Femoral and tibial component rotation in total knee arthroplasty: methods and consequences

At least four ways have been described to determine femoral component rotation, and three ways to determine tibial component rotation in total knee replacement (TKR). Each method has its advocates and each has an influence on knee kinematics and the ultimate short and long term success of TKR. Of the four femoral component methods, the author prefers rotating the femoral component in flexion to that amount that establishes a stable symmetrical flexion gap. This judgement is made after the soft tissues of the knee have been balanced in extension. Of the three tibial component methods, the author prefers rotating the tibial component into congruency with the established femoral component rotation with the knee is in extension. This yields a rotationally congruent articulation during weight-bearing and should minimise the torsional forces being transferred through a conforming tibial insert, which could lead to wear to the underside of the tibial polyethylene. Rotating platform components will compensate for any mal-rotation, but can still lead to pain if excessive tibial insert rotation causes soft-tissue impingement.

The evolving incidence and reasons for re-operation after fixed-bearing PCL retaining total knee arthroplasty

PCL retaining fixed-bearing TKA is a highly successful operation with the need for more surgery occurring at the rate of approximately 0.4% per year over the first 27 years. The most common cause for revision surgery is related to polyethylene insert failure and accounts for approximately 50% of re-operations. Late metastatic infection is the next most frequent cause followed by patellar problems, late instability and component loosening in decreasing frequency. A myriad of rare miscellaneous problems can also occur.

Self-expanding metal stent insertion for inoperable esophageal carcinoma in Belfast: an audit of outcomes and literature review

Successful palliation of dysphagia in patients with inoperable esophageal carcinoma has a major effect on quality of life. Self-expanding metal stents (SEMS) are currently recommended for rapid symptomatic relief when life expectancy is less than 3 months. We assessed complication and reintervention rates along with survival outcomes in patients with inoperable esophageal carcinoma undergoing stent insertion. A retrospective audit was performed from April 2007 to June 2009 for all inoperable primary esophageal carcinoma patients who had an esophageal stent inserted for dysphagia. Case notes were reviewed for clinical, pathological, stent and complication details, while ICD-10 causes of death were obtained from the Department of Health and Social Services, Northern Ireland. Fifty-six stents were inserted into 53 patients (66.0% male, mean age of 70 years). Inoperability was defined by metastatic spread (n= 34, 64.2%), locally advanced disease (n= 7, 13.2%), and severe medical comorbidities (n= 12, 22.6%). The median time from diagnosis to stent insertion was 109 (interquartile range [IQR] 43-187) days. Fifty stents (94.3%) were successfully deployed, while three patients (5.7%) required an additional stent as the primary stent had not bridged the tumor (proximal deployment = 2, suboptimal stent length = 1). Post-SEMS dysphagia scores were significantly better than pre-SEMS scores (2.90 vs. 1.54, P < 0.001). There were 27 complications identified in 23 (43.4%) patients (major complications = 9, minor complications = 14). Twelve patients (22.6%) required additional endoscopic procedures. The 30-day mortality rate was 11.3% (n= 6). Only one patient (1.9%) remains alive with a cumulative median survival rate of 84 (IQR 38-156) days. Esophageal stent insertion in this group of patients still presents a clinical challenge, with complication and endoscopic reintervention rates of 43.4 and 22.6%, respectively. Our results are comparable with previously published series, and as a palliative modality stent insertion remains appropriate when expected survival is less than 3 months. A range of SEMS is currently available with broadly similar efficacy and safety profiles. Data regarding the newly available fully covered SEMS suggest that they should be avoided.

Measuring the economic costs of antimicrobial resistance in hospital settings: summary of the Centers for Disease Control and Prevention-Emory Workshop

Health systems administrators and clinicians need refined calculations of the attributable cost of infections due to drug-resistant microorganisms to develop and assess cost-effective prevention strategies that deal with these infections. To date, however, efforts to provide this information have yielded widely variable and often conflicting estimates. This lack of reproducibility is largely attributable to problems in study design and in the methods used to identify and measure costs. Addressing these methodological issues was the focus of a workshop that included participants from a broad range of backgrounds, including economics, epidemiology, health care management, health care outcomes research, and clinical care. This workshop summary presents the advantages and disadvantages of various research designs as well as particular methodological issues related to the measurement of the economic cost of resistance in health care settings. Suggestions are made for needed common definitions and approaches, study areas for future research are considered, and priority investigations are identified.

Tibial osteotomy coincident with long stem total knee arthroplasty: a surgical technique

Tibial deformity secondary to previous fracture or osteotomy requires corrective osteotomy in some patients undergoing total knee arthroplasty (TKA). This can be performed in either two stages or coincident with the arthroplasty. Literature on coincident tibial osteotomy and TKA has been published previously, but details of the complicated surgical technique are lacking for surgeons performing this procedure for the first time. This article details the preoperative planning involved and the intraoperative technique used in tibial osteotomy coincident with TKA.

Applying economic principles to health care

Applying economic thinking to an understanding of resource use in patient care is challenging given the complexities of delivering health care in a hospital. Health-care markets lack the characteristics needed to determine a "market" price that reflects the economic value of resources used. However, resource allocation in a hospital can be analyzed by using production theory to determine efficient resource use. The information provided by hospital epidemiologists is critical to understanding health-care production processes used by a hospital and developing economic incentives to promote antibiotic effectiveness and infection control.

Persistent limp after total hip replacement: one step at a time

A limp can be a significant sign of serious pathology about the hip. The source of the limp can be the hip or remote from the hip. Careful evaluation of each individual patient can lead to the discovery of the cause and, hopefully, its resolution.

A comparison of 4 intraoperative methods to determine femoral component rotation during total knee arthroplasty

A total of 100 consecutive posterior cruciate-retaining total knee arthroplastics were performed in 81 patients with an average age of 69 years by 1 surgeon. Diagnoses included osteoarthritis in 93 knees and rheumatoid arthritis in 7 knees. The femoral alignment necessary to create a rectangular flexion gap was determined and compared with Whiteside's line, the transepicondylar axis, and a line in 3 degrees of external rotation relative to the posterior condyles of the femur. The transepicondylar axis most consistently recreated a balanced flexion space, whereas 3 degrees of external rotation off the posterior condyles was least consistent, especially in valgus knees.

Total knee arthroplasty with posterior cruciate retention in patients with rheumatoid arthritis

The objective of the present study was to evaluate posterior cruciate ligament retention in total knee arthroplasty for patients with rheumatoid arthritis to determine long term ligamentuous stability. The study concerns an average 11-year followup (range, 10-13 years) of 52 patients (81 knees) with rheumatoid arthritis who had a total knee arthroplasty using a contemporary posterior cruciate retaining prosthesis. Particular attention was given to component survivorship and clinical stability. Fourteen patients (20 knees) died; none of these patients required revision surgery. No patients were lost to followup. Sixty-one knees in 38 patients were examined. In this group, the Knee Society knee score averaged 95 points (range, 63-100 points) and function score averaged 74 points (range, 0-100 points). Postoperative flexion averaged 112 degrees and extension averaged 0 degree. Four knees had 3 degrees asymptomatic hyperextension; one knee with 5 degrees hyperextension occasionally gave way. Five well aligned knees had between 6 degrees and 9 degrees varus or valgus laxity in extension, but no patient reported subjective instability. Two patients underwent revision surgery. One patient had a worn metal backed patella component replaced and the other patient had an open synovectomy for recurrent active rheumatoid synovitis. Thirteen-year survivorship based on need for revision surgery was 97% with the 95% confidence limits between 88% and 100%. There was no radiographic loosening or subsidence of prosthetic components. At 11-year followup, patients with rheumatoid arthritis whose knees were replaced with posterior cruciate retention prostheses experienced results equivalent to or better than those reported for patients with osteoarthritis at a similar followup. Late hyperextension and subsequent instability may be a concern in the second decade of followup.

Selective patellar nonresurfacing in total knee arthroplasty. 10 year results

Patella nonresurfacing in total knee arthroplasty was reviewed retrospectively in 49 knees (42 patients). Thirteen patients (17 knees) died leaving 29 patients (32 knees) in the final study group. The minimum length of followup was 10 years and averaged 11.7 years (range, 10-13.4 years). The diagnosis was primary osteoarthritis in 26 knees, posttraumatic arthritis in four, osteonecrosis in one, and Paget's disease in one. Patients were evaluated using the Knee Society score, a patella score, and radiographs. The mean Knee Society score improved from 52.8 to 87.5 points postoperatively and functional score improved from 57.5 to 84.5 points postoperatively. Anterior knee pain was reported in six knees (20%). Only one patient required secondary resurfacing of the patella because of postoperative anterior knee pain. No significant correlation was found between anterior knee pain and patellofemoral joint space, patellar sclerosis, Insall-Salvati ratio, patellar tilt, gender, obesity, or age. Based on the need for secondary patellar resurfacing because of anterior knee pain, the 10-year survival was 97.5%. At minimum 10-year followup, retaining the patella in total knee arthroplasty in selected patients with osteoarthritis of the osteoarthritic knee can yield acceptable results.

The Ranawat Award. Femoral component rotation during total knee arthroplasty

One-hundred consecutive posterior cruciate retaining total knee arthroplasties were performed by one surgeon in 81 patients with an average age of 69 years. Diagnoses included osteoarthritis in 93 knees and rheumatoid arthritis in seven. The femoral alignment necessary to create a rectangular flexion gap was determined and compared with Whiteside's line, the transepicondylar axis, and a line in 3 degrees external rotation relative to the posterior condyles of the femur. The transepicondylar axis most consistently recreated a balanced flexion space whereas 3 degrees external rotation off the posterior condyles was least consistent especially in knees in valgus.

Kneeling ability after total knee arthroplasty. Perception and reality

Kneeling as one of the knee's capabilities required for many activities of daily living has not been examined in detail after total knee replacement. The purpose of the present study was to question the patients' ability to kneel and their perception of factors affecting this ability after total knee arthroplasty, and to objectively assess their kneeling ability. Seventy patients with 100 total knee arthroplasties were asked to comment on their ability to kneel. Thirty-one patients with 44 knees said they could kneel easily, 29 patients with 41 knees said they were able to kneel but avoided doing so, and 10 patients with 15 knees said they were unable to kneel. Regarding observed kneeling ability, all patients were able to kneel under supervision: 56 patients with 82 knees knelt easily and got up easily from this position, 11 patients with 14 knees showed slight difficulties in kneeling or in getting up, and three patients with four knees had marked difficulties with kneeling. The patients' perceived ability to kneel after total knee arthroplasty was less than their observed ability. Fear of harming the prosthesis and lack of information prevented kneeling in 49% of the patients (27 of 56 knees) with perceived inability to kneel. Of those patients with observed difficulty in kneeling, scar pain and back related problems seemed to be major factors in limiting the kneeling ability. Kneeling, as an important function of the knee, should be given additional consideration in relation to the functional results of total knee arthroplasty. Patients should be counseled regarding factors affecting future ability to kneel.

Total knee arthroplasty in patients with rheumatoid arthritis. An overview

Total knee arthroplasty in patients with rheumatoid arthritis presents several unique challenges. Patients with rheumatoid arthritis often have additional medical, anesthetic, and global musculoskeletal problems that are not present in the patient with osteoarthritis. In terms of the knee, these patients usually have osteopenia and may present with an array of bone and soft tissue deformities, each of which can impact the initial success and long term durability of a total knee replacement. Despite these potential difficulties, the early and long term results of total knee arthroplasty in patients with rheumatoid arthritis have proven to be excellent.

Synovial cyst of the proximal tibiofibular joint with peroneal nerve compression after total knee arthroplasty

Synovial or ganglion cysts of the proximal tibiofibular joint are less common than synovial cysts of the knee joint but may present in a similar manner and may be difficult to diagnose clinically. Although synovial cysts arising from the knee joint after prosthetic arthroplasty have already been described, we report a case in which a lateral knee mass compressing the peroneal nerve was found to be a synovial cyst arising from the tibiofibular joint.

Humeral hemiarthroplasty of the elbow joint in young patients with rheumatoid arthritis: a report on 7 arthroplasties

This article evaluates the early results of 7 humeral hemiarthroplasties of the elbow joint in 5 female rheumatoid patients using only the humeral component of the capitellocondylar prosthesis. The follow-up period was 25 to 109 months. All patients were 50 years old or younger; 3 patients were between 22 and 26 years. Because all patients were rather young, the intention was to perform a procedure that conserves a maximal amount of bone stock for future salvage procedures. One prosthesis had to be removed because of an infection unrelated to the primary procedure. The remaining bone stock provided a stable and pain-free excision arthroplasty. The other arthroplasties showed good pain relief; however, postoperative motion was not as reliable as described for total capitellocondylar prostheses.

Prodromes of failure in total knee arthroplasty

A total of 102 revision total knee arthroplasties (TKAs) were reviewed to determine the prodromal symptoms and radiographic findings associated with failure. Presenting symptoms included pain (84%); swelling (76%); progressive varus or valgus deformity (19%); instability (17%); stiffness (17%); clicking or grinding (7%); catching (4%); and patellar pain, subluxation, or clicking (4%). Radiographs were diagnostic in 91% of cases, demonstrating complete radiolucencies (80%), polyethylene wear (43%), component breakage (5%), metallic debris (3%), patellar subluxation or dislocation (4%), and osteolysis (4%). Gross intraoperative findings included polyethylene wear (72%), osteolysis (22%), metal-wear synovitis (9%), component breakage (6%), patellar wear and dissociation (4%), and occult sepsis (5%). The average duration of symptoms was 13 months; the interval between orthopedic evaluations averaged 23 months. Based on this information, we recommend that an annual questionnaire and weight-bearing radiographs be used to ensure adequate surveillance of TKA patients and avoid complications associated with delay in diagnosis of polyethylene wear or implant loosening.

In vivo anteroposterior femorotibial translation of total knee arthroplasty: a multicenter analysis

A study was conducted to determine in vivo femorotibial contact patterns for subjects having a posterior cruciate retaining or posterior cruciate substituting total knee arthroplasty. Femorotibial contact of 72 subjects implanted with a total knee replacement, performed by five surgeons, was analyzed using video fluoroscopy. Thirty-one subjects were implanted with a posterior cruciate retaining total knee replacement with a flat polyethylene posterior lipped insert, 12 with a posterior cruciate retaining total knee replacement with a curved insert, and 29 with a posterior cruciate substituting total knee replacement. Each subject performed successive deep knee bends to maximum flexion. Video images at 0 degree, 30 degrees, 60 degrees, and 90 degrees flexion were downloaded onto a workstation computer. Femorotibial contact paths were determined for the medial and lateral condyles using an interactive model fitting technique. Femorotibial contact anterior to the tibial midline in the sagittal plane was denoted as positive and contact posterior was denoted as negative. Analysis of average femorotibial contact pathways of both posterior cruciate retaining designs revealed posterior femorotibial contact in full extension with anterior translation of femorotibial contact commonly observed in midflexion and terminal flexion. In posterior cruciate substituting designs, anterior femoral translation was seen medially at 30 degrees to 60 degrees flexion but rarely was observed laterally. Posterior femoral rollback laterally from full extension to 90 degrees flexion was seen in 100% of subjects implanted with a posterior cruciate substituting total knee replacement, versus 51.6% (posterior lipped polyethylene insert) and 58.3% (curved insert) of those with a posterior cruciate retaining total knee replacement. Data from this multicenter study are remarkably similar to previous fluoroscopy data from a single surgeon series, showing a lack of customary posterior femoral rollback in both posterior cruciate retaining designs, and conversely showing an average anterior femoral translation with knee flexion. Posterior femoral rollback, less than in normal knees, routinely was observed in posterior cruciate substituting total knee arthroplasty, attributed to engagement of the femoral component cam with the tibial post. The abnormal anterior femoral translation observed in posterior cruciate retaining total knee arthroplasty may be a factor in premature polyethylene wear observed in retrieval studies.

Total knee arthroplasty in Paget's disease: technical problems and results

Eleven total knee arthroplasties performed in 10 patients with Paget's disease were reviewed at 2 to 16 years postoperatively. Cemented total knee arthroplasties were performed in all cases. Range of motion improved by 21 degrees postoperatively and the follow-up Knee Society score averaged 83 points. One knee was rated poor with a score <70 points; this knee was the only knee with a loose component. All components resting on pagetic bone had a solid interface on radiographic review at an average of 5.7 years postoperatively. Although technical difficulties are encountered in achieving correct alignment and exposing the knee with local Paget's disease, good long-term outcome can be achieved.

In vivo anteroposterior femorotibial translation of total knee arthroplasty: a multicenter analysis

A study was conducted to determine in vivo femorotibial contact patterns for subjects having a posterior cruciate retaining or posterior cruciate substituting total knee arthroplasty. Femorotibial contact of 72 subjects implanted with a total knee replacement, performed by five surgeons, was analyzed using video fluoroscopy. Thirty-one subjects were implanted with a posterior cruciate retaining total knee replacement with a flat polyethylene posterior lipped insert, 12 with a posterior cruciate retaining total knee replacement with a curved insert, and 29 with a posterior cruciate substituting total knee replacement. Each subject performed successive deep knee bends to maximum flexion. Video images at 0 degree, 30 degrees, 60 degrees, and 90 degrees flexion were downloaded onto a workstation computer. Femorotibial contact paths were determined for the medial and lateral condyles using an interactive model fitting technique. Femorotibial contact anterior to the tibial midline in the sagittal plane was denoted as positive and contact posterior was denoted as negative. Analysis of average femorotibial contact pathways of both posterior cruciate retaining designs revealed posterior femorotibial contact in full extension with anterior translation of femorotibial contact commonly observed in midflexion and terminal flexion. In posterior cruciate substituting designs, anterior femoral translation was seen medially at 30 degrees to 60 degrees flexion but rarely was observed laterally. Posterior femoral rollback laterally from full extension to 90 degrees flexion was seen in 100% of subjects implanted with a posterior cruciate substituting total knee replacement, versus 51.6% (posterior lipped polyethylene insert) and 58.3% (curved insert) of those with a posterior cruciate retaining total knee replacement. Data from this multicenter study are remarkably similar to previous fluoroscopy data from a single surgeon series, showing a lack of customary posterior femoral rollback in both posterior cruciate retaining designs, and conversely showing an average anterior femoral translation with knee flexion. Posterior femoral rollback, less than in normal knees, routinely was observed in posterior cruciate substituting total knee arthroplasty, attributed to engagement of the femoral component cam with the tibial post. The abnormal anterior femoral translation observed in posterior cruciate retaining total knee arthroplasty may be a factor in premature polyethylene wear observed in retrieval studies.

Current concepts of total knee arthroplasty

Total knee arthroplasty has become a reliable surgical procedure to treat painful degenerative arthritis. Pain relief and functional improvement is excellent and can allow patients to maintain an active lifestyle. Criteria for the type of prostheses selected should include diagnosis, age, functional level, severity of the disease, and patient expectations. Improved instrumentation, attention to surgical detail, including soft tissue balancing of the knee, and the use of polyethylene inserts greater than 8 mm have led to excellent long-term results and low failure rates. Recent improvements in revision total knee systems should significantly improve the long-term results of revision knee arthroplasty. The addition of modular implants has greatly increased the versatility of most systems and allows the surgeon to custom tailor the implant, contingent upon the amount of bony and ligamentous deficiency of the knee. The future goals of total knee arthroplasty include the development of knee systems that mimic normal joint kinematics with improved fixation and decreased polyethylene wear rates.

The association of non-insulin-dependent diabetes mellitus and cognitive function in an older cohort

OBJECTIVE

In this study, we examined the association of non-insulin-dependent diabetes mellitus (NIDDM) and impaired glucose tolerance (IGT) with cognitive function in a population-based sample of older individuals.

RESEARCH DESIGN AND METHODS

Subjects were 1509 healthy, community-dwelling men and women aged 55 years and older who were participants in the Rancho Bernardo Study and attended clinic visits in 1984-87 and in 1988-91. An oral glucose tolerance test was administered during the 1984-87 visits. Based on World Health Organization criteria, participants were classified into those with NIDDM, IGT, or normal glucose tolerance. During the 1988-91 clinic visits, 12 tests of cognitive function were administered.

RESULTS

Of the participants, 14.3% of the men and 9.9% of the women had NIDDM, and 21.0% of the men and 28.0% of the women had IGT. Multiple regression analysis was used to compare the cognitive function of individuals with NIDDM and IGT with individuals with normal glucose tolerance after adjustment for age, education, obesity, depression, blood pressure, and current estrogen use. In men, there were no statistically significant differences in any of the 12 cognitive function tests by glucose tolerance category. Compared with those with normal glucose tolerance, women with IGT had lower scores on almost every cognitive function test, whereas women with NIDDM had higher scores, but none of these differences were statistically significant after adjustment for multiple comparisons. Furthermore, observed differences by NIDDM or IGT status were small and accounted for < or = 0.6% of the explained variance in cognitive function.

CONCLUSIONS

This study shows no strong or consistent association between IGT or mild diabetes with cognitive function in community-dwelling older adults.

Total knee arthroplasty with the PFC system. Results at a minimum of ten years and survivorship analysis

A consecutive series of 235 total knee arthroplasties using the PFC system was followed prospectively for at least ten years in 186 patients. The operation was for osteoarthritis in 150 knees, for rheumatoid arthritis in 83, and for Paget's disease and femoral osteonecrosis in one knee each. At the latest review 56 patients had died, five were too ill to assess and three could not be traced. The PFC knee replacement utilised was a non-conforming posterior-cruciate-retaining prosthesis with a polyethylene insert which is flat in the sagittal plane. The patella was resurfaced using a metal-backed component in 170 cases, but later in the series we used an all-polyethylene component in 22 knees; 43 patellae were not resurfaced. The survival without need for reoperation for any reason was 90% at ten years. Nineteen revisions were component-related due to failure of nine metal-backed patellae, nine polyethylene inserts, and one unresurfaced patella; two reoperations were for synovectomy (one for recurrent haemarthrosis and one for recurrent rheumatoid synovitis) and three were for metastatic joint infection. There were no revisions for aseptic loosening of femoral or tibial components, or the all-polyethylene patellar replacement. The PFC system provides good and predictable results in tricompartmental arthritis of the knee. Loosening appeared to be negligible, but there were wear-related problems in 8%. The change from a metal-backed patella and an increase in the contact area of the tibial insert should provide further improvement by minimising wear.

Total knee arthroplasty with the PFC system

A consecutive series of 235 total knee arthroplasties using the PFC system was followed prospectively for at least ten years in 186 patients. The operation was for osteoarthritis in 150 knees, for rheumatoid arthritis in 83, and for Paget’s disease and femoral osteonecrosis in one knee each. At the latest review 56 patients had died, fi ve were too ill to assess and three could not be traced.

The PFC knee replacement utilised was a nonconforming posterior-cruciate-retaining prosthesis with a polyethylene insert which is fl at in the sagittal plane. The patella was resurfaced using a metal-backed component in 170 cases, but later in the series we used an all-polyethylene component in 22 knees; 43 patellae were not resurfaced. The survival without need for reoperation for any reason was 90% at ten years. Nineteen revisions were component-related due to failure of nine metal-backed patellae, nine polyethylene inserts, and one unresurfaced patella; two reoperations were for synovectomy (one for recurrent haemarthrosis and one for recurrent rheumatoid synovitis) and three were for metastatic joint infection. There were no revisions for aseptic loosening of femoral or tibial components, or the all-polyethylene patellar replacement.

The PFC system provides good and predictable results in tricompartmental arthritis of the knee. Loosening appeared to be negligible, but there were wear-related problems in 8%. The change from a metal-backed patella and an increase in the contact area of the tibial insert should provide further improvement by minimising wear.

Intraoperative flexion against gravity as an indication of ultimate range of motion in individual cases after total knee arthroplasty

To assess a method of predicting the final postoperative flexion in individual cases after total knee arthroplasty, 364 primary posterior cruciate-retaining total knee arthroplasties were reviewed retrospectively. The knees were subdivided into three preoperative flexion groups--I: poor motion (0 degrees to 85 degrees), II: intermediate motion (90 degrees to 110 degrees), and III: good motion (115 degrees to 140 degrees). There were 302 cases of osteoarthritis and 62 rheumatoid knees (12 juvenile rheumatoid). Correlation was made between preoperative; intraoperative, and postoperative (minimum 2-year follow-up) passive knee flexion for individuals. Intraoperative flexion against gravity was measured after capsular closure by passively flexing the patient's hip 90 degrees and allowing the weight of the lower leg to flex the knee joint. The overall mean value of postoperative flexion for all three groups was similar to preoperative and intraoperative flexion in both osteoarthritis and rheumatoid arthritis. In the poor motion group (I), postoperative flexion (103 degrees) was increased over preoperative flexion (84 degrees) but similar to intraoperative flexion (104 degrees). In the intermediate group (II), postoperative flexion (110 degrees) was similar to both the preoperative flexion (108 degrees) and intraoperative flexion (110 degrees). In the good group (III), postoperative flexion (119 degrees) tended to be less than preoperative flexion (123 degrees) and more than intraoperative flexion (116 degrees), but the differences were not statistically significant. When comparing preoperative and intraoperative flexion to postoperative flexion for individual cases, 55% of knees had postoperative flexion +/-10 degrees of their preoperative value, while 97% of knees had postoperative flexion +/-10 degrees of their intraoperative value. This study indicates that the final postoperative mean flexion for a group of patients with poor preoperative flexion (<85 degrees) and for individual cases (regardless of their preoperative mobility) can best be predicted by intraoperative flexion against gravity rather than by a preoperative value.

Unicompartmental knee arthroplasty in middle-aged patients: a 2- to 6-year follow-up evaluation

Twenty-eight unicompartmental knee arthroplasties performed as an alternative to high tibial osteotomy or tricompartmental knee arthroplasty in patients under 60 years of age were reviewed after 2 to 6 years of follow-up. The patient's age at the time of operation averaged 52 years. Using the Knee Society Score, 90% were rated good or excellent results in terms of function and pain relief. The average flexion angle obtained was 124 degrees, and the average postoperative alignment was 4 degrees of anatomic valgus for varus deformities and 8 degrees for valgus deformities. The average activity level according to the Tegner and Lysholm score slightly improved (preoperative, 2.3; follow-up, 2.7 points). Of the 28 knees, 9 (32%) presented radiolucent lines about the tibial component and two had incomplete radiolucent lines at the bone-cement interface on the femoral side. There was no correlation between activity level and tibial radiolucent lines. Two revisions were performed because of loosening of the femoral component at the prosthesis-cement interface. One was converted to another unicompartmental arthroplasty and the other to a tricompartmental arthroplasty. One tibial component exhibited an asymptomatic slowly progressive radiolucency. Unicompartmental knee arthroplasty in middle-aged patients yields 2- to 6-year results competitive with osteotomy but inferior to tricompartmental arthroplasty in terms of revision. The specific prosthetic design used in this series appeared to be vulnerable to femoral component loosening possibly because of constrained tibial topography and smooth tapered femoral fixation lugs.

Bipolar hemiarthroplasty for primary osteoarthritis of the hip: a review of 41 cases with 8 to 10 years of follow-up

This article reports the results of 41 hips in 36 patients who underwent bipolar hemiarthroplasty for primary osteoarthritis of the hip. Surgical technique included a complete capsulectomy and light reaming of the acetabulum in all patients. The average follow-up was 8.9 years with a minimum of 8 years. Harris hip scores improved from 49 preoperatively to 93 at the latest follow-up, with 95% of the hips rated as excellent or good. Two patients had mild, intermittent groin pain, while a third developed recalcitrant pain necessitating revision. Migration of the bipolar cup was minimal with an average of 2.3 mm superior and 2.1 mm medial migration. Survivorship analysis demonstrated an 89.5% survival rate at 10 years.

Shelf life and in vivo duration. Impacts on performance of tibial bearings

Polyethylene has been used for more than 30 years as an orthopaedic bearing material; however, recently concern has been focused on the early failure of some polyethylene bearings. The damage seen in some bearings has been linked to gamma radiation sterilization performed in an air environment. Gamma sterilization in air has been documented to cause an increase in oxidation and degradation of mechanical properties that continue with time. However, not all retrieved bearings that are gamma sterilized in air exhibit the elevated oxidation and mechanical property degradation that lead to early component failure. Bearings that are gamma sterilized in air oxidize while sitting in inventory before implantation. Shelf oxidation rate was estimated based on analysis of a series of never implanted tibial bearings. This shelf oxidation rate allowed estimation of in vivo oxidation for retrieved tibial bearings of known sterilization date. Bearings with less than 1 year of shelf life after gamma sterilization in air had lower in vivo oxidation and better in vivo performance than did those with longer shelf life before implantation. Shelf time before implantation appears to be a significant factor in the success or failure of bearings that are gamma sterilized in air.

Press-fit condylar total knee arthroplasty. 5- to 9-year follow-up evaluation

Between November 1984 and December 1987, 378 consecutive Press-Fit Condylar (PFC, Johnson & Johnson Professional, Raynham, MA) total knee arthroplasties were performed in 290 patients. The average age at surgery was 67 years (range, 22-91 years). The average follow-up period was 6.5 years (range, 5-9 years). Scoring was carried out according to the Knee Society scoring system. The average preoperative knee score was 28, and the average postoperative knee score was 88. The average preoperative functional knee score was 49, and the average postoperative functional knee score was 72. Ninety-five percent of the patients had no pain on level walking and were satisfied with their functional result. The average postoperative knee flexion was 110 degrees. No implant showed any evidence of radiographic loosening. There were 17 complications, all requiring reoperation. Complications included excessive wear of a metal-backed patella in 8 knees. If complications resulting from the earlier use of a metal-backed patella are eliminated, the overall complication rate is 2.9%, which is comparable to or lower than the rates for other total knee systems with similar follow-up periods.

Sins of omission: what the brochures don't tell you

I have had an opportunity to share with you a few items about surgical technique and instrumentation that are not in most brochures. There are two other instruments that we have not discussed yet that are probably the most important ones to bring into your operating room: your eyes and your brain. Use them wisely and you will have success.

Total hip arthroplasty with cement for juvenile rheumatoid arthritis. Results at a minimum of ten years in patients less than thirty years old

We retrospectively reviewed the clinical and radiographic results of total hip arthroplasty with cement in patients with juvenile rheumatoid arthritis who were less than thirty years old at the time of the index procedure. Thirty-nine patients (sixty-six hips) were managed with this procedure at our institution between 1971 and 1983. Six patients (eleven hips) died before a minimum of ten years of follow-up; the remaining thirty-three patients (fifty-five hips) were followed for at least eleven years. Twenty-eight patients (forty-six hips) had at least one original component in situ after an average duration of clinical follow-up of 15.1 years, and twenty-three of these patients (thirty-eight hips) were followed radiographically for an average of 14.7 years. At the time of the latest follow-up examination, all twenty-eight patients were able to walk outside the home; twenty of these patients (thirty-five hips; 76 per cent) had no pain with activity, and eight patients (eleven hips; 24 per cent) had mild-to-moderate pain with activity. Over-all, twelve (18 per cent) of the sixty-six femoral components and twenty-three (35 per cent) of the sixty-six acetabular components were revised after an average of 12.8 and 11.8 years, respectively. The fifteen-year survival rate for the femoral components was 85 per cent with revision or radiographic loosening as the end point. The fifteen-year survival rate for the acetabular components was 70 per cent with revision as the end point and 61 per cent with revision or radiographic loosening as the end point. The benefits of total hip arthroplasty were maintained over the long term in most of our patients who had juvenile rheumatoid arthritis. However, the durability of the components in these young patients remains a concern.

Conversion of failed modern unicompartmental arthroplasty to total knee arthroplasty

Between January 1983 and January 1991, 29 patients (31 knees) with a failed Robert Brigham metal-backed knee arthroplasty (Johnson & Johnson, Raynham, MA) underwent revision to a total knee arthroplasty (TKA). Twenty-five patients had osteoarthritis, three avascular necrosis, and one rheumatoid arthritis. The average patient age was 72.3 years (range, 49-88 years), and the average weight was 179 lb. (range, 112-242 lb.). The interval between the primary and secondary index procedures averaged 62 months (range, 7-106 months), and mean postrevision follow-up period was 45 months (range, 24-104 months). The primary mechanism of failure of the UKA was tibial polyethylene wear in 21 knees and opposite compartment progression of arthritis in 10 knees. Sixteen knees had particulate synovitis with dense metallic staining of the synovium. At revision, the posterior cruciate ligament was spared in 30 knees and substituted in 1 knee. Restoration of bony deficiency at revision required cancellous bone-graft for contained defects in seven knees, tibial wedges in four knees, and femoral wedges in two knees. No defects received structural allografts. The data suggest that failed, modern unicompartmental knee arthroplasty can successfully be converted to TKA. In most cases, the posterior cruciate ligament can be spared and bone defects corrected with simple wedges or cancellous grafts. Moreover, the results of revision of failed unicompartmental knee arthroplasty are superior to those of failed TKA and failed high tibial osteotomy and comparable to the authors' results of primary TKA with similar-length follow-up periods. Although these results are encouraging, longer-term follow-up evaluation is required to determine survivorship of these revision arthroplasties.

Total knee arthroplasty in a group of patients less than 45 years of age

The long-term follow-up evaluation of total knee arthroplasty (TKA) in patients under age 45 is reviewed. One hundred three knees in 67 patients who had an average follow-up period of 7.2 years were retrospectively reviewed. Fifty-eight percent of the patients had rheumatoid arthritis, and 29% had juvenile rheumatoid arthritis. Thirteen percent of the patients had post-traumatic arthritis, avascular necrosis, hemochromatosis, or lupus. The results demonstrate that the success of TKA in this patient population are comparable to those for TKA in the elderly.

Duplication of medial erosion in unicompartmental knee arthroplasties

Osteoarthritis of the medial compartment of the knee often shows a specific pattern of anterior wear. Review of our revisions from a series of medial metal-backed Brigham unicondylar knee replacements performed between 1983 and 1989 showed that this wear pattern was common on the tibial polyethylene surface. We reviewed these cases retrospectively to compare the pattern of preoperative erosion with the wear of the prosthesis. In all 14 knees with severe anterior wear in a unicompartmental replacement, the prearthroplasty radiographs showed similar patterns, suggesting that the implanted tibial component may continue to be subjected to the same localised stresses that precipitated the failure of the original articular cartilage. Many tibial components implanted during the 1980s had an unacceptably thin anterior rim of polyethylene and it seems that greater thickness is essential at the anterior and peripheral margins of the tibial plateau.

Duplication of medial erosion in unicompartmental knee arthroplasties

Osteoarthritis of the medial compartment of the knee often shows a specific pattern of anterior wear. Review of our revisions from a series of medial metal-backed Brigham unicondylar knee replacements performed between 1983 and 1989 showed that this wear pattern was common on the tibial polyethylene surface. We reviewed these cases retrospectively to compare the pattern of preoperative erosion with the wear of the prosthesis. In all 14 knees with severe anterior wear in a unicompartmental replacement, the prearthroplasty radiographs showed similar patterns, suggesting that the implanted tibial component may continue to be subjected to the same localised stresses that precipitated the failure of the original articular cartilage. Many tibial components implanted during the 1980s had an unacceptably thin anterior rim of polyethylene and it seems that greater thickness is essential at the anterior and peripheral margins of the tibial plateau.

Popliteus tendon dysfunction following total knee arthroplasty

The popliteus tendon can be a potential source of internal derangement after total knee arthroplasty. It can subluxate anteriorly and posteriorly over a retained lateral femoral condylar osteophyte or over the overhanging edge of the metallic posterior femoral condyle. Surgical release of the tendon from its femoral insertion relieves the problem.