Although possible explanations for these findings may be hypothesized, additional randomized, prospective comparative studies are needed. However, better survival outcomes after UKA may require consideration of ethnicity and lifestyle choices in addition to traditional surgical technique and perioperative care.Level of EvidenceLevel III, therapeutic study.

The Morscher Press-Fit Acetabular Component: An Independent Long-Term Review at 18-22 Years

BackgroundThere are relatively few 20-year results of uncemented acetabular components, and most of these are modular designs. This study reports the 20-year results of a monoblock press-fit acetabular component. MethodsA total of 122 total hip arthroplasties (111 patients) using the Morscher cup were reviewed at a mean of 19.7 years. The average age at implantation was 57.3 years (range, 36-74 years), and 81 (66%) were men. ResultsTwenty-two patients (25 hips) had died. Seven hips were revised, including 5 acetabular revisions. Six patients (6 hips) declined to participate but were known not to have been revised. The mean Oxford hip score was 41.1 (range, 22-48), and the mean reduced Western Ontario and McMaster Universities Osteoarthritis Index score was 5.7/48 (range, 0-24). Eccentric wear was seen in 13 (15.7%) and major osteolysis in 14 (17%) of 82 surviving hips with radiographs. The all-cause revision rate was 0.32 per 100 observed component years (95% confidence interval [CI], 0.13-0.66). The 20-year Kaplan-Meier survival was 93.4% (CI, 86.6-96.8) for all-cause revisions, 95.5% (CI, 89.4-98.1) for any acetabular revision, and 97.1% (CI, 91.2-99.1) for acetabular aseptic loosening, wear, or osteolysis. ConclusionThe Morscher acetabular component has continued to perform well at 20 years despite using conventional polyethylene with results that match or surpass other cementless acetabulae.

Current concepts, classification, and results in short stem hip arthroplasty.

Various short hip stems have been introduced with differing implant concepts of femoral fixation and implant length. There is a lack of proper classification for short hip stems, with a clear and accepted definition for implant length and extent of bone preservation in the metaphyseal and diaphyseal femur. This study analyzed the length of short hip stems. Stems were divided into collum, partial collum, and trochanter-sparing implants. An additional category was added, trochanter harming, which was defined as interruption of the circumferential integrity of the femoral neck. For all of the femoral components described, the designs were compared, excluding stems with insufficient clinical data. The 15 finally selected stems were classified as collum (1 stem), partial collum (7 stems), trochanter sparing (4 stems), and trochanter harming (3 stems). Mid-term results (>5 years of follow-up) were available for only 3 designs in the partial collum group. Taking into account the results of short-term studies (<5 years of follow-up), the femoral revision rate per 100 observed component years was <1 for most total hip arthroplasties. However, the studies varied greatly regarding level of significance, and short hip stems without published results are available commercially. Short hip stems cannot be circumscribed by a simple length limit. For some designs, clinical data collected from large patient cohorts showed a survivorship comparable to traditional stems. In cases that must be revised, this often can be performed with a conventional primary stem, fulfilling the promise to preserve bone for potential future revisions in younger patients.

Clinical outcome after UKA and HTO in ACL deficiency: a systematic review

In the treatment of medial osteoarthritis secondary to anterior cruciate ligament (ACL) injury there is no consensus about optimum treatment, with both high tibial osteotomy (HTO) and unicompartmental knee arthroplasty (UKA) being viable options. The aim of this review was to compare the outcomes of these treatments, both with or without ACL reconstruction. EMBASE, MEDLINE and the Clinical Trials Registers were searched to identify relevant studies. Studies meeting pre-defined inclusion criteria were assessed independently by two researchers for methodological quality and data extracted. Twenty-six studies involving 771 patients were identified for inclusion. No randomized controlled trials were identified. Seventeen studies reported outcomes following HTO and nine studies reported outcomes following UKA. HTO patients were significantly younger than those receiving UKA, and ACL reconstruction patients were younger than non-reconstructed patients. Treatment with HTO ACL reconstruction had the lowest revision rate (0.62/100 observed component years) but the highest rate of complications (4.61/100 observed component years). Too little data were available to test for differences in outcome between different surgical techniques or prosthesis designs. Limited conclusions about the optimum treatment can be made due to the absence of controlled trials. In patients treated with HTO ACL reconstruction, the high complication rate likely outweighs its minimally superior survival. Outcomes following UKA ACL reconstruction are similar to outcomes for UKA in the ACL intact knee without any increase in complications. As such in patients meeting indications for UKA, UKA ACL reconstruction should be performed with further work required to identify the optimum treatment in other patient groups. IV.

Quality of outcome data in knee arthroplasty

Background and purpose — Recent reports on developer bias in unicondylar knee arthroplasty led to concerns about quality of publications regarding knee implants. We therefore compared revision rates of registry and non-registry studies from the beginning of knee arthroplasty up to the present. We assessed the time interval between market introduction of an implant and emergence of reliable data in non-registry studies. Material and methods — We systematically reviewed registry studies (n = 6) and non-registry studies (n = 241) on knee arthroplasty published in indexed, peer-reviewed international scientific journals. The main outcome measure was revision rate per 100 observed component years. Results and interpretation — For 82% of the 34 knee implants assessed, revision data from non-registry studies are either absent or poor. 91% of all studies were published in the second and third decade after market introduction. Only 5% of all studies and 1% of all revisions were published in the first decade. The first publications on revision rates of total knee arthroplasty (TKA) started 6 years after market introduction, and reliable data were found from year 12 onward in non-registry studies. However, in unicondylar knee arthroplasty (UKA) the first publications on revision rates could be found first 13 years after market introduction. Revision rates of TKA from non-registry studies were reliable after year 12 following market introduction. UKA revision rates remained below the threshold of registry indices, and failed to demonstrate adjustment towards registries.Thus, the superiority of registry data over non-registry data regarding outcome measurement was validated.

Revision rate after short-stem total hip arthroplasty

Background and purpose — The aim of short-stem total hip arthroplasty is to preserve proximal bone stock for future revisions, to improve biomechanical reconstruction, and to make minimally invasive approaches easier. It is therefore being increasingly considered to be a sound alternative to conventional total hip arthroplasty, especially for young and active patients. However, it is still unknown whether survival rates of short-stem hips match current standards. We made a systematic summary of reported overall survival after short-stem total hip arthroplasty.Materials and methods — We conducted a systematic review of English, French, German, and Dutch literature. 2 assessors independently identified clinical studies on short-stem hip arthroplasty. After recalculating reported revision rates, we determined whether each implant had a projected revision rate of 10% or less at 10 years of follow-up or a revision rate per 100 observed component years of 1 or less. Stems were classified as “collum”, “partial collum”, or “trochanter-sparing”.Results and Interpretation — We found 49 studies, or 51 cohorts, involving 19 different stems. There was a large increase in recent publications. The majority of studies included had a follow-up of less than 5 years. We found a large number of observational studies on “partial collum” and “trochanter-sparing” stems, demonstrating adequate survival rates at medium-term follow-up. Clinical evidence from “collum stem” studies was limited to a small number of studies with a medium-term follow-up period. These studies did not show a satisfactory overall survival rate.

Revision of Unicompartmental Arthroplasty to Total Knee Arthroplasty: Not Always a Slam Dunk!

As the number of UKA performed in the world continues to increase, so will the number of failures. A better understanding of the outcomes after revision UKAto TKA is warranted. The objective of this study is to report the outcomes of modern UKA revised to TKA in three US centers. A total of 175 revisions of medial UKA in 168 patients (81 males, 87 females; average age of 66 years) performed from 1995 to 2009 in three institutions and with a minimum of 2-year clinical follow-up were reviewed. Individual joint registries and chart reviews were performed to collect data regarding reasons for revision, type of implants used, and re-revision rates. The average time from UKA to revision TKA was 71.5 months (range 2 months to 262 months). The four most common reasons for failure of the UKA were femoral or tibial loosening (55%), progressive arthritis of the lateral or patellofemoral joints (34%), polyethylene failure (4%) and infection (3%). The average follow-up after revision was 75 months. Nine of 175 knees (4.5%) were subsequently revised at an average of 48 months (range 6 months to 123 months.) The rate of revision was 1.23 revisions per 100 observed component years. The average Knee Society pain and function score increased to 75 and 66, respectively. In the present series, the re-revision rate after revision TKA from UKA was 4.5 % at an average of 75 months or 1.2 revisions per 100 observed component years. Compared to published individual institution and national registry data, re-revision of a failed UKA is equivalent to revision rates of primary TKA and substantially better than re-revision rates of revision TKA. These data should be used to counsel patients undergoing revision UKA to TKA.

Pooled outcome of total hip arthroplasty with the CementLess Spotorno (CLS) system: a comparative analysis of clinical studies and worldwide arthroplasty register data

Our aim was to elucidate the pooled outcome of the CementLess Spotorno (CLS) system in total hip arthroplasty (THA). We compared the outcome of clinical inventor studies, independent clinical studies, and worldwide register data. The main endpoints for analysis were revision rates. Twenty clinical studies were evaluated and, with one exception, overall found revision rates largely in line with register data. Revision rates (revisions per 100 observed component years) range from 0.15 (inventor study) to 0.28 (independent studies) and 0.43 (register datasets). Data of journal publications and register datasets using the CLS system do not differ significantly with respect to revision rates. Only the initial inventor study reports a revision rate three times lower than in pooled worldwide register datasets.