Long-term results of Kinematic Condylar knee replacement. An analysis of 404 knees

Trabecular metal monoblock versus modular tibial trays in total knee arthroplasty: meta-analysis of randomized control trials

PURPOSE

Total knee arthroplasty is one of the significantly evolving procedures with different knee designs available in the market. The continued development of these prosthesis resulted in improvement of the implant survivorship and patient satisfaction. This study is an RCT-based meta-analysis aimed to compare two designs of total knee replacement: the conventional modular and the monoblock trabecular metal tibial trays.

METHODS

This meta-analysis was performed by a literature review according to the PRISMA guidelines. A detailed search of the English literature was done using the PubMed, Medline, CINAHL, Cochrane, Embase, and Google Scholar databases. Only randomized control trials were included in the analysis after ensuring homogeneity. RevMan V.5.0.18.33 (The Cochrane Collaboration, Copenhagen, Denmark) was used to perform the meta-analysis. Extracted outcome measures were Knee Society score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, survivorship, complication rate, and radiostereographic analysis.

RESULTS

Seven randomized control trials with 635 patients were eligible for our analysis after they met our inclusion criteria. Three hundred twelve patients received monoblock tibias, and the other 323 patients received modular tibial trays during their total knee arthroplasty surgeries. There were statistically significant superiority of the modular knees in the functional Knee Society and WOMAC scores at five years (P = 0.003 and 0.05, respectively). The modular design was also more stable on RSA at two years (P < 0.0001).

CONCLUSION

Modular and monoblock tibial trays are comparable knee designs with comparable survivorship and complication rates. However, the modular knees had better mid-term functional outcome and are more stable on radiostereographic analysis.

Osteointegrative Sleeves for Metaphyseal Defect Augmentation in Revision Total Knee Arthroplasty: Clinical and Radiological 5-Year Follow-Up

BACKGROUND

Cementless metaphyseal implant fixation of revision total knee arthroplasty has encouraging early results. We analyzed midterm results and implant survival of osteointegrative augments in Anderson Orthopedic Research Institute (AORI) type 2a, 2b, and 3 defects. Reasons for implant failure were explored and the potential for anatomic joint line reconstruction evaluated.

METHODS

Sixty-seven consecutive patients (68 revision total knee arthroplasties) received cementless metaphyseal sleeves between 2011 and 2014. The mean follow-up was 5.0 years, mean age was 68.5 years, and mean body mass index was 31.4 kg/m². The clinical and radiographic results were determined using established scoring systems. Additionally, the survival rate was calculated and reasons for failure were analyzed.

RESULTS

In 2 patients (4.3%), sleeves had to be removed early postoperatively for deep infection after second-stage reimplantation. With continuously functioning remaining implants, the aseptic survival rate was 93.6%. Cleared up for initial technical issues due to poor bone quality, it is as high as 98%. The scores remained to be significantly improved by 64.8 points (Western Ontario and McMaster Universities Osteoarthritis Index) and 25.8 points (Knee Society score) (P < .001). In 10 patients (29.4%), diaphyseal radiolucencies were observed without suspicion of loosening. The mean joint line was noted to be 0.36 mm lower to the anatomic level.

CONCLUSION

At a mean follow-up of 5.0 years, cementless osteointegrative sleeves for metaphyseal fixation in AORI 2a, AORI 2b, and AORI 3 defects yielded continuous implant fixation even in cases with preceding revisions. The cleared up aseptic survival rate was 98% at 5 years. The modular sleeve design allowed joint line reconstruction near the anatomic level.

Predictive Factors of "Forgotten Knee" Acquisition After Total Knee Arthroplasty: Long-Term Follow-Up of a Large Prospective Cohort

BACKGROUND

In a large prospective cohort, we recently showed that only 66.1% of total knee arthroplasty (TKA) with a perfect outcome according to Knee Society Knee Score was completely forgotten in all everyday activities. The main objective of this study was to identify clinical and orthopedic factors associated with the acquisition of "forgotten knee" (FK).

METHODS

Patients undergoing TKA were enrolled between January 2001 and January 2008. Preoperative medical history, anthropometric data, and clinical data were recorded, and composite scores (Knee Society Score, Lequesne) were assessed. Radiography was performed before and after surgery. At each follow-up, FK acquisition was assessed by a closed question "Does the operated knee feel always normal in all everyday activities?"

RESULTS

We included 510 TKAs performed in 423 patients followed up for a mean of 76.6 ± 28.5 months. On multivariate analysis, depression at baseline and presence of patellar subluxation after surgery were negatively associated with FK acquisition (odds ratio [OR] = 0.28 [95% confidence interval {CI}, 0.13-0.61], P = .001; and OR = 0.31 [0.12-0.79], P = .01, respectively), whereas increased active flexion at last follow-up was positively associated (OR = 1.07 [1.03-1.10], P < .0001). In patients with a perfect outcome (Knee Society Knee Score = 100), preoperative patellar pain, and postoperative patellar subluxation were negatively associated with FK acquisition (OR = 0.41 [0.18-0.93], P = .03 and OR = 0.21 [0.05-0.90], P = .04, respectively). Gender, age, body mass index, preoperative pain and functional limitation, and patellar resurfacing were not significantly related to FK.

CONCLUSION

Depression and patella maltracking may be associated with lack of FK acquisition after TKA, while postoperative increase in flexion may have a positive impact.

Superficial wound infection does not cause inferior clinical outcome after TKA

PURPOSE

Superficial wound infections do not lead to chronic prosthetic joint infection. Therefore, it has been hypothesized that a superficial infection of a surgical wound following a successfully treated TKA does not lead to a lower functional outcome at long-term follow-up. This may be due to early diagnosis and proper treatment without interrupting the rehabilitation programme. The purpose of this study was to support the hypothesis by comparing the functional outcome and health-related quality of life (HRQoL) of superficial infections treated successfully after primary total knee arthroplasty (TKA).

METHODS

In a 3000 prospective TKA cohort, 45 superficial infections were compared to a control group of 629 TKA without complications. The functional outcome, health quality, expectations and revision rate were compared between the study and control groups.

RESULTS

The groups were comparable in terms of demographic values and preoperative scores. The mean follow-up was 74.57 months (SD ± 7.1). No statistical differences were observed relative to functional outcomes at the final follow-up as measured with the Knee Society Score (156.9 vs 168.4; n.s) and range of motion (0.2-114.4 vs 0.7-112.3; n.s). For the HRQoL, no differences in the physical (40.0 vs 40.6; n.s) and mental (43.2 vs 45.8; n.s) SF-36 scores were found. Neither were there differences in post-operative expectations and the revision rate.

CONCLUSIONS

In a long-term follow-up, a different clinical outcome and HRQoL were not obtained after a successfully treated superficial infection following a TKA when compared to a TKA without complications. Based on the findings of the study, additional complications are not anticipated after a successfully treated superficial wound infection in TKA. Therefore, a different follow-up to that of a non-complicated TKA is not recommended when the early post-operative superficial wound infection has been appropriately treated. A superficial infection successfully treated in the acute post-operative period should be considered solved at long-term follow-up.

LEVEL OF EVIDENCE

Therapeutic study, Level III.

Influence of the Medial Knee Structures on Valgus and Rotatory Stability in Total Knee Arthroplasty

BACKGROUND

Precise biomechanical knowledge of individual components of the MCL is critical for proper MCL release during TKA. This study was to define the influences of the deep MCL and the POL on valgus and rotatory stability in TKA using cadaveric knees.

METHODS

This study used six fresh-frozen cadaveric knees. All TKA procedures were performed using a cruciate-retaining TKA with a CT-free navigation system. We did a sequential sectioning on each knee, S1; femoral arthroplasty only, S2; medial half tibial resection with spacer, S3; anterior cruciate ligament cut, S4; tibial arthroplasty, S5; release of the dMCL, S6; release of the POL. The navigation system monitored motion after application of 10 N-m valgus loads and 5 N-m internal and external rotation torques to the tibia at 0°, 20°, 30°, 60°, and 90° of knee flexion for each sequence.

RESULTS

There were no significant differences in medial gaps. Internal rotation angles significantly increased after S2 at 0°, 20°, and 30°, and after S6 at 90° compared with those after S1. External rotation angles significantly increased after S3 at 0°, S4 at 60°, S5 at 0°, 30° and 90°, and after S6 at 30°, 60° compared with those after S1.

CONCLUSION

Significant increases of rotatory instability were seen on release of the dMCL, and then further increased after release of the POL. Surgical approach of retaining the dMCL and POL has a possibility to improve the outcome after primary TKA.

Comparison of clinical outcomes between total knee arthroplasty and unicompartmental knee arthroplasty for osteoarthritis of the knee: a retrospective analysis of preoperative and postoperative results

Background

Excellent results have recently been reported for both total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA), but there have been few reports about which has a better long-term outcome. The preoperative and postoperative results of TKA and UKA for osteoarthritis of the knee were thus compared.

Methods

The results of 48 patients who underwent TKA and 25 patients who underwent UKA were evaluated based on clinical scores and survivorship in the middle long-term period. Preoperative, latest postoperative, and changes in the femoro-tibial angle (FTA), range of motion (ROM), Japanese Orthopedic Association score (JOA score), and Japanese Knee Osteoarthritis Measure (JKOM) were compared. The patients’ mean age was 73 years. The mean follow-up period was 9 years (TKA: mean, 10.5 years; range, 7–12 years; UKA: mean, 9 years; range, 6–11 years).

Results

Preoperative FTA and ROM were significantly higher in the UKA group than in the TKA group. Total changes in all scores were similar among the two groups, as were changes in scores for all JOA and JKOM domains. The cumulative revision rate was higher for UKA than for TKA (7 versus 4 %). Kaplan-Meier survivorship at 10 years was 84 % for UKA and 92 % for TKA.

Conclusions

This clinical study found no significant differences between TKA and UKA, except in long-term survivorship.

"Forgotten knee" after total knee replacement: A pragmatic study from a single-centre cohort

OBJECTIVES

After total knee replacement (TKR), some patients find their operated knee totally natural and can be said to have "forgotten" it, while others, although satisfied with their results, remain conscious of their prosthesis. This is not well assessed on conventional end-points. Since 2001, we have studied the prevalence of "forgotten knee" (FK) after TKR in a prospective pragmatic cohort, with comparison to conventional scores.

METHODS

Patients undergoing TKR were enrolled between January 2001 and January 2008. Preoperative medical history and anthropometric and clinical data were recorded, and composite scores (Knee Society Score (KSS), Lequesne) were assessed. At each follow-up visit, FK acquisition was assessed by the closed question "Do you feel the operated knee to be always normal in all everyday activities?".

RESULTS

Five hundred and eighty-four TKRs in 485 patients were included. Among the TKR, 91.6% were performed for severe osteoarthritis of the knee. FK frequency at a mean 75.8 months' follow-up was 42.9% while 86.1% of TKRs had excellent (KS Knee Score (KSKS)>80) or 34.9% perfect (KSKS=100) outcome. Only 66.1% of the 204 TKRs with perfect outcome on KSKS were reported as FK. Most patients achieved FK within 18 months.

CONCLUSION

In this prospective study, 42.9% of TKRs were considered always forgotten in all everyday activities.

What can be learned from minimum 20-year followup studies of knee arthroplasty?

BACKGROUND

Long-term evaluation of knee arthroplasty should provide relevant information concerning the durability and performance of the implant and the procedure. Because most arthroplasties are performed in older patients, most long-term followup studies have been performed in elderly cohorts and have had low patient survivorship to final followup; the degree to which attrition from patient deaths over time in these studies might influence their results has been poorly characterized.

QUESTIONS/PURPOSES

The purpose of this study was to examine the results at 20-year followup of two prospectively followed knee arthroplasty cohorts to determine the following: (1) Are there relevant differences among the two implant cohorts in terms of revision for aseptic causes (osteolysis, or loosening)? (2) How does patient death over the long followup interval influence the comparison, and do the comparisons remain valid despite the high attrition rates?

METHODS

Two knee arthroplasty cohorts from a single orthopaedic practice were evaluated: a modular tibial tray (101 knees) and a rotating platform (119 knees) design. All patients were followed for a minimum of 20 years or until death (mean, 14.1 years; SD 5.0 years). Average age at surgery for both cohorts was >70 years. The indications for the two cohorts were identical (functionally limiting knee pain) and was surgeon-specific (each surgeon performed all surgeries in that cohort). Revision rates through a competing risks analysis for implants and survivorship curves for patients were evaluated.

RESULTS

Both of these elderly cohorts showed excellent implant survivorship at 20 years followup with only small differences in revision rates (6% revision versus 0% revision for the modular tibial tray and rotating platform, respectively). However, attrition from patient deaths was substantial and overall patient survivorship to 20-year followup was only 26%. Patient survivorship was significantly higher in patients<65 years of age in both cohorts (54% versus 15%, p<0.001 modular tray cohort, and 52% versus 26%, p=0.002 rotating platform cohort). Furthermore, in the modular tray cohort, patients<65 years had significantly higher revision rates (15% versus 3%, p=0.0019).

CONCLUSIONS

These two cohorts demonstrate the durability of knee arthroplasty in older patients (the vast majority older than 65 years). Unfortunately, few patients lived to 20-year followup, thus introducing bias into the analysis. These data may be useful as a reference for the design of future prospective studies, and consideration should be given to enrolling younger patients to have robust numbers of living patients at long-term followup.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Development of an injectable bioactive bone filler cement with hydrogen orthophosphate incorporated calcium sulfate

Calcium sulfate cement (CSC) has emerged as a potential bone filler material mainly because of the possibility of incorporating therapeutic agents. Delivery of the cement through a needle or cannula will make it more useful in clinical applications. However, it was not possible to make CSC injectable because of the inherent lack of viscosity. The present work demonstrates the design development of a viscous and fully-injectable CSC by incorporating hydrogen orthophosphate ions, which does not hamper the biocompatibility of the material. The effect of addition of hydrogen orthophosphate on the rheological properties of the CSC paste was studied using a custom made capillary rheometer. The physicochemical changes associated with cement setting process were examined using X-ray diffraction and Fourier transform infrared spectroscopy and the thermal changes were measured through isothermal differential scanning calorimetry. Micromorphological features of different compositions were observed in environmental scanning electron microscopy and the presence of phosphate ions was identified with energy dispersive X-ray spectroscopic analysis and inductively coupled plasma-optical emission spectroscopy. The results indicated that HPO4 (2-) ions have profound effects on the rheological properties and setting of the CSC paste. Significant finding is that the HPO4 (2-) ions are getting substituted in the calcium sulfate dihydrate crystals during setting. The variations of setting time and compressive strength of the cement with the additive concentration were investigated. An optimum concentration of 2.5 % w/w gave a fully-injectable cement with clinically relevant setting time (below 20 min) and compressive strength (12 MPa). It was possible to inject the optimised cement paste from a syringe through an 18-gauge needle with thumb pressure. This cement will be useful both as bone filler and as a local drug delivery medium and it allows minimally invasive bone defect management.

Gender differences in the morphology of the trochlea and the distal femur

PURPOSE

The objective of this study was to provide a morphologic description of the distal femur and to determine whether there are any gender differences in the shape that might have an important consequence for the design of a femoral component of a total knee prosthesis.

METHODS

Anthropometric data on the distal femur of 200 normal knees were obtained using two-dimensional MRI measurements. In all 18 parameters of the distal femur were measured including the anteroposterior (AP) dimension of femoral condyles, the mediolateral (ML) width of the distal femur at four levels, and the AP dimension and ML width of the trochlea. The aspect ratios between the AP and ML dimensions were calculated to determine whether there is a shape difference between genders.

RESULTS

The female distal femur is significantly smaller in all measured parameters. The mean AP/ML aspect ratio of the female distal femur is significantly larger (p<0.05) at all measured ML levels except that of the anterior edge of the anterior chamfer. The AP dimensions of both the medial and lateral trochlea were significantly greater in men (p<0.001), but AP/ML aspect ratio did not differ between genders.

CONCLUSIONS

We have found that although the female distal femur is relatively narrower (larger AP/ML aspect ratio) than the male in three of the four measured levels, there is no significant difference between genders at the level of the anterior edge of the anterior chamfer. It is at this level that it has been suggested that impingement between soft tissues and an overhanging prosthesis is most likely to be painful. Equally, there were no gender-related differences in the shape of the trochlea. These data therefore do not support the provision of narrow femoral components for TKA for women.

The Rotaglide+ total knee replacement: a comparison of mobile versus fixed bearings

PURPOSE

Mobile-bearing knee replacements were introduced as an alternative to their fixed-bearing counterparts. Movement of the polyethylene insert relative to the tibial tray has been shown to decrease contact stresses, wear and polyethylene-induced osteolysis. The aim of this study is to compare outcomes between mobile and fixed-bearing surfaces of the Rotaglide+ total knee prosthesis.

METHODS

A prospective, partially randomised twin cohort study of 149 Rotaglide+ total knee arthroplasties performed in one unit between September 2000 and January 2005, was carried out. The patients were allocated to a mobile or fixed bearing. The patients were assessed using a pain visual analogue score (VAS), the American Knee Surgeons Score (AKSS) the range of movement, the Oxford Knee Score (OKS) and walking time. Seventy-five patients had mobile-bearing surfaces, and 74 had fixed bearings.

RESULTS

At 5-year follow-up, there was no significant difference between the fixed- and mobile-bearing implants with respect to range of movement [104.7(SD 17.0) vs. 103.6(SD 15.7) degrees]; AKSS [146.6(SD 23.9) vs. 144.1(SD 32.4)]; VAS [3.3(SD 1.2) vs. 3.4(SD 1.3)]; OKS [30.8(SD 9.7) vs. 29.6(SD 10.9)], respectively.

CONCLUSION

This study is the first of its kind to outline the medium-term (≥5 years) outcomes in Rotaglide+ total knee replacements. Its findings reinforce previous research which has shown no discernible difference in clinical outcomes between the 2 groups.

Bacterial contamination of the wound during primary total hip and knee replacement. Median 13 years of follow-up of 90 replacements

BACKGROUND AND PURPOSE

Previous work has shown that despite preventive measures, intraoperative contamination of joint replacements is still common, although most of these patients seem to do well in follow-up of up to 5 years. We analyzed the prevalence and bacteriology of intraoperative contamination of primary joint replacement and assessed whether its presence is related to periprosthetic joint infection (PJI) on long-term follow-up.

PATIENTS AND METHODS

49 primary total hip replacements (THRs) and 41 total knee replacements (TKRs) performed between 1990 and 1991 were included in the study. 4 bacterial swabs were collected intraoperatively during each procedure. Patients were followed up for joint-related complications until March 2011.

RESULTS

19 of 49 THRs and 22 of 41 TKRs had at least 1 positive culture. Coagulase-negative staphylococci and Staphylococcus aureus were the most common organisms, contaminating 28 and 9 operations respectively. Where information was available, bacteria from 27 of 29 contaminated operations were susceptible to the prophylactic antibiotic administered. 13% of samples gathered before 130 min of surgery were contaminated, as compared to 35% collected after that time. 2 infections were diagnosed, both in TKRs. 1 of them may have been related to intraoperative contamination.

INTERPRETATION

Intraoperative contamination was common but few infections occurred, possibly due to the effect of prophylactic antibiotics. The rate of contamination was higher with longer duration of surgery. It appears that positive results from intraoperative swabs do not predict the occurrence of PJI.

Posterior cruciate-retaining versus posterior stabilized total knee arthroplasty: a meta-analysis of randomized controlled trials

PURPOSE

To compare the outcomes between posterior cruciate-retaining and posterior stabilized total knee arthroplasty (TKA) in order to evaluate which approach is superior.

METHODS

Randomized controlled trials (RCTs) comparing posterior cruciate-retaining with posterior stabilized TKA were reviewed which were published up to August 2011. Methodological quality of each included RCT was assessed using the Physiotherapy Evidence Database (PEDro) scale. The relevant data were analysed using Review Manager 5.1. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to determine the quality of the evidence.

RESULTS

Eight RCTs involving 888 patients with 963 knee joints met predetermined inclusion criteria. The postoperative range of motion (ROM) and flexion angle were 11.07° and 2.88° higher for patients with a posterior stabilized TKA than those with a posterior cruciate-retaining TKA, respectively [weighted mean difference (WMD), -11.07; 95% confidence interval (CI), -18.06 to -4.08; p < 0.01 and WMD, -2.88; 95% CI, -5.63 to -0.12; p = 0.04]. No statistical differences were observed between the two designs for knee society pain score, extension angle, 2- and 5-year knee society score, 2- and 5-year knee society function score and complications after primary TKA.

CONCLUSION

Posterior cruciate-retaining and posterior stabilized TKA have similar clinical outcomes with regard to knee function, postoperative knee pain and the other complications. Prosthesis survivorship for both posterior cruciate-retaining and posterior stabilized TKA is satisfactory, and there are no differences between them at short- and middle-term follow-up.

LEVEL OF EVIDENCE

II.

Changes in bone mineral density of the distal femur after total knee arthroplasty: a 7-year DEXA follow-up comparing results between obese and nonobese patients

BACKGROUND AND PURPOSE

Periprosthetic femoral bone mineral density (BMD, g/cm2) decreases after total knee arthroplasty (TKA) as a result of the stress-shielding phenomenon. It is not known whether obesity has an effect on this phenomenon or not. The aim of this study was to assess long-term periprosthetic BMD changes after TKA and compare whether there is a difference between obese and nonobese patients.

METHODS

A total of 69 TKAs in 61 patients were performed, and BMD measurements of the distal femur were followed up to 7 years postoperatively. The patients were divided into two study groups according to their body mass index, and the groups were compared in relation to BMD and functional outcome.

RESULTS

The mean of periprosthetic bone loss during the 7-year follow-up varied from 10.3% to 30.6% depending on the region of interest (p<0.0005). The highest bone-loss rates were detected during the first three postoperative months. A total of 26 patients were categorized as obese with a body mass index value of ≥30 kg/m2. The obese patients' total periprosthetic BMD was higher at both baseline (8.6%) and 7 years after operation (p=0.05) (15.2%).

CONCLUSION

Periprosthetic bone loss around the femoral component continued for up to 7 years postoperatively. The loss of bone density was not associated with any negative clinical outcome in this study, but periprosthetic bone loss was of a smaller quantity in the obese which is probably due to higher weight induced stresses on bone.

Trabecular metal in total knee arthroplasty associated with higher knee scores: a randomized controlled trial

BACKGROUND

Porous tantalum is an option of cementless fixation for TKA, but there is no randomized comparison with a cemented implant in a mid-term followup.

QUESTIONS/PURPOSES

We asked whether a tibial component fixed by a porous tantalum system might achieve (1) better clinical outcome as reflected by the Knee Society Score (KSS) and WOMAC Osteoarthritis Index, (2) fewer complications and reoperations, and (3) improved radiographic results with respect to aseptic loosening compared with a conventional cemented implant.

METHODS

We randomized 145 patients into two groups, either a porous tantalum cementless tibial component group (Group 1) or cemented conventional tibial component in posterior cruciate retaining TKA group (Group 2). Patients were evaluated preoperatively and 15 days, 6 months, and 5 years after surgery, using the KSS and the WOMAC index. Complications, reoperations, and radiographic failures were tallied.

RESULTS

At 5-year followup the KSS mean was 90.4 (range, 68-100; 95% CI, ± 1.6) for Group 1, and 86.5 (range, 56-99; 95% CI, ± 2.4) for Group 2. The effect size, at 95% CI for the difference between means, was 3.88 ± 2.87. The WOMAC mean was 15.1 (range, 0-51; 95% CI, ± 2.6) for the Group 1, and 19.1 (range, 4-61; 95% CI, ± 2.9) for Group 2. The effect size for WOMAC was -4.0 ± 3.9. There were no differences in the frequency of complications or in aseptic loosening between the two groups.

CONCLUSIONS

Our data suggest there are small differences between the uncemented porous tantalum tibial component and the conventional cemented tibial component. It currently is undetermined whether the differences outweigh the cost of the implant and the results of their long-term performance.

Does bone marrow affect the radiological outcome when added to biphasic ceramic graft in treatment of benign bone lesions?

PURPOSE

The aim of this study is to describe the role of bone marrow aspirate in treatment of the benign bone lesions by comparing two groups of patients (16 patients in each group) with benign bone lesions treated with surgical curettage and filling the defect with either composite ceramic graft hydrated with bone marrow aspirate "group 1" or composite ceramic graft alone without a bone marrow aspirate "group 2".

MATERIALS AND METHODS

The mean age was 19.7 years (group 1) and 18.5 years (group 2). The mean size of the cavitary bone lesions was 29.2 cm(2) (group 1) and 25.9 cm(2) (group 2). The mean follow-up period was 47 months.

RESULTS

The percentage of ceraform resorption had increased from 31.3% at 6 months to 75.4% at 36 months for group 1 patients and from 20.9% at 6 months to 60.3% at 36 months for group 2 patients. The percentage of bone trabeculation through the cavitary defects had increased from 30.3% at 6 months to 85.5% at 36 months for group 1 patients and from 18.9% at 6 months to 72.0% at 36 months for group 2 patients. The mean of the percentage of ceraform persistence at 36 months after its implantation was 24.6% for group 1 patients and 39.7% for group 2 patients.

CONCLUSION

Adding bone marrow aspirate to ceraform biphasic ceramic had hastened the rate of its resorption and had decreased the rate of its persistence.

Obesity has a negative impact on clinical outcome after total knee arthroplasty

BACKGROUND AND AIMS

Obesity has been linked to the development of osteoarthritis of the knee and since the incidence of obesity is increasing, the need for total knee arthroplasty (TKA) is likely to increase. Conflicting findings have been reported concerning the relationship between obesity and TKA. It has been shown in several studies, that obese patients have poorer clinical results after operation. On the other hand it has also been reported similar results for obese and non-obese patients. The purpose of this study was to analyze clinically and radiologically the results of total knee artrhoplasty in obese patients.

MATERIAL AND METHODS

The study consisted of 48 patients who had a TKA. The patients were divided in two groups according their body mass index. Patients of BMI over 30 were regarded as obese.

RESULTS

The obese patients had poorer clinical success at the final follow-up, their WOMAC scores were significantly higher compared to non-obese (pain 20.7 vs. 11.6; p = 0.021, stiffness 26.9 vs. 13.4; p = 0.006, physical function 26.5 vs. 14.4; p = 0.003). Differences were also found in the Knee (KS) and Function (FS) scores and a long-term postoperative ROM and (KS: 83.6 vs. 88.9; p = 0.01, FS: 63.6/76.3; p = 0.051, ROM: 104.6 vs. 109.6; p = 0.016). Non-obese patients reached better percentage improvement in the KSS compared to obese patients (KS change + 194.5% vs. + 59.5%, p = 0.03; FS change + 51.5% vs. + 14.9%, p = 0.19).

CONCLUSIONS

Obesity has a negative impact on the outcome of TKA, assessed by patients' clinical function and satisfaction level.

Durability of a cruciate-retaining TKA with modular tibial trays at 20 years

BACKGROUND

Modular tibial trays have been utilized in TKA for more than 20 years. However, concerns have been raised about modular implants and it is unclear whether these devices are durable in the long term.

QUESTIONS/PURPOSES

We determined (1) survival, (2) relationship of age and polyethylene thickness with revision, (3) function, and (4) radiographic lucencies and osteolysis in patients having a single TKA implant at 20-year followup.

METHODS

We prospectively followed 75 patients implanted with 101 Press-Fit Condylar(®) (Johnson and Johnson Professional, Inc, Raynham, MA, USA) posterior cruciate-retaining TKAs (with modular tibial trays) between 1988 and 1991. At 20 years, 59 patients were deceased. We clinically evaluated the living 16 patients (22 knees) and contacted the relatives of all deceased patients to confirm implant status. We clinically assessed 14 of the 16 patients with the Knee Society score, WOMAC, and UCLA and Tegner activity level scores. Radiographically, we determined lucencies, component migration, and osteolysis. We performed survival analysis including all original patients. Minimum followup was 20 years (mean, 20.6 years; range, 20-21.8 years).

RESULTS

Six reoperations were performed in five patients (6% rate of revision) over the 20-year followup. All revisions were related to polyethylene wear and occurred at least 10 years after the primary procedure. Survivorship with revision for any reason as the end point was 91% (95% CI, 0.83-0.97) at 20 years. Average Knee Society clinical and functional scores were 90 (range, 60-100) and 59 (range, 30-87), respectively.

CONCLUSIONS

Our data demonstrate the durability of this posterior cruciate-retaining TKA design. The data provide a standard for newer designs and newer bearing surface materials at comparable followup.

Early migration of tibial components is associated with late revision: a systematic review and meta-analysis of 21,000 knee arthroplasties

PURPOSE

We performed two parallel systematic reviews and meta-analyses to determine the association between early migration of tibial components and late aseptic revision.

METHODS

One review comprised early migration data from radiostereometric analysis (RSA) studies, while the other focused on revision rates for aseptic loosening from long-term survival studies. Thresholds for acceptable and unacceptable migration were determined according to that of several national joint registries: < 5% revision at 10 years.

RESULTS

Following an elaborate literature search, 50 studies (involving 847 total knee prostheses (TKPs)) were included in the RSA review and 56 studies (20,599 TKPs) were included in the survival review. The results showed that for every mm increase in migration there was an 8% increase in revision rate, which remained after correction for age, sex, diagnosis, hospital type, continent, and study quality. Consequently, migration up to 0.5 mm was considered acceptable during the first postoperative year, while migration of 1.6 mm or more was unacceptable. TKPs with migration of between 0.5 and 1.6 mm were considered to be at risk of having revision rates higher than 5% at 10 years.

INTERPRETATION

There was a clinically relevant association between early migration of TKPs and late revision for loosening. The proposed migration thresholds can be implemented in a phased, evidence-based introduction of new types of knee prostheses, since they allow early detection of high-risk TKPs while exposing only a small number of patients.

Unicompartmental versus total knee arthroplasty database analysis: is there a winner?

BACKGROUND

TKA and unicompartmental knee arthroplasty (UKA) are both utilized to treat unicompartmental knee arthrosis. While some surgeons assume UKA provides better function than TKA, this assumption is based on greater final outcome scores rather than on change in scores and many patients with UKA have higher preoperative scores.

QUESTIONS/PURPOSES

We therefore asked whether TKA would demonstrate (1) better change in clinical outcome scores from preoperative to postoperative states and (2) better survivorship than UKA.

METHODS

We evaluated 4087 patients with 5606 TKAs and 179 patients with 279 UKAs performed between 1978 and 2009. Patients with TKA were older and heavier than patients with UKA (mean age, 68 versus 66 years; mean BMI, 32 versus 29). We compared preoperative, latest postoperative, and change in Knee Society Clinical Rating System (KSCRS), SF-12, and WOMAC scores. Minimum followup was 2 years (UKA: mean, 7 years; range, 2.0-23 years; TKA: mean, 6.5 years; range, 2.0-33 years). Preoperative outcome measure scores (WOMAC, SF-12, KSCRS) were higher in the UKA group.

RESULTS

Patients with UKA had higher postoperative KSCRS and SF-12 mental scores. Changes in score for all WOMAC domains were similar between groups. Total KSCRS changes in score were similar between groups, although patients with TKA had higher knee scores (49 versus 43) but lower function scores than UKA (21 versus 26). Cumulative revision rate was higher for UKA than for TKA (13% versus 7%). Kaplan-Meier survivorship at 5 and 10 years was 95% and 90%, respectively, for UKA and 98% and 95%, respectively, for TKA.

CONCLUSIONS

While patients with UKA had higher pre- and postoperative scores than patients with TKA, the changes in scores were similar in both groups and survival appeared higher in patients with TKA.

Gender differences in distal femoral morphology and the role of gender specific implants in total knee replacement: a prospective clinical study

Gender differences in distal femoral morphology may affect femoral component fit using a standard range of prostheses. The clinical relevance of this is controversial. Standardised measurements were taken from the distal femora of 50 males and 50 females during total knee replacement (TKR). Corresponding measurements were taken from the respective gender specific and standard femoral components. No demographic differences were noted. Significant differences in both frequency and magnitude existed in the medial-lateral femoral component overhang between the sexes. In females, standard implants overhung at the anterior flange width (AFW) by >2mm in 24/50 (48%) and by >3mm in 17/50 (34%) (p<0.001). Also at the anterior medial-lateral width (MLA) 29/50 (58%) overhung by >2mm and 24/50 (48%) by >3mm (p<0.001). In males, standard implants overhung by >2mm in 1/50 (2%). In females, gender specific implants overhung by >2mm in 3/50 (6%). Females had a mean aspect ratio of 1.02 (0.82 to 1.35) and men 0.98 (0.79 to 1.19). Femoral component overhang can occur in females undergoing TKR and a gender specific implant would reduce the potential for medial-lateral overhang. Long term studies are awaited to quantify the clinical implications of overhang.

The Rotaglide mobile bearing knee arthroplasty A 10- to 13-year review from an independent centre

The Rotaglide knee arthroplasty has a highly congruent mobile meniscal bearing allowing both rotation and antero-posterior translation. We reviewed 137 consecutive primary arthroplasties in 120 patients at mean 11.1 years (10-12.9) following surgery. No cases were lost to follow-up. Hospital for Special Surgery (HSS) and American Knee Society (AKSS) scores were recorded at a review clinic. Radiographs were assessed using the Knee Society's roentgenographic evaluation system. Forty-two patients had died, leaving 78 patients (87 knees) available for review. Sixty-four patients (70 knees) were assessed at a clinic and in 14 (17 knees) clinical outcomes were obtained via telephone and their most recent radiographs were assessed. There were three cases of aseptic loosening and one deep infection requiring revision surgery. Two meniscal bearings were replaced with thicker inserts, one following bearing fracture and one following bearing dislocation. Survival at 11 years for aseptic loosening was 97.6% (95% CI 94.3 to 1.0) and survival using re-operation for any cause was 95.3% (95% CI 90.8 to 99.8). The Rotaglide mobile-bearing total knee replacement demonstrates good survivorship and outcome scores at 11 years following surgery.

Pain relief and functional improvement remain 20 years after knee arthroplasty

BACKGROUND

TKA provides demonstrable pain relief and improved health-related quality of life. Yet, a decline in physical function may occur over the long term despite the absence of implant-related problems.

QUESTIONS/PURPOSES

(1) Does pain relief diminish over 20 years after TKA? (2) Does function decline over 20 years in terms of Knee Society function, knee, and walking scores? And (3) what is the patient-reported activity level at most recent followup?

PATIENTS AND METHODS

We retrospectively identified 1471 patients with 1757 primary cruciate-retaining TKAs implanted between 1975 and 1989 and identified 128 living patients (8.7%) with 171 TKAs. Ninety-three patients were women. We determined Knee Society scores prospectively and UCLA scores retrospectively. Minimum followup was 20 years (average, 21.1 years; range, 20-27 years). Average age at last followup was 82.3 years (range, 45-103 years). Of the 128 patients, 66 (73 TKAs) died after 20-year followup.

RESULTS

Pain scores did not diminish over time (average, 49; range, 20-50). Average knee score was 78 (range, 39-97). Function, stair, and walking scores diminished over time. Average function score was 70 (range, 5-100), primarily due to an average stair score of 35 (range, 0-50); average walking score was 37 (range, 10-50). All but two patients (two TKAs) could negotiate stairs; 95 patients (124 TKAs) could walk at least five blocks; three patients (three TKAs) were housebound. Of the 62 patients still living (98 TKAs), the average UCLA activity score was 8.3 (range, 5-10).

CONCLUSIONS

Although aging may cause a gradual decline in physical activity, an improved functional capacity and activity level continue 20 years or more after TKA.

The EUROP total knee prosthesis: a ten-year follow-up study of a posterior cruciate-retaining design

INTRODUCTION

The success of total knee arthroplasty is measured by pain relief, functional recovery, and implant survival duration. The aim of the present study was to evaluate the long-term clinical, functional and radiological results of the posterior cruciate ligament (PCL)-retaining fixed bearing EUROP implant.

HYPOTHESIS

The long-term results of EUROP implants are similar to those reported with comparable prostheses.

PATIENTS AND METHODS

We performed a prospective, monocentric study of a series of 121 cemented EUROP total knee arthroplasties, implanted between 1994 and 1996 in 117 patients mean age 73. A clinical and radiological evaluation was performed at 10 years of follow-up according to the International Knee Society (IKS) score. Twenty-three patients died, 14 were lost to follow-up, 43 underwent clinical and radiological evaluation and 37 were questioned by telephone.

RESULTS

The preoperative IKS knee score was 31 points (0-60) and increased to 88 points (30-98) at final follow-up, IKS function increased from 40 (0-90) to 80 points (25-100). Radiolucencies were observed in 56% of the condyles and 60% of tibial plates. Ninety-three percent of these radiolucent lines were less than 1mm wide. Three patients underwent revision TKA at 32 months, eight and 11 years respectively. Global implant survival was 99% at five years, 97.8% at 10 years and 95.8% at 12 years.

DISCUSSION

The clinical and radiological results of the cruciate-retaining fixed bearing EUROP total knee arthroplasties, with three cases of revision arthroplasty at 12 years of follow-up are satisfactory and comparable to similar implants.

Assessing the character of the rhBMP-2- and vancomycin-loaded calcium sulphate composites in vitro and in vivo

BACKGROUND

The treatment of contaminated and infected bone defects remains an intractable problem and the ideal approach is to control infection and repair the bone defect at the same time. Thus, developing an osteoconductive bone graft composite with antibiotic and growth factor release capabilities as well as osteogenesis-matched degradation properties is necessary. A new calcium sulphate composite consisting of vancomycin and rhBMP-2 was developed, and the present study assessed its efficiency in vitro and in a rabbit tibial defect model.

METHODS

Firstly, we detected the bioactivity of rhBMP-2 released from the composites by ALP assay in vitro. Then, the released vancomycin in bone tissue within 1 cm from implanted site was detected by HLPC at 1, 3, 5, 7, 14, 21 and 28 days after implantation. The rhBMP-2 concentration of tissues around the defects was also detected by ELISA. Histomorphometry and histomorphometrical analysis at 5, 14 and 28 days post-implantation was done for assessing its osteoinductivity for bone defects.

RESULTS

The results showed rhBMP-2 was still active in vitro at 29 days. In vivo, the composite released an initial bolus of vancomycin and rhBMP-2 to the bone followed by gradual release for more than 14 and 21 days, respectively. The histomorphometry indicated that the composite significantly augmented new bone formation in the defect compared to the control.

CONCLUSIONS

This composite may be a potential therapeutic agent for contaminated or infected bone defects due to its concomitant osteoinductive and antibiotic properties.

Cemented versus uncemented femoral components in total knee arthroplasty

PURPOSE

The aim of this study is to analyse the influence of femoral cement on clinical and radiological results after total knee arthroplasty.

METHODS

Preoperatively 130 patients were randomly assigned to treatment in either the Cement Group or the Hybrid Group. The International Knee Society scores, femoral radiolucent lines and bone transparencies were compared.

RESULTS

There were no significant differences concerning postoperative knee and function scores. We observed a significant difference in radiolucent lines (Cement Group, 24%; Hybrid Group, 2%; P < 0.001) as well as bone transparencies (Cement Group, 21%; Hybrid Group, 62%; P < 0.001). All radiolucent lines measured less than 2 mm in width.

CONCLUSION

Cementing the femoral component of a total knee arthroplasty does not appear to influence the clinical results. A longer follow-up period is required to determine the influence of radiological findings on final outcome.

Transpedicular grafting after short-segment pedicle instrumentation for thoracolumbar burst fracture: calcium sulfate cement versus autogenous iliac bone graft

STUDY DESIGN

A retrospective clinical and radiographic study was performed.

OBJECTIVE

To compare 2 grafting materials of anterior augmentation for thoracolumbar burst fractures: transpedicular cancellous bone (TPCB) grafting and transpedicular calcium sulfate grafting and to decide whether calcium sulfate cement can replace autogenous cancellous bone applied in anterior vertebral body augmentation after posterior short-segment instrumentation.

SUMMARY OF BACKGROUND DATA

Additional TPCB grafting was developed as an alternative to prevent early implant failure. However, the results are inconsistent and donor-site complications are a major concern. Calcium sulfate has been offered as a bone substitute for treating patients with metaphysis fractures or bone defect, but the results of application in spinal surgeries are uncertain.

METHODS

Fifty-one patients with a single-level thoracolumbar burst fracture for treatment with short-segment pedicle screw fixation were enrolled in the study. Fractures in group 1 patients were reinforced with TPCB (n = 31), and fractures in group 2 patients were augmented with transpedicular calcium sulfate cement (TPCSC; n = 20). All patients were followed-up at least 2 years after surgery. Radiographic parameters and clinical outcomes were compared between the 2 groups.

RESULTS

The 2 groups were similar in age, sex, fracture levels, preoperative neurologic status distribution, and the associated injuries. The TPCB group had a longer period of follow-up (52.7 +/- 4.9 vs. 28.6 +/- 3.5 months, P < 0.001). Blood loss and operation time were less in the TPCSC group (247.5 +/- 164.2 vs. 600.0 +/- 403.1 mL, P = 0.001 and 161.7 +/- 28.5 vs. 227.2 +/- 43.6 minutes, P < 0.001). Radiographic parameters and clinical outcomes were similar in both groups. The TPCSC group had no surgical complication, but the TPCB group revealed 2 cases with wound infection after surgery. The failure rate, defined as an increase of 10 degrees or more in loss of correction or implant failure, was also not significantly different (TPCB = 9.6% and TPCSC = 15%; P = 0.565). All patients with partial neurologic deficits initially improved at the final follow-up.

CONCLUSION

Additional TPCB grafting after posterior short-segment instrumentation remains a reliable surgical method for correcting and maintaining sagittal alignment and vertebral body height in thoracolumbar burst fractures. Calcium sulfate cement also proved to be an effective bone substitute used in spinal surgeries for patients with thoracolumbar burst fractures.

Surgeon's expectations do not predict the outcome of a total knee arthroplasty

INTRODUCTION

It is fascinating for both the patient and the surgeon to predict the outcome of a TKA at an early stage. Satisfaction after TKA is primarily determined by the preoperative expectations of the patient. The purpose of this study was to investigate if the peri-operative expectations of the surgeon predicted the outcome of a TKA.

PATIENTS AND METHODS

A prospective study of 53 primary TKAs was performed. Preoperatively, the surgeon described the assessment of the difficulty of the TKA on a VAS. Immediately postoperative, the surgeon gave his satisfaction VAS about the procedure. After 1 year the surgeon's satisfaction VAS, the patient's satisfaction VAS and the KSCRS were determined.

RESULTS

The Spearman's correlation coefficients between the preoperative difficulty assessment, the immediate postoperative satisfaction and the outcome measurements after 1 year were all very poor (-0.01 to 0.23).

CONCLUSIONS

The outcome of a TKA depends on multiple factors. Both the surgeon's preoperative assessment of the difficulty and the surgeon's immediate postoperative satisfaction do not independently predict the outcome of a TKA.

Minimally invasive computer-navigated total knee arthroplasty

Modern computerized knee navigation systems aid surgeons both in the conventional and in the minimally invasive approach to optimize mechanical and rotational alignments of the components in all three planes to avoid any malrotation and/or any errors in coronal, sagittal, and axial alignments. The advantages of minimally invasive total knee arthroplasty can be achieved without loss of accuracy. There is increasing evidence of a positive correlation between accurate mechanical alignment after total knee arthroplasty and functional as well as quality-of-life patient outcomes.

Cemented versus uncemented fixation of the femoral component of the NexGen CR total knee replacement in patients younger than 60 years: a prospective randomised controlled RSA study

The optimal mode of femoral fixation in total knee arthroplasty (TKA) remains controversial, especially for the young patient. In a prospective randomised study we compared the magnitude and pattern of the fixation of cemented versus uncemented femoral components during 2 years in patients younger than 60 years. Forty-one knees in 41 patients were randomised to receive a NexGen (Zimmer, Warsaw, USA) cruciate-retaining TKA with either a cemented or an uncemented non HA-coated femoral component. The patients were examined by radiostereometric analysis (RSA), as well as clinical and radiological evaluation. The magnitude and pattern of migration as measured by RSA did not differ significantly between the cemented and uncemented fixation during the 2-year follow-up, nor were there any differences between the groups in clinical parameters. These findings suggest that an uncemented and non HA-coated femoral component may behave equally as well as a cemented one in the long-term.

Mechanical accuracy of navigated minimally invasive total knee arthroplasty (MIS TKA)

This study was designed to provide evidence that computer-navigated minimally invasive total knee arthroplasty (MIS CN-TKA) enables identical mechanical accuracy as conventional computer navigated total knee arthroplasty (CN-TKA) while reducing rehabilitation time and hospital stay of the patients. Two groups of 20 patients requiring total knee arthroplasty due to degenerative or posttraumatic knee osteoarthritis were included. Twenty consecutive patients received conventional CN-TKA and 20 consecutive patients received minimally invasive CN-TKA. Mechanical and rotational alignments were measured preoperatively and 6 months postoperatively on long-standing radiographs, on conventional coronal and sagittal views and on CT-scans of the knee. Length of skin incision, operating time, blood loss, length of hospital stay, postoperative ROM and HSS as well as KSS scores were determined. Postoperative mechanical axis improved significantly in both groups. Coronal and sagittal component positioning were accurate in both groups without significant differences. Rotational alignment showed the desired reproducible values without significant differences between the two groups. The posterior slope of the tibial component was significantly reconstructed to match the preoperative condition in both groups. The coronal alignment of the femoral and tibial components showed accurate reproducible results for implantation of both components in both groups. Length of skin incision was significantly shorter in the MIS CN-TKA. Duration of hospital stay was significantly reduced in the MIS CN-TKA group. Operating time and blood loss were similar in both groups. Postoperative ROM after the first 3 months was significantly higher in MIS CN-TKA, but after 6 months differences were minimal. Clinical outcome scores were identical for both groups 6 months after surgery. The advantages of CN-TKA are well known. Performing computer navigated TKA in combination with a minimally invasive approach in this study lead to a reduction of hospital stay and an initially increased ROM without differences in operating time and blood loss. Computer navigation in TKA preserves accurate coronal, sagittal and rotational components alignment even with a minimally invasive approach.

The female knee: anatomic variations and the female-specific total knee design

The concept and need for a gender-specific or female-specific total knee prosthesis have generated interest and discussion in the orthopaedic community and the general public. This concept relies on the assumption of a need for such a design and the opinion that there are major anatomic differences between male and female knees. Most of the information regarding this subject has been disseminated through print and Internet advertisements, and through direct-to-patient television and magazine promotions. These sources and a recent article in a peer-reviewed journal, which support the need for a female-specific implant design, have proposed three gender-based anatomic differences: (1) an increased Q angle, (2) less prominence of the anterior medial and anterior lateral femoral condyles, and (3) reduced medial-lateral to anterior-posterior femoral condylar aspect ratio. We examined the peer-reviewed literature to determine whether women have had worse results than men after traditional TKAs. We found women have equal or better results than men. In addition, we reviewed the evidence presented to support these three anatomic differences. We conclude the first two proposed differences do not exist, and the third is so small that it likely has no clinical effect.

LEVEL OF EVIDENCE

Level IV, systematic review. See the Guidelines for Authors for a complete description of levels of evidence.

Survivorship analysis at 15 years of cemented press-fit condylar total knee arthroplasty

We performed a survival analysis on 354 cemented primary press-fit condylar total knee arthroplasties in 277 patients with prospective follow-up (mean, 8.8 years; range, 0.3-16.9 years). The number of patients alive reaching 15 years at follow-up for survival analysis was 15. The cumulative survival rate at 15 years was 81.7% (95% confidence interval, 72.1%-88.5%), using revision for all causes as our end point. Indications for revision in our patient group were aseptic loosening 4.5%, infection 2.3%, and exchange of polyethylene insert 1.1%. Our results indicate that the cemented press-fit condylar total knee arthroplasty has a good long-term survival, at 15 years, based on revision as the end point.

[Total knee arthroplasty - GPs' views in Germany: a questionnaire-based study]

To assess general knowledge and individual views of general practitioners (GPs) on total knee arthroplasty (TKA), we conducted a questionnaire-based survey involving 170 GPs in Germany. Eighty-one GPs returned the questionnaire. They treat a mean of 10.6+/-8.3 patients with TKA. General knowledge can be estimated as good. Compared with the data in the literature, GPs assessed the rate of satisfied patients as lower and the risk for revision surgery as higher. The mean risk of potential complications (infection, instability, persistent pain) in association with TKA was estimated correctly. Seventy-eight percent of GPs consider an allergic reaction to the implant or bone cement as problematic. The number of cases per year, personal experience with the surgeon, and - less important - local accessibility are important factors for GPs when recommending an operating centre to a patient.A broad spectrum of individual responses indicates the need to improve the information transfer between orthopaedic surgeons and referring GPs.

Outcome following knee arthroplasty beyond 15 years

There is a paucity of information detailing functional outcome following total knee arthroplasty for this length of follow-up. We collected data from 187 knees in 150 surviving patients, beyond 15 years from implantation. Survival of the implant was confirmed and a patient administered questionnaire including WOMAC, SF-36 and patient satisfaction was used, data was scrutinised for differences between primary and revision knee surgery. Seventy knees were revised at a mean of 10.8 years. The mean WOMAC Pain score was 72 indicating predominantly mild pain. The mean WOMAC Function scores were lower at 55 indicating moderate limitation of most activities. No significant differences were found between revised and un-revised patients. Long-term pain and satisfaction scores in this population were good illustrating the benefits of TKA in the long term even in patients who have undergone revision surgery.

Internet promotion of minimally invasive surgery and computer-assisted orthopedic surgery in total knee arthroplasty by members of American Association Of Hip And Knee Surgeons

Minimally invasive surgery (MIS) and computer-assisted orthopedic surgery (CAOS) surgical options in total knee arthroplasty (TKA) have recently prompted increased discussion. This study addresses the question, "What is the level of promotion of MIS and CAOS TKAs through the Internet by American Association of Hip and Knee Surgeons (AAHKS) members?" Google, Yahoo, and Excite were used to search for Web sites related to active members of the AAHKS. Web sites were evaluated for MIS and CAOS TKAs information. Direct (surgeon/private practice) and indirect (institution/hospital) information from each site was evaluated. Seven hundred eighteen active AAHKS members were found to have 727 total Web sites. These sites (8.4% and 12.7%) made indirect and direct reference to MIS TKA, respectively (P < .01). In contrast, MIS-specific TKA risks were presented by only 55.7% and 25% of the sites, respectively (P < .001). Computer-assisted orthopedic surgery TKA was discussed in 4.3% and 5.6% of these sites, respectively (P < 1.0). Although our findings confirm that MIS and CAOS TKAs are not commonly promoted via the Internet by members of the AAHKS, MIS and CAOS TKAs can potentially be associated with these surgeons via institutional Web sites or hospital affiliations (12.7% direct claims with an additional 8.4% indirect claims).

A new articulated distraction arthroplasty device for treatment of the osteoarthritic knee joint: a preliminary report

PURPOSE

The aim of this study was to evaluate the clinical results of a new distraction arthroplasty device when used in conjunction with a bone marrow-stimulating technique for the treatment of osteoarthritis of the knee.

METHODS

We developed a new distraction arthroplasty device that allows continuous joint movement. We compared preoperative and postoperative findings for 6 knees (6 patients; age range, 42 to 58 years). The fixation period for the distraction device ranged from 7 to 13 weeks, and the follow-up period ranged from 1 to 3.5 years.

RESULTS

The Japanese Orthopaedic Association knee score, range of motion, and joint space values were significantly improved in all cases at the latest follow-up (P < .05). Scores on a visual analog pain scale were also significantly improved (P < .05).

CONCLUSIONS

We conclude that treatment using this new arthroplasty device in combination with a bone marrow-stimulating method was effective for osteoarthritic knees in middle-aged patients.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Internet promotion of MIS and CAOS in TKA By Knee Society members

Minimally invasive surgery (MIS) and computer-assisted orthopaedic surgery (CAOS) options for total knee arthroplasty (TKA) have become increasingly popular. However, few controlled studies document their efficacy and safety. We examined the Internet for Knee Society members' websites to evaluate the level of promotion for these procedures in terms of direct (surgeon endorsed) and indirect (surgeon associated) information. On 92 websites, 22.7% made indirect reference to MIS TKA, while only 10.9% made a direct reference. Of the sites referencing MIS TKA, faster recovery was reported on 90% of indirect sites and 50% of direct sites. Specific risks were discussed on only 35% of indirect sites, and on only 20% of direct sites. CAOS TKA was discussed on 6.5% of indirect sites and on 5.4% of direct sites. Although MIS and CAOS TKA are frequently discussed on the Internet, only a small percentage of KS members directly promote these techniques (10.9% and 5.4%, respectively). Information was often indirectly associated with KS surgeons through institutional websites or hospital affiliations. Information indirectly associated with a surgeon may be mistaken as endorsing the procedure by a prospective patient.

The Chitranjan Ranawat Award: Long-term survivorship and failure modes of 1000 cemented condylar total knee arthroplasties

We examined factors affecting survivorship, and reasons for reoperation and revision of a cemented modular condylar total knee arthroplasty (TKA). One thousand and eight consecutive primary cemented cruciate-retaining TKAs performed at one institution were studied. At the time of review, 411 patients (562 knees) had died, 43 patients (45 knees) had their knee components revised or removed, and 47 patients (62 knees) were lost to followup. Mean followup of living patients with their TKA components in situ (244 patients, 331 knees) was 15.7 years. Survivorship at 15 years for revision for any reason, revision for mechanical failure, and revision for aseptic loosening were 95.9%, 97.0%, and 98.8% respectively. Survivorship was poorer among patients aged less than 60. Forty-five knees had components removed or revised; approximately one-third were removed for infection, one-third for aseptic loosening or tibial polyethylene wear, and one-third for other causes. Mechanical implant failures accounted for less than one-half of the reoperations and revisions, while infection and periprosthetic fractures accounted for a substantial portion of revisions and reoperations. Because mechanical arthroplasty failures have become less common, other complications related to arthroplasty have become proportionately more frequent.

Management of segmental bony defects: the role of osteoconductive orthobiologics

Our knowledge about, and the availability of, orthobiologic materials has increased exponentially in the last decade. Although previously confined to the experimental or animal-model realm, several orthobiologics have been shown to be useful in a variety of clinical situations. As surgical techniques in vascular anastomosis, soft-tissue coverage, limb salvage, and fracture stabilization have improved, the size and frequency of bony defects (commensurate with the severity of the initial injury) have increased, as well. Because all methods of managing segmental bony defects have drawbacks, a need remains for a readily available, void-filling, inexpensive bone substitute. Such a bone substitute fulfills a permissive role in allowing new bone to grow into a given defect. Such potential osteoconductive materials include ceramics, calcium sulfate or calcium phosphate compounds, hydroxyapatite, deproteinized bone, corals, and recently developed polymers. Some materials that have osteoinductive properties, such as demineralized bone matrix, also display prominent osteoconductive properties.

Unicompartmental or total knee arthroplasty?: Results from a matched study

There are few direct comparative studies evaluating results after unicompartmental knee arthroplasty and total knee arthroplasty. We determined the active range of motion, Knee Society score, and 5-year survivorship rate after 54 consecutive unilateral unicompartmental knee arthroplasties compared with a matched group of 54 unilateral total knee arthroplasties. The two groups of patients were matched for age, gender, body mass index, preoperative active range of movement, and preoperative Knee Society scores. All patients had osteoarthritis of the knee. Patients were assessed prospectively at 6, 18, 36, and 60 months postoperatively, and the mean followup was 59 months in both groups. The mean postoperative active range of motion was greater after unicompartmental knee arthroplasty, but there were no differences in the overall Knee Society knee and function scores. The 5-year survivorship rate based on revision for any reason was 88% for unicompartmental knee arthroplasty and 100% for total knee arthroplasty. The worst case 5-year survivorship rate, assuming all patients lost to followup had revision surgery, was 85% for unicompartmental knee arthroplasty and 98% for total knee arthroplasty. Total knee arthroplasty was a more reliable procedure. Midterm clinical outcomes were similar for both procedures, but the complication rate may be greater for unicompartmental knee arthroplasty.

Oberflächenkonditionierung für eine verbesserte Überlebenswahrscheinlichkeit von Knieprothesen: Komplett- vs. Oberflächenzementiertechnik der Tibiakomponente / Surface pretreatment for prolonged survival of cemented tibial prosthesis components: full- vs. surface-cementation technique

Aseptic loosening of tibial components due to degradation of the interface between bone cement and metallic tibial shaft component is still a persistent problem, particularly for surface-cemented tibial components. The surface cementation technique has important clinical meaning in case of revision and for avoidance of stress shielding. This study was done to prove crack formation in the bone cement near the metallic surface when this is not coated. We propose a newly developed coating process by SiOx-PVD layering to avoid crack formation. A biomechanical model for a vibration fatigue test was done to prove that crack formation can be significantly reduced in the case of coated surfaces. It was found that coated tibial components showed a highly significant reduction of cement cracking near the metal/bone cement interface (p < 0.01) and a significant reduction of gap formation in the metal-to-bone cement interface (p < 0.05). Coating dramatically reduces hydrolytic- and stress-related crack formation at the prosthesis metal/bone cement interface. This leads to a more homogenous load transfer into the cement mantle which should reduce the frequency of loosening in the metal/bone cement/bone interfaces. With surface coating of the tibial component it should become possible that surface-cemented TKAs reveal similar loosening rates as TKAs both surface- and stem-cemented. This would be an important clinical advantage since it is believed that surface cementing reduces metaphyseal bone loss in the case of revision and stress shielding for a better bone health.

Bone graft substitutes

The current gold standard of bone grafts is the autograft since it possesses all the characteristics necessary for new bone growth, namely osteoconductivity, osteogenicity and osteoinductivity. However, the autograft has its limitations, including donor-site morbidity and supply limitations, hindering this as an option for bone repair. An extensive list of currently available alternatives to bone grafts is provided, along with a classification scheme that divides these bone graft substitutes into five groups depending on the primary material composition: allograft, cell, factor, ceramic and polymer. Of the bone graft substitutes listed, several are discussed in detail. Beyond the current state of the art, attention is paid to what lies ahead in the field of bone graft substitutes. Biodegradable composite structures and various new architectures are discussed, as are newly developed polymeric materials, with tissue engineering providing the platform for future directions within this discipline.

Survivorship analysis of 3234 primary knee arthroplasties implanted over a 26-year period: a study of eight different implant designs

We conducted a survivorship analysis of 3234 primary total knee replacements performed at our hospital between 1969 and 1995. Each knee replacement was entered once only. Revision was defined as the end point. Data were collected both from patient records and by postal questionnaire. Eight types of knee prostheses were evaluated with best-case and worst-case scenarios compared over a 5-, 10- and 15-year period. The evidence suggests that the "Condylar type devices" which include the Total Condylar, Press Fit Condylar (PFC), Kinematic, Kinemax and Anatomic Modular Knee (AMK) have very similar survivorship curves and in the main have performed well up to a 10-year period. The LCS mobile bearing knee performed well at 5 years. The earlier design prostheses had a poor result in terms of survivorship and are hence were discontinued.

Surface pretreatment for prolonged survival of cemented tibial prosthesis components: full- vs. surface-cementation technique

Background

One of few persisting problems of cemented total knee arthroplasty (TKA) is aseptic loosening of tibial component due to degradation of the interface between bone cement and metallic tibial shaft component, particularly for surface cemented tibial components. Surface cementation technique has important clinical meaning in case of revision and for avoidance of stress shielding. Degradation of the interface between bone cement and bone may be a secondary effect due to excessive crack formation in bone cement starting at the opposite metallic surface.

Methods

This study was done to prove crack formation in the bone cement near the metallic surface when this is not coated. We propose a newly developed coating process by PVD layering with SiO_x to avoid that crack formation in the bone cement. A biomechanical model for vibration fatigue test was done to simulate the physiological and biomechanical conditions of the human knee joint and to prove excessive crack formation.

Results

It was found that coated tibial components showed a highly significant reduction of cement cracking near the interface metal/bone cement (p < 0.01) and a significant reduction of gap formation in the interface metal-to-bone cement (p < 0.05).

Conclusion

Coating dramatically reduces hydrolytic- and stress-related crack formation at the prosthesis interface metal/bone cement. This leads to a more homogenous load transfer into the cement mantle which should reduce the frequency of loosening in the interfaces metal/bone cement/bone. With surface coating of the tibial component it should become possible that surface cemented TKAs reveal similar loosening rates as TKAs both surface and stem cemented. This would be an important clinical advantage since it is believed that surface cementing reduces metaphyseal bone loss in case of revision and stress shielding for better bone health.

15-year follow-up study of total knee arthroplasty in patients with rheumatoid arthritis

In 25 patients with rheumatoid arthritis, 36 cases of cemented Kinematic total knee arthroplasty were reviewed clinically and radiographically at 13 to 19 years after surgery. The mean age at the time of surgery was 51.6 +/- 8.9 years. According to the follow-up results evaluated with the Hospital for Special Surgery knee scoring system, 28 knees (77.7%) were classified as good or excellent. The mean flexion angle at follow-up evaluation was 99 degrees +/- 24 degrees (10 degrees -140 degrees ). At the tibial or femoral bone-cement interfaces, a radiolucent line was seen in 10 of 36 knees (27.8%) at follow-up evaluation. The survival rate of prostheses with revision as the endpoint was estimated to be 93.7% at 15 years. Kinematic total knee arthroplasty in rheumatoid arthritis patients provided a good long-term outcome.