Total knee arthroplasty using cruciate-retaining kinematic condylar prosthesis

Effects of an Early Exercise Program with Cryotherapy on Range of Motion, Pain, Swelling, and Gait in Patients with Total Knee Arthroplasty: A Randomized Controlled Trial

Background: This study aimed to investigate the effects of cryotherapy on range of motion, pain, swelling, and gait in patients who underwent total knee arthroplasty. Methods: Forty-three patients who underwent TKA (total knee arthroplasty) and met the inclusion criteria were randomly divided into two groups. The experimental (n = 21) and control (n = 22) groups underwent cryotherapy and non-cryotherapy treatments, respectively, six times a week for two weeks, and once each before and after exercise for 3 min. Both groups followed a similar initial rehabilitation exercise program using a continuous passive motion device. Results: The results showed a significant difference in knee flexion range of motion, pain, edema, and 10 MWT comparisons from pre- to post-test (p < 0.001). The above values were also significantly different in the comparison between the two groups (p < 0.05). Conclusions: Therefore, this study confirmed that an initial rehabilitation exercise program accompanied by cryotherapy could be an effective intervention method for range of motion, pain, edema, and walking in patients undergoing total knee arthroplasty.

Trends in Periprosthetic Knee Infection and Associated Costs: A Population-Based Study Using National Data

Given increasing demand for primary knee arthroplasties, revision surgery is also expected to increase, with periprosthetic joint infection (PJI) a main driver of costs. Recent data on national trends is lacking. We aimed to assess trends in PJI in total knee arthroplasty revisions and hospitalization costs. From the National Inpatient Sample (2003-2016), we extracted data on total knee arthroplasty revisions (n = 782,449). We assessed trends in PJI prevalence and (inflation-adjusted) hospitalization costs (total as well as per-day costs) for all revisions and stratified by hospital teaching status (rural/urban by teaching status), hospital bed size (≤299, 300-499, and ≥500 beds), and hospital region (Northeast, Midwest, South, and West). The Cochran-Armitage trend test (PJI prevalence) and linear regression determined significance of trends. PJI prevalence overall was 25.5% (n = 199,818) with a minor increasing trend: 25.3% (n = 7,828) in 2003 to 28.9% (n = 19,275) in 2016; p < 0.0001. Median total hospitalization costs for PJI decreased slightly ($23,247 in 2003-$20,273 in 2016; p < 0.0001) while median per-day costs slightly increased ($3,452 in 2003-$3,727 in 2016; p < 0.0001), likely as a function of decreasing length of stay. With small differences between hospitals, the lowest and highest PJI prevalences were seen in small (≤299 beds; 22.9%) and urban teaching hospitals (27.3%), respectively. In stratification analyses, an increasing trend in PJI prevalence was particularly seen in larger (≥500 beds) hospitals (24.4% in 2003-30.7% in 2016; p < 0.0001), while a decreasing trend was seen in small-sized hospitals. Overall, PJI in knee arthroplasty revisions appears to be slightly increasing. Moreover, increasing trends in large hospitals and decreasing trends in small-sized hospitals suggest a shift in patients from small to large volume hospitals. Decreasing trends in total costs, alongside increasing trends in per-day costs, suggest a strong impact of length of stay trends and a more efficient approach to PJI over the years (in terms of shorter length of stay).

[Postoperative mobilization after total hip arthroplasty : Measured by Fitbit activity trackers]

BACKGROUND

Patients are becoming increasingly more independent and self-determined, in addition to having shorter post-operative hospitalization. This is why it is more important than ever to actively involve patients in the follow-up treatment. The question arises as to whether post-operative rehabilitation can be improved with modern devices.

METHODS

As part of a prospective study, the post-operative mobilization was recorded and analyzed by Fitbit®-activity-trackers between 05/2016 and 08/2017 in 100 patients who received a THA. 50 men (Ø 70.6y) and 50 women (Ø 71.1y) were included. Furthermore, the patients were interviewed about their acceptance of the Fitbit®-wristband.

RESULTS

The average hospital stay was 7.98 days (SD ± 1.76). The number of steps on the first post-operative day was 712 (SD ± 617). On average (during total hospitalization), 1528 (SD ± 1076) steps were completed daily. One day before discharge, the average number of steps was 2165 (SD ± 1570) on that particular day. There were no gender differences in age and pre-operative Harris hip scores (♂55.3 vs. ♀53.9). Also, there were no statistically significant differences in the number of steps on the first postoperative day (♂745 vs. ♀678). A statistically significant result can be found in the number of steps prior to discharge: on this day, the men took 2483 and the women 1846 steps (p = 0.04). 42% of our patients own a modern smartphone and are able to operate software applications. 52% of the patients found the activity tracker to be motivating, 65% were open to new technologies (e.g. activity trackers) in the hospital. 14% did not check at all or only queried their wristband data once a day, 65% queried 2-4 times/day, and 21% retrieved the data >5 times/day.

DISCUSSION

On average, 1528 steps were completed daily. In a comparison of the men and women, the men were only able to demonstrate significantly more steps than the women on the day prior to discharge. The men had significantly shorter hospital stays than the women. The younger the patients, the more mobile they were. A majority of patients are familiar with and/or interested in new technologies. This interest and curiosity should be consciously used for integration in the post-operative treatment.

The monitoring of activity at home after total hip arthroplasty

AIMS

Total hip arthroplasty (THA) has well known subjective benefits, but little is known objectively about the recovery of mobility in the early post-operative period.

PATIENTS AND METHODS

A total of 33 patients aged > 60 years who underwent elective primary THA had their activity monitored for 30 days post-operatively using an at-home (Fitbit) ankle accelerometer. Their mean age was 70.7 years (61 to 86); 15 (45.5%) were female. The rate of compliance and the mean level of activity were determined. Comparisons between subgroups based on age, body mass index (BMI), surgical approach, and the destination of the patients when discharged were also performed.

RESULTS

The mean compliance over the 30 days was 26.7 days (16 to 30; 89%) of use. The mean number of steps increased from 235 (5 to 1152) to 2563 (87 to 7280) (p < 0.001) between the first and the 30th post-operative day. Age < 70 years and an anterior surgical approach were significantly associated with higher levels of activity (1600 to 2400 (p = 0.016 to 0.031) and 1000 to 1800 (p = 0.017 to 0.037) more steps per day, respectively) between the second and the fourth week post-operatively. There was also a trend towards higher levels of activity in those who were discharged to their home rather than to a nursing facility (a mean of 1500 more steps per day, p = 0.02). BMI greater or less than 30 kg/m² was not predictive of activity (p = 0.45 to 0.98).

CONCLUSION

At-home remote mobility monitoring using existing commercially available technology is feasible in patients who have undergone THA. It showed a clear trend towards increased activity with the passage of time. Additionally, the remote device was able to detect differences in levels of activity clearly between patients in relation to variables of interest including age, BMI, surgical approach, and the destination of the patient at the time of discharge from hospital. Such monitoring may allow for the early identification and targeted intervention in patients who recover slowly. Cite this article: Bone Joint J 2016;98-B:1450-4.

Primary total knee arthroplasty for elderly complex tibial plateau fractures

Objective

The aim of this study is to evaluate the clinical and radiologic results of primary Total Knee Arthroplasty (TKA) for elderly complex tibial plateau fractures.

Materials and methods

Between November 2010 and February 2012, six cases of elderly complex tibial plateau fractures were treated with primary TKA using the standard medial parapatellar approach. All six patients were available at follow up with mean duration of 32.3 months (range 25–41 months). There were 3 women and 3 men with an average age of 69.5 years (58–78 years) at the time of the arthroplasty.

Results

The mean Hospital for Special Surgery (HSS) knee score was 89.8 (range 85–94): 6/6 excellent. The mean knee flexion was 119.2° (105–130°). No significant postoperative complications were noted. None of these patients had significant postoperative knee pain required revision surgery, or had radiographic loosening of the components at the latest follow-up.

Conclusions

TKA is a suitable solution for the treatment of elderly patients with complex tibial plateau fractures.

Level of Evidence

Level IV, Therapeutic study

Prevalence of knee arthroplasty in the state of São Paulo between 2003 and 2010

CONTEXT AND OBJECTIVE:

The volume of knee arthroplasty procedures has increased over the last decade. The aim of this study was to estimate the frequency of these procedures performed within the public healthcare system of the state of São Paulo between 2003 and 2010.

DESIGN AND SETTING:

Cross-sectional study conducted in the state of São Paulo by researchers at Hospital do Servidor Público do Estado de São Paulo.

METHODS:

A sample of 10,952 patients (7,891 females and 3,061 males) who underwent primary total knee arthroplasty (TKA) and revision of total knee arthroplasty (RTKA) in the state of São Paulo between 2003 and 2010 was evaluated. The patients were cataloged using the public healthcare service's TABNET software. All of the patients presented primary osteoarthritis of the knee. The variables of gender, number of primary TKA procedures and number of RTKA procedures were evaluated.

RESULTS:

A total of 10,952 TKA procedures were performed (annual average of 1369), of which 9,271 (85%) were TKA and 1,681 (15%), RTKA. Of the TKA procedures, 72% were carried out on females (P < 0.0001), while 70% of the RTKA procedures were on females (P < 0.0001). The average ratio of TKA to RTKA was 5.5:1 (P < 0.0001); the ratios in 2003 and 2010 were 9.0:1 and 4.4:1 (P < 0.0001), respectively.

CONCLUSION:

The number and frequency of TKA and RTKA procedures increased in the state of São Paulo between 2003 and 2010. This increase was relatively greater in RTKA than in TKA and was predominantly in female patients.

Predominance of synovial sensory nerve fibers in arthrofibrosis following total knee arthroplasty compared to osteoarthritis of the knee

BACKGROUND

So far, there exists no golden standard for the treatment of arthrofibrosis (AF) following total knee arthroplasty (TKA). Although pain is a hallmark of AF, nociceptive nerve fibers have never been investigated in affected joint tissue.

METHODS

A total of 24 patients with osteoarthritis (OA) of the knee (n = 12) and post-TKA AF of the knee (n = 12) were included. Along evaluation of typical clinical signs and symptoms by using the Knee Society Clinical Rating System (KSS), the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC index), the innervation of joint tissue was studied by semiquantitative immunofluorescence of nerve fibers.

RESULTS

Patients with AF compared to OA had a lower KSS and lower KOOS. In all compartments (anterior, medial, and lateral recesses), the density of synovial sympathetic nerve fibers was significantly higher in OA compared to AF, which was also true for the density of sensory nerve fibers in the medial and lateral recesses. In synovial tissue of the anterior recess of patients with AF compared to OA, the density of nociceptive sensory nerve fibers was significantly higher relative to sympathetic nerve fibers. This was similarly observed in the neighboring infrapatellar fat pad of the knee.

CONCLUSIONS

Similar as in many painful musculoskeletal diseases, this study indicates that patients with arthrofibrosis of the knee after TKA demonstrate a preponderance of profibrotic sensory nerve fibers over antifibrotic sympathetic nerve fibers. This could serve as a starting point for AF therapy with specific antifibrotic pain medication or regional anesthetic techniques.

Periprosthetic Fractures: A Common Problem with a Disproportionately High Impact on Healthcare Resources

The present study evaluated the frequency of periprosthetic fractures and tested the hypothesis that this population's demographics and outcomes are unique as compared with other arthroplasty patients. The National Hospital Discharge Survey provided the raw data. Individuals admitted with a primary TKA, primary THA, or revision TJA were selected. Annual rates were then calculated and demographics and outcomes compared. 30,624 patients were reviewed. The proportion of admissions for periprosthetic fractures ranged from 4.2% to 7.4% annually. As compared to patients admitted for other TJA diagnoses, individuals admitted with periprosthetic fracture were older, were more often female, were more often admitted emergently/urgently, had longer lengths of stay, had higher rates of discharge to places other than home, and had a significantly elevated mortality.

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.

Dynamic soft tissue balancing in total knee arthroplasty

Achieving optimal soft tissue balance intraoperatively is a critical element for a successful outcome after total knee arthroplasty. Although advances in navigation have improved the incidence of angular outliers, spatial distance measurements do not quantify soft tissue stability or degrees of ligament tension. Revisions caused by instability, malrotation, and malalignment still constitute up to one-third of early knee revisions. The development of integrated microelectronics and sensors into the knee trials during surgery allows surgeons to evaluate and act on real-time data regarding implant position, rotation, alignment, and soft tissue balance through a full range of motion.

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.

Influence of bicompartmental knee replacement on stand-to-sit movement

Knee osteoarthritis often occurs in medial and patellofemoral compartments. A bicompartmental knee replacement system replaces these two affected knee compartments and keeps the lateral compartment and cruciate ligaments intact. It is yet to be determined whether limbs with bicompartmental knee systems can demonstrate frontal-plane knee mechanics and hamstring coactivation similar to healthy control limbs during daily activities requiring the weight-bearing knees to bend through a large range of motion (e.g., stand-to-sit). Three-dimensional knee mechanics and quadriceps and hamstring electromyographic data were collected from 8patients with a unilateral bicompartmental knee system and 10 healthy control participants. No differences in frontal-plane knee mechanics and hamstring coactivation were found among the surgical, contralateral, and control limbs during stand-to-sit (p > .05).

Increased long-term survival of posterior cruciate-retaining versus posterior cruciate-stabilizing total knee replacements

BACKGROUND

Considerable debate remains regarding the use of posterior cruciate-retaining or posterior cruciate-stabilizing designs for total knee arthroplasty. Multiple studies have investigated kinematic, radiographic, and clinical outcomes of both. Nevertheless, long-term survivorship analyses directly comparing the two designs have not been performed, to our knowledge. Our goal was to analyze the fifteen-year survival of posterior cruciate-retaining and posterior cruciate-stabilizing total knee replacements at our institution.

METHODS

A retrospective review identified 8117 total knee arthroplasties (5389 posterior cruciate-retaining and 2728 posterior cruciate-stabilizing) that had been performed from 1988 to 1998. This range was chosen because both designs were used in high volumes at our institution during this period. Patients were followed via our total joint registry at one, two, and five years after the arthroplasty and every five years thereafter. Aseptic revision surgery was the primary end point of our analysis. Implant survival was estimated with Kaplan-Meier curves.

RESULTS

Survival at fifteen years was 90% for posterior cruciate-retaining total knee replacements, compared with 77% for posterior cruciate-stabilizing total knee replacements (p < 0.001). In knees with preoperative deformity, the fifteen-year survival was 90% for posterior cruciate-retaining total knee replacements, compared with 75% for posterior cruciate-stabilizing total knee replacements (p < 0.04). Likewise, in knees without preoperative deformity, the fifteen-year survival was 88% for posterior cruciate-retaining total knee replacements, compared with 78% for posterior cruciate-stabilizing total knee replacements (p < 0.001). After adjustment for age, sex, preoperative diagnosis, and preoperative deformity, the risk of revision was significantly lower in knees with a posterior cruciate-retaining total knee replacement (p < 0.001; hazard ratio = 0.5; 95% confidence interval, 0.4 to 0.6).

CONCLUSIONS

In evaluating the implants used at our institution for total knee arthroplasty during the study period, posterior cruciate-retaining prostheses had significantly improved survival in comparison with posterior cruciate-stabilizing prostheses at fifteen years. Furthermore, this significant difference remained when accounting for age, sex, diagnosis, and deformity.

Anteroposterior stability after posterior cruciate-retaining total knee arthroplasty

PURPOSE

A functional posterior cruciate ligament (PCL) is important for the knee stability after PCL-retaining total knee arthroplasty (TKA). The objectives of this study were to determine the anteroposterior (AP) displacement of the knee after a mobile- or fixed-bearing PCL-retaining TKA operated with a ligament-balancing technique and the correlation of AP stability with the clinical outcome.

METHODS

The AP displacement of 160 TKAs in 143 patients was measured pre- and intra-operatively, and the results were compared to the AP displacement measured 4 years post-surgery.

RESULTS

The change in AP displacement from intra-operative measurement to follow-up at the 25° measuring point was -1.2 mm; at 90°, it was -0.2 mm. Mobile bearings showed significantly greater AP displacement than fixed bearings. Older patients, male patients and patients receiving a fixed prosthesis had lower post-operative laxity compared with the overall population.

CONCLUSIONS

The small change in AP displacement indicates that the PCL remains functional over time. In our study, we could not find any correlation between knee AP stability and clinical outcome, including passive flexion, Knee Society Score or Visual Analogue Scale of pain and satisfaction.

Mobile-bearing total knee arthroplasty: a meta-analysis

An extensive database search was completed to perform a meta-analysis of outcomes of mobile-bearing total knee arthroplasty. Nineteen manuscripts encompassing 3506 total knee arthroplasty met criteria for analysis (average follow-up, 8.6 years). Data were subdivided based on design type and included rotating platform, meniscal bearing, and anterior-posterior glide-rotation subgroups. Fifteen-year survivorship of rotating platform designs (96.4%) was greater than meniscal bearing implants (86.5%). Mean component loosening (0.33%) and bearing instability (<1%) for all subgroups were uncommon. Implants placed prior to 1995 exhibited higher rates of bearing complications (1.6% vs 0.1%). Excellent results were obtained with mobile-bearing TKA over 2 decades. Loosening and bearing instability were uncommon. Bearing complications lessened after 1995, possibly secondary to improved surgical technique.

The role of the cemented all-polyethylene tibial component in total knee replacement: a 30-year patient follow-up and review of the literature

Use of an all-polyethylene tibial component in primary total knee arthroplasty remains an attractive option considering the reported durability of the construct, the lowered cost compared to modular metal-backed tibia, and the elimination of backside wear. The two major intra-operative disadvantages include the inability to alter the tibial component thickness after permanent implant placement and the inability to use varus-valgus constrained designs. The long-term disadvantage is the inability to perform a modular insert exchange should this be required. We report the 30-year outcome of a single patient using the duopatellar total knee replacement system. Based on a critical review of the literature we would recommend use in patients 80 years of age or older, consideration in patients 75 to 79 years, and possibly in younger yet less active patients. These three groups would be the least likely to require a modular tibial liner exchange in their lifetime.

The influence of procedure volumes and standardization of care on quality and efficiency in total joint replacement surgery

BACKGROUND

The relationship between surgeon and hospital procedure volumes and clinical outcomes in total joint arthroplasty has long fueled a debate over regionalization of care. At the same time, numerous policy initiatives are focusing on improving quality by incentivizing surgeons to adhere to evidence-based processes of care. The purpose of this study was to evaluate the independent contributions of surgeon procedure volume, hospital procedure volume, and standardization of care on short-term postoperative outcomes and resource utilization in lower-extremity total joint arthroplasty.

METHODS

An analysis of 182,146 consecutive patients who underwent primary total joint arthroplasty was performed with use of data entered into the Perspective database by 3421 physicians from 312 hospitals over a two-year period. Adherence to evidence-based processes of care was defined by administration of appropriate perioperative antibiotic prophylaxis, beta-blockade, and venous thromboembolism prophylaxis. Patient outcomes included mortality, length of hospital stay, discharge disposition, surgical complications, readmissions, and reoperations within the first thirty days after discharge. Hierarchical models were used to estimate the effects of hospital and surgeon procedure volume and process standardization on individual and combined surgical outcomes and length of stay.

RESULTS

After adjustment in multivariate models, higher surgeon volume was associated with lower risk of complications, lower rates of readmission and reoperation, shorter length of hospital stay, and higher likelihood of being discharged home. Higher hospital volume was associated with lower risk of mortality, lower risk of readmission, and higher likelihood of being discharged home. The impact of process standardization was substantial; maximizing adherence to evidence-based processes of care resulted in improved clinical outcomes and shorter length of hospital stay, independent of hospital or surgeon procedure volume.

CONCLUSIONS

Although surgeon and hospital procedure volumes are unquestionably correlated with patient outcomes in total joint arthroplasty, process standardization is also strongly associated with improved quality and efficiency of care. The exact relationship between individual processes of care and patient outcomes has not been established; however, our findings suggest that process standardization could help providers optimize quality and efficiency in total joint arthroplasty, independent of hospital or surgeon volume.

Cementless tibial fixation in TKA: not a second coming

Cemented total knee arthroplasty (TKA), using mechanically sound components such as the total condylar system (Johnson & Johnson, New Brunswick, New Jersey), have been performed for >25 years. Long-term follow-up studies have shown excellent durability. In 1 series with a minimum 20-year follow-up, the revision rate for aseptic loosening was 3.5%. More contemporary prostheses, such as the low contact stress rotating platform (DePuy, Warsaw, Indiana) and Kinematic Knee systems (Howmedica, Rutherford, New Jersey), have demonstrated minimal loosening at 20-year follow-up. In a minimum 20-year follow-up of a rotating platform TKA, the revision rate for aseptic loosening was 0%. In a minimum 15-year follow-up of kinematic cruciate-retaining TKA, the revision rate for aseptic loosening was 1.8%. Cemented fixation is durable and forgiving. It can accommodate defects in bone as well as imperfect cuts that are not uncommon, even in the best of hands. It can interdigitate into soft and hard bone. With the development of modular tibial trays with better locking mechanisms and less abrasive surfaces, as well as the development of more wear-resistant polyethylene (gamma irradiated in an inert environment and crosslinked polyethylene), the osteolysis that developed around first generation modular components should be markedly less with newer designs. It is for these reasons that cement should remain the fixation of choice in TKA.

The epidemiology of revision total knee arthroplasty in the United States

Understanding the cause of failure and type of revision total knee arthroplasty (TKA) procedures performed in the United States is essential in guiding research, implant design, and clinical decision making in TKA. We assessed the causes of failure and specific types of revision TKA procedures performed in the United States using newly implemented ICD-9-CM diagnosis and procedure codes related to revision TKA data from the Nationwide Inpatient Sample (NIS) database. Clinical, demographic, and economic data were reviewed and analyzed from 60,355 revision TKA procedures performed in the United States between October 1, 2005 and December 31, 2006. The most common causes of revision TKA were infection (25.2%) and implant loosening (16.1%), and the most common type of revision TKA procedure reported was all component revision (35.2%). Revision TKA procedures were most commonly performed in large, urban, nonteaching hospitals in Medicare patients ages 65 to 74. The average length of hospital stay (LOS) for all revision TKA procedures was 5.1 days, and the average total charges were $49,360. However, average LOS, average charges, and procedure frequencies varied considerably by census region, hospital type, and procedure performed.

LEVEL OF EVIDENCE

Level II, economic and decision analysis. See Guidelines for Authors for a complete description of levels of evidence.

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.

The Anatomical Graduated Component total knee replacement: a long-term evaluation with 20-year survival analysis

The long-term success of total knee replacement is multifactorial, including factors relating to the patient, the operation and the implant. The purpose of this study was to examine the 20-year survival of the cemented Anatomical Graduated Component (AGC) total knee replacement. Between 1983 and 2004, 7760 of these were carried out at our institution. Of these, 6726 knees which received the non-modular metal-backed tibial component with compression-moulded polyethylene and had a minimum two-year follow-up were available for study. In all, 36 knees were followed over 20 years with a survival of the tibial and femoral components together of 97.8% (95% confidence interval (CI) 0.9851 to 0.9677), with no implants being revised for polyethylene wear or osteolysis. Age > 70 was associated with increased survival (99.6%, 95% CI 99.0 to 99.8) (p < 0.0001) but pre-operative valgus alignment reduced survival (95.1%, 95% CI 90.0 to 97.6) (p = 0.0056). Age < 55 (p = 0.129), pre-operative varus alignment (p = 0.707), osteonecrosis (p = 0.06), rheumatoid arthritis (p = 0.247), and gender (p = 0.666) were not statistically associated with failure. We attribute the success of the AGC implant to its relatively unconstrained articular geometry and the durability of a non-modular metal-backed tibial component with compression moulded polyethylene.

Functional outcome and range of motion of high-flexion posterior cruciate-retaining and high-flexion posterior cruciate-substituting total knee prostheses. A prospective, randomized study

BACKGROUND

Although the design features of the high-flexion posterior cruciate-retaining and high-flexion posterior cruciate-substituting total knee prostheses reportedly improve the range of knee motion, a clinical comparison of both systems with regard to range of motion has not been reported, to our knowledge. The purpose of the present study was to compare the range of motion and functional outcome in knees receiving either a high-flexion posterior cruciate-retaining or a high-flexion posterior cruciate-substituting total knee prosthesis.

METHODS

Two hundred and fifty patients (mean age, 71.6 years) received a high-flexion posterior cruciate-retaining total knee prosthesis in one knee and a high-flexion posterior cruciate-substituting total knee prosthesis in the contralateral knee. Ten patients were men, and 240 were women. At the time of each follow-up (minimum duration of follow-up, two years; mean, 2.3 years), the patients were assessed clinically and radiographically with use of the knee-rating systems of the Knee Society and the Hospital for Special Surgery. In addition, each patient completed the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) questionnaire. Non-weight-bearing and weight-bearing ranges of knee motion were determined in both groups.

RESULTS

The mean postoperative Knee Society knee score was 94 points for the knees treated with a high-flexion cruciate-retaining prosthesis and 95 points for those treated with a high-flexion posterior cruciate-substituting prosthesis. The mean postoperative Hospital for Special Surgery knee score was 90 points for the knees that had been treated with a high-flexion posterior cruciate-retaining prosthesis and 91 points for those that had been treated with the high-flexion posterior cruciate-substituting prosthesis. At the time of the latest follow-up, the knees that had been treated with a high-flexion posterior cruciate-retaining prosthesis had a mean non-weight-bearing range of motion of 133 degrees and a mean weight-bearing range of motion of 118 degrees. The knees that had been treated with a high-flexion posterior cruciate-substituting prosthesis had a mean non-weight-bearing range of motion of 135 degrees and a mean weight-bearing range of motion of 122 degrees. No knee had aseptic loosening, revision, or osteolysis.

CONCLUSIONS

After a minimum duration of follow-up of two years, there was no difference in range of motion or clinical and radiographic results between knees that had received a high-flexion posterior cruciate-retaining total knee prosthesis and those that had received a high-flexion posterior cruciate-substituting total knee prosthesis.

A comprehensive joint replacement program for total knee arthroplasty: a descriptive study

Background

Total knee arthroplasty (TKA) is a commonly performed surgical procedure in the US. It is important to have a comprehensive inpatient TKA program which maximizes outcomes while minimizing adverse events. The purpose of this study was to describe a TKA program – the Joint Replacement Program (JRP) – and report post-surgical outcomes.

Methods

74 candidates for a primary TKA were enrolled in the JRP. The JRP was designed to minimize complications and optimize patient-centered outcomes using a team approach including the patient, patient's family, and a multidisciplinary team of health professionals. The JRP consisted of a pre-operative class, standard pathways for medical care, comprehensive peri-operative pain management, aggressive physical therapy (PT), and proactive discharge planning. Measures included functional tests, knee range of motion (ROM), and medical record abstraction of patient demographics, length of stay, discharge disposition, and complications over a 6-month follow-up period.

Results

All patients achieved medical criteria for hospital discharge. The patients achieved the knee flexion ROM goal of 90° (91.7 ± 5.4°), but did not achieve the knee extension ROM goal of 0° (2.4 ± 2.6°). The length of hospital stay was two days for 53% of the patients, with 39% and 7% discharged in three and four days, respectively. All but three patients were discharged home with functional independence. 68% of these received outpatient physical therapy compared with 32% who received home physical therapy immediately after discharge. Two patients (< 3%) had medical complications during the inpatient hospital stay, and 9 patients (12%) had complications during the 6-month follow-up period.

Conclusion

The comprehensive JRP for TKA was associated with satisfactory clinical outcomes, short lengths of stay, a high percentage of patients discharged home with outpatient PT, and minimal complications. This JRP may represent an efficient, effective and safe protocol for providing care after a TKA.

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.

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.

Midterm results with the PFC Sigma total knee arthroplasty system

We prospectively studied 207 consecutive patients (284 knees) undergoing total knee arthroplasty (June 1996 to December 1997) with a cemented tricompartmental Sigma PFC (DePuy Orthopaedics, Warsaw, Ind) total knee arthroplasty via a standard procedure (median follow-up, 87 months). Cruciate-retaining (272 knees, 96%) and cruciate-substituting (12, 4%) implants were used. There was one revision secondary to a ligament disruption after a fall. No implants were radiographically loose or at risk for loosening. Radiolucencies (none>2 mm or progressive) were shown on anteroposterior (7% of medial tibias) and lateral (17% of posterior femora) radiographs. Knee Society pain scores improved significantly (preoperative median, 20 points; postoperative median, 50 points [P<.001]). The PFC Sigma Knee system has excellent midterm durability.

Relationship between bone ingrowth, mineral apposition rate, and osteoblast activity

To better understand skeletal attachment of porous coated total hip and knee implants over time, this study investigated the dynamics of osteoblast populations at the interface of porous coated implants in a weight-bearing ovine model. The relationship between cancellous bone ingrowth, mineral apposition rate (MAR), and osteoblast activity indicators such as osteoblast area, relative osteoblast number, osteoid width, and osteoid area (O.Ar.) were investigated. The data demonstrated that the percent O.Ar. was a marginally significant predictor of bone ingrowth and MAR over time, suggesting that the amount of osteoid present influenced bone ingrowth and MAR in the porous coated implants. The data also demonstrated that all osteoblast activity indicators were significantly greater in the porous coated region compared to the host bone region, while controlling for in situ time (p < 0.05). This may have been due to the trauma of implantation or the influence of the implant load on the bone tissue promoting a regional acceleratory phenomenon. The localized response suggests that specific therapies may be developed to affect the physiology of osteoblasts at the interface of implants, which may allow for improve skeletal attachment of biomaterials and clinical outcomes of cementless joint replacements.

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.

A new patellofemoral scoring system for total knee arthroplasty

Patellofemoral complications after total knee arthroplasty (TKA) can result in substantial dissatisfaction with the procedure for some patients. In assessing outcomes of TKA, however, there is often a discrepancy between patellofemoral symptoms and the results obtained by conventional scoring and radiographic analysis. We asked whether a new scoring system and weightbearing radiographic view would more accurately represent patellofemoral kinematics and explain related complications. Sixty-nine patients (100 knees) who underwent posterior-stabilized TKA between 1994 and 1997 were included for clinical and radiographic evaluation. A new patella score was developed to rapidly determine complications, ranged from 0 to 100 points, and included ratings for subjective and objective aspects of TKA. A new weight-bearing axial radiographic view was devised by positioning the standing patient in a semisquatted position. Measurements for patella alignment (tilt and subluxation) were performed. Preoperative Knee Society knee and function scores were 43 +/- 5 points, and 39 +/- 15 points, respectively. Postoperatively, scores increased to 93 +/- 8 and 89 +/- 8 points, respectively. The patella score averaged 89 +/- 8 points and showed satisfactory interobserver variability. The new weightbearing radiographic view demonstrated sources of patellofemoral symptoms. We report a new scoring system and weightbearing view that are easy to use and more accurately represent patellofemoral kinematics than do conventional methods of analysis.

[Mid-term results of Wallaby I posterior cruciate retaining total knee arthroplasty: a prospective study of the first 425 cases]

PURPOSE OF THE STUDY

Posterior Wallaby I is a fixed polyethylene tibial plateau prosthesis enabling preservation of the posterior cruciate ligament (PCL). Its asymmetrical and divergent femoral condyles articulate with also asymmetrical tibial plateaus. The purpose of this prospective study was to analyze outcome of the first 425 Wallaby I prosthesis of the Guepar group implanted for first-intention treatment.

MATERIALS AND METHODS

These 425 prostheses were implanted from December 1992 to February 1995 by senior and junior surgeons. Mean patient age at implantation was 70.5 years. 91% had primary or secondary osteoarthritis and only 8.9% had inflammatory rheumatoid disease. The mean preoperative IKS score was 25.34 points and the IKS function score was 29.04. 10.35% of knees were aligned normally (mechanical axis between 2 degrees varus and 3 degrees valgus) according to the IKS criteria (Ewald), 24% presented valgus > or = 4 degrees and 65.6% varus > or = 3 degrees. All tibial and patellar components (except one) were cemented, 5.8% of the femoral pieces were inserted without cement. All but 11 patellae were resurfaced. Clinical outcome was assessed with the IKS score and radiological outcome with the IKS criteria. The patella was considered to be tilted when the alpha angle was > 5 degrees and dislocated when the AA' distance was > 5 mm. The chi-square test was used for comparison of quantitative variables (significance set at 0.05).

RESULTS

Early postoperative complications were rare: two infections cured with debridement-lavage and antibiotics without removal of the prosthesis, one peronal nerve palsy which regressed partially, ten late unions without clinical consequence (particularly in the inflammatory rheumatoid patients). Twenty-six prostheses were followed less than one year (eight patients died and eighteen were lost to follow-up) and 84 less than five years (27 patients died and 57 lost to follow-up before five years). 315 prostheses were followed for more than five years (5-9 years) with a mean follow-up of 6.3 years. Among the 399 prostheses followed for one year or more, we noted: four infections including three requiring change of the prosthesis (one cured by arthroscopic lavage), two aseptic loosenings which were revised (one global one tibial), one tibial loosening and three patellar loosenings which were not revised, and two femoral ossifications limiting joint motion but improved by arthrolysis and resection of the ossifications. Three patients experienced anterior pain requiring secondary patellar resurfacing in two and section of the lateral patellar wing in one. Ninteen patellar fractures (4.7%) were noted, including 17 with no significant functional impact which were not revised. The mean IKS knee score among prostheses followed for five years was 90.5 points, with mean motion 110.5 degrees. Mean IKS function score was 61.63 points. 72.9% of the knees were aligned, 22.2% in varus and 4.9% in valgus. The mechanical axis of 94.3% of the knees was between 5 degrees varus and 5 degrees valgus. Prosthesis survival at eight years (Kaplan-Meier method) was 97.7% considering all reasons for prosthesis removal and 98.5% for removal for aseptic loosening.

CONCLUSION

This prospective multicentric study demonstrated that the results obtained with the Wallaby I prosthesis are as good as those obtained with other prostheses sparing the PCL and published in the literature. Preservation of the PCL enables better knee stability, correct motion (110.5 degrees in our series) with almost no radiological wear of the tibial polyethylene at eight years. The only worrisome complication is patellar fracture.

Rotating platform knees: an emerging clinical standard: in opposition

As surgeons, we share the common goals of making total knee arthroplasty as reliable, as reproducible, and as durable as we can. For that reason, we are almost compelled to investigate the rotating platform knee because of the contentions that it might improve patellar tracking, decrease lateral release rates, improve flexion, or perhaps give better wear characteristics over the long term. But when we take a step back and carefully examine the scientific data from 20 years of clinical experience with the rotating platform knee, the data speak for itself. To date, there are no demonstrated clinical advantages in regard to wear, survivorship, kinematics, range of motion, or patellar function. The rotating platform design then is really just another knee design, clinically indistinguishable from many well-functioning, fixed-bearing total knee designs.

Surface cementation of stemmed tibial components in primary total knee arthroplasty: minimum 5-year follow-up

Cement remains the "gold standard" for fixation in total knee arthroplasty. Between 1991 and 1998, 128 consecutive knees in 109 patients underwent primary cemented total knee arthroplasty using a surface cementation technique. The average follow-up was 95 (range, 63-155) months. Preoperative range of motion (ROM) averaged 5 degrees to 111 degrees which improved to 1 degrees to 116 degrees postoperatively. Modified Hospital for special surgery score (HSS) scores improved from 61 (range, 47-76) to 97 (range, 81-100) and the corresponding Knee Society Scores from 122 (range, 94-152) to 195 (range, 162-200). No osteolytic lesions were found; however, 3 tibias had radiolucent lines which were asymptomatic, nonprogressive, and not associated with implant failure. The average depth of penetration of cement was 2.7 mm. One knee (1%) required revision surgery for femoral loosening, and 1 required revision of the polyethylene liner. The present cementation technique provides excellent durable results at midterm follow-up.

International multi-centre survivorship analysis of mobile bearing total knee arthroplasty

We retrospectively reviewed the experience of a large international multi-centre study of primary total knee arthroplasty with mobile bearing design and modifications of the tibial component to allow for bicruciate preservation, posterior cruciate retention, or sacrifice. Twenty-seven surgeons performed 4,743 total knee replacements between 1981 and 1997. Implants inserted were 324 that retained both cruciate ligaments, 2,165 that retained the posterior cruciate, and 2,254 that sacrificed both cruciates. The patella was resurfaced in 2,838 and unresurfaced in 1,905. With failure defined as revision or reoperation for any reason, the overall survivorship was 79% at 16 years' follow-up. Revision occurred in 259 (5.4%) knees out of the entire cohort. The risk adjusted rates of failure were higher in females, younger patients, osteoarthritis, post-traumatic arthritis, and in patients who had a meniscal bearing prosthesis or patellar resurfacing. The most common cause of revision was bearing-related issues including chronic instability, bearing subluxation, bearing dislocation, or bearing wear in 2.3%.

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.

Choosing your implant: cemented, tricompartmental, and posterior stabilized

Cemented, posterior-stabilized, tricompartmental implants have yielded excellent relief of pain and are applicable to almost all clinical situations. The complications and revision rates after routine patellar resurfacing are less than those seen without such resurfacing. Cine fluoroscopic studies have shown that they restore a more normal kinematic pattern than do posterior cruciate ligament-retaining implants and have a low rate of radiographic and/or clinical loosening when followed up through 15 years after surgery. Latest posterior stabilized designs can allow a higher degree of flexion than seen in any other combination of implant designs. It is for all these reasons that the author feels that this method of performing a knee arthroplasty is the gold standard.

Sagittal laxity in vivo after total knee arthroplasty

INTRODUCTION

A stress arthrometry study of 77 knees undergoing total knee arthroplasty was performed to determine the difference in anteroposterior (AP) laxity between posterior cruciate ligament (PCL)-retaining (PCLR) and PCL-substituting (PCLS) prostheses using the Genesis I TKA.

MATERIALS AND METHODS

Fifty-three knees had PCLR and 24 had PCLS prostheses. The selected patients had successful arthroplasties after a minimum follow-up of 5 years. AP laxity was measured with a KT-2000 arthrometer (Medmetric, San Diego, CA, USA) using standard protocols.

RESULTS

At 30 degrees of flexion, there was no statistical difference in anterior (PCLR: 4.7 mm, PCLS: 4.5 mm), posterior (PCLR: 1.1 mm, PCLS: 0.7 mm), or total (PCLR: 5.8 mm, PCLS: 5.3 mm) displacement. At 75 degrees , significant differences were seen in both anterior (PCLR: 3.3 mm, PCLS: 2.3 mm) and total (PCLR: 4.8 mm, PCLS: 3.4 mm) displacement (p=0.001 and p=0.009, respectively), although there was no statistical difference in posterior displacement (PCLR: 1.5 mm, PCLS: 1.1 mm).

CONCLUSION

The above values are considered the suitable degree of AP laxity in total knee arthroplasty for a satisfactory clinical outcome 5-9 years after surgery. The PCL in a PCLR prosthesis and the central tibial spine and femoral cam in a PCLS prosthesis might play comparable roles in determining the laxity in the posterior direction in these prostheses.

Implant survivorship and complication rates after total knee arthroplasty with a third-generation cemented system: 5 to 8 years followup

We evaluated implant survivorship, reoperation rates, and complication rates of a group of patients who had total knee arthroplasty with a third-generation cemented prosthetic device using cruciate-retaining and posterior-stabilized designs at 5 to 8 years followup. Three hundred thirty-four consecutive primary total knee arthroplasties (186 cruciate retaining and 148 posterior stabilized) were done in 287 patients at our institution during a 2-year period. Kaplan Meier survivorship using revision for any reason and revision for aseptic loosening as endpoints were 95.9% and 99.5% respectively at 8 years. Nine patients (four with cruciate-retaining total knee arthroplasties, five with posterior-stabilized total knee arthroplasties; 3.1%) had reoperations for any reason. No patients had reoperation for problems related to the patellofemoral joint. Thirty-two patients (11.1%) had intraoperative or postoperative complications. There were no differences in any of the outcomes analyzed between patients who had cruciate-retaining or posterior-stabilized total knee replacements. Our results show that with appropriate patient selection and meticulous attention to surgical technique, excellent clinical and radiographic results can be achieved with a third-generation total knee arthroplasty system at intermediate followup.

LEVEL OF EVIDENCE

Therapeutic study, Level III-2 (retrospective cohort study).

Total knee arthroplasty for patients 90 years of age and older

This study was done to review the reliability, durability, and safety of primary and revision total knee arthroplasty for patients 90 years of age and older. Because little data exist about the safety or efficacy of total knee replacement in this elderly population some physicians may be hesitant to recommend elective surgery to patients of this age. Fifty-one total knee replacements were done for 41 patients age 90 to 102 years (mean, 92 years). Forty-four primary total knee replacements and seven revision total knee replacements were done. Each patient was followed up until death or for a minimum of 2 years (mean, 4.0 years). The Knee Society pain scores improved significantly for the primary and revision groups from preoperative mean scores of 30 and 29 points to latest followup scores of 86 and 87 points, respectively. One patient died in the early postoperative period of causes related to the operation. The remaining patients have lived an average of 4.4 +/- 2.2 years after the primary knee arthroplasties and 5.7 +/- 2.8 years after the revision knee arthroplasties. No knees have required revision subsequently. Total knee replacement was reliable, durable, and safe in this group of patients older than 90 years. Primary care physicians and surgeons should be aware that primary and revision total knee replacement can be done safely and effectively for patients 90 years and older and result in years of marked pain relief for those patients.

Total knee arthroplasty in patients with a prior fracture of the tibial plateau

BACKGROUND

A fracture of the tibial plateau may predispose the knee to the development of posttraumatic arthritis. Malunion, intra-articular chondro-osseous defects, limb malalignment, retained internal fixation devices, and poor surrounding soft tissues may in turn compromise the outcome of total knee arthroplasty. The aim of our study was to evaluate the results of total knee arthroplasty in patients with a previous fracture of the tibial plateau.

METHODS

The results of sixty-two condylar total knee arthroplasties performed with cement, from 1988 to 1999, in sixty-two patients with a previous fracture of the tibial plateau were reviewed. The fracture of the tibial plateau had been treated by open reduction and internal fixation in thirty-eight knees, external fixation in one knee, and nonoperatively in twenty-three knees. There were forty women and twenty-two men with an average age of sixty-three years at the time of the arthroplasty. Knee Society scores were recorded preoperatively and at the time of follow-up, at an average of 4.7 years, and complications were noted. No patient was lost to follow-up.

RESULTS

The mean Knee Society scores improved significantly (p < 0.0001), from 43.9 points for pain and 52 points for function preoperatively to 82.9 and 84 points, respectively, at the time of the latest follow-up. There were thirteen reoperations, which included manipulation with the patient under anesthesia (five knees), wound revision (three knees), and component revision (five knees). There were six intraoperative complications (10%). A postoperative complication occurred in sixteen knees (26%).

CONCLUSIONS

The vast majority of patients treated with total knee arthroplasty after a previous fracture of the tibial plateau have substantial improvement in function and relief of pain. However, these patients are at increased risk for perioperative complications, as evidenced by the high reoperation rate of 21% in this study.

Above-knee amputation after recurrent dislocations of total knee arthroplasty

Amputation after total knee arthroplasty (TKA) is an extremely rare but disastrous complication. Most of the reported cases resulted from refractory deep joint sepsis or perioperative vascular complications. We present a case of above-knee amputation resulting from vascular complications after recurrent dislocations of a TKA in a patient with underlying end-stage renal disease. The possible association between certain metabolic diseases and instability of TKA is discussed. In contrast to the high incidence of vascular complications after traumatic knee dislocation, popliteal artery injury after TKA dislocation is seldom encountered. The importance of careful evaluation and serial physical examinations to exclude the possibility cannot be overemphasized, however. When compromise of the circulation was recognized, emergent exploration of the popliteal fossa for repair of the vascular injury presented the best chance to save the limb.

Repairing large porcine full-thickness defects of articular cartilage using autologous chondrocyte-engineered cartilage

Large full-thickness defects of articular cartilage remain a major challenge to orthopedic surgeons because of unsatisfactory results of current therapy. Many methods, such as chondrectomy, drilling, cartilage scraping, arthroplasty, transplantation of chondrocytes, periosteum, perichondrium, as well as cartilage and bone, have been tried to repair articular cartilage defects. However, the results are far from satisfactory. In this study, we applied a tissue-engineering approach to the repair of articular cartilage defects of knee joints in a porcine model. Using isolated autologous chondrocytes, polyglycolic acid (PGA), and Pluronic, we have successfully in vivo-engineered hyaline cartilage and repaired articular cartilage defects. The surface of the repaired defects appeared smooth at 24 weeks postrepair. Histological examination demonstrated a typical hyaline cartilage structure with ideal interface healing between the engineered cartilage and the adjacent normal cartilage and underlying cancellous bone. In addition, glycosaminoglycan (GAG) levels in the engineered cartilage reached 80% of that found in native cartilage at 24 weeks postrepair. Biomechanical analysis at 24 weeks demonstrated that the biomechanical properties of the tissue-engineered cartilage were improved compared with those at an earlier stage. Thus, the results of this study may provide insight into the clinical repair of articular cartilage defects.

Ten steps to an easier revision total knee arthroplasty

Revision total knee arthroplasty can be facilitated by proper preoperative planning, using an extensile incision, lysing of adhesions on the lateral gutter, exposing the medial and lateral aspects of the proximal tibia, and stabilizing the patellar tendon. If the patella cannot be everted safely, the surgeon should be prepared to do a rectus snip or tibial tubercle osteotomy. The components should be extracted axially after separation of the interfaces with a small sagittal saw or small osteotomes. The intramedullary canals of the femur and tibia should be used as references for the cutting blocks.