Twenty-Five-Years and Greater, Results After Nonmodular Cemented Total Knee Arthroplasty.

BACKGROUND: Total knee arthroplasty (TKA) has been shown to be very successful with long-term follow-ups. But there are no reports showing prosthesis survival at 25-30 years. Here, we report the outcomes for 25-30 years using the Anatomic Graduated Component (Biomet, Warsaw, IN) TKA and elucidate the etiology and cause of failure of the components. METHODS: We reviewed the outcomes of 5649 primary total knee arthroplasties for 25-30 years using the Anatomic Graduated Component. Statistical analysis was performed by the Kaplan-Meier survival analysis. Clinical outcomes included the Knee Society Score and standardized radiographs to check for loosening of the implants. The reason for revision surgery was reviewed retrospectively. We compared our results with those at another institution with similar long-term follow-up. RESULTS: There were 112 failures, 48 with aseptic loosening and 25 with instability for an overall prosthesis survival rate of 94.2% at 25 years and 92.4% at 30 years follow-up. In the third decade after TKA, patients are substantially more likely to experience death than experience a failing prosthesis, with a 3811% greater risk of dying relative to failing (Risk ratio = 38.1, Odds ratio = 56.7, P < .0001). CONCLUSION: There was a greater risk of dying than failing over time. The primary reason for revision knee surgery was due to aseptic loosening of the prosthesis followed by instability.

Ten-Year Outcome Comparison of the Anatomical Graduated Component and Vanguard Total Knee Arthroplasty Systems.

UNLABELLED: The development of a new total knee system as a successor prosthesis in total knee arthroplasty (TKA) requires clinical outcome improvement. 10,843 TKAs were performed of which 9169 utilized the Anatomical Graduated Component (AGC) and 1674 utilized the Vanguard prosthesis (both Biomet, Warsaw, IN). Survival rates at ten years postoperatively for the AGC and Vanguard were 98.7% and 98.4% (P=.4897) respectively. The top reasons for component failure were loosening (AGC: 0.29%, Vanguard: 0.30%), polyethylene wear, and instability (AGC: 0.13%, Vanguard: 0.12%). These results reveal similar outcomes in both designs, with relatively few revisions and high survival rates at ten years postoperatively. SUMMARY: This abstract offers data concerning the usefulness of the Vanguard Total Knee System as a successor to the Anatomical Graduated Component.

Use of screws and cement in revision TKA with primary or revision specific prosthesis with up to 17 years followup.

The purpose of this study was to investigate the use for screws and cement, and primary and revision specific prosthesis for revision TKA. Between July 1989 and February 2010, 839 consecutive revision TKAs were performed, with 609 knees meeting inclusion criteria. At 17 years followup, Kaplan-Meier survivorship was 0.9859 for revision specific prosthesis with screws and cement, 0.9848 for revision prosthesis with no screws, 0.9118 for primary prosthesis with screws, and 0.9424 for primary prosthesis with no screws. Revision TKAs using screws had greater defects (P<.0001). Use of revision prosthesis along with screws and cement to correct largely defective revision TKAs is highly recommended.

Use of screws and cement in primary TKA with up to 20 years follow-up.

The purpose of this study was to investigate screws and cement for large tibial bone defects during primary TKA. Of 14,686 consecutive primary TKAs performed between December 1988 and February 2010, 256 received screws and cement for tibial defects. Cox regression was used for the analysis. 20-year survival probability was 0.9897 (screws) and 0.9339 (no screws) (P = .4225 log-rank). Tibial bone condition was significantly worse in knees receiving screws (P < .0001) with 73.0% having defects in the screws group and 3.4% (P < .0001) for non-screws. Radiolucency appeared in 13.7% (screws) and 6.4% (no screws) postoperatively. Screws were $137 each, wedges $910 to $2240. Knees with tibial defects and screws performed similarly if not better than knees without defects at substantially lower cost than alternatives.

Acetabular UHMWPE survival and wear changes with different manufacturing techniques.

BACKGROUND: Polyethylene wear may be affected by the type of polyethylene resin, manufacturing technique, degree of thermal stabilization, and sterilization technique. QUESTIONS/PURPOSES: We therefore compared femoral head penetration into the PE and cup survival using the same cup system with different PE resins, manufacturing, and sterilization techniques. METHODS: Our study group consisted of 1912 THAs performed using the same uncemented cup and identical 28-mm cobalt-chrome heads. The polyethylene varied as follows: Group 1 (94 cups), GUR 4150 resin, ram-extruded, sterilized in air, no barrier packaging; Group 2 (74 cups), same as Group 1 but sterilized in argon; Group 3 (75 cups), Himont 1900 resin, compression-molded bar stock, sterilized in argon, no barrier packaging; Group 4 (620 cups), same as Group 3 except with barrier packing; Group 5 (711 cups), GUR 1050 resin, compression-molded bar stock, sterilized in argon gas with barrier packaging; and Group 6 (338 cups), GUR 1050 resin, compression-molded bar stock, sterilized in argon with barrier packaging, irradiated with 50 kGy, heated below melting temperature, machined, and finally placed in nonbarrier packaging with gas plasma sterilization. Minimum followup was 2 years (average, 7 years; range, 2-17 years). RESULTS: Femoral head penetration averaged 0.05 mm per year for Groups 5 and 6 and was substantially lower than for Groups 1 to 4. Cup survival was higher at seven years in Groups 3, 4, and 5, and at 10 years in group 4 when compared to groups 1, 2, and 3. CONCLUSIONS: We observed lower FHP rates and higher cup survival with polyethylene machined from direct compression-molded bar stock, sterilized in argon gas, with barrier packaging. LEVEL OF EVIDENCE: Level III Therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Coronal alignment in total knee arthroplasty: just how important is it?

A recent study has challenged the premise that well-aligned total knee arthroplasties (TKAs) have better survival than outliers. This study examines the importance of overall coronal alignment as a predictor for revision. Patients with primary TKAs were stratified into neutral, varus, and valgus alignment groups based on the postoperative tibiofemoral angle. In 6070 knees (3992 patients), there were 51 failures (0.84%): 21 (0.5%) in the neutral group, 18 (1.8%) in the varus group, and 12 (1.5%) in the valgus group. The best survival was for overall alignment between 2.4 degrees and 7.2 degrees of valgus. Varus knees failed primarily by medial tibia collapse, whereas valgus knees failed from ligament instability. Outliers in overall alignment have a higher rate of revision than well-aligned knees. The goal of TKA should be to restore alignment within 2.4 degrees to 7.2 degrees of valgus.

Morbidly obese, diabetic, younger, and unilateral joint arthroplasty patients have elevated total joint arthroplasty infection rates.

The study aims to delineate the deep infection rates and infection risk factors for primary total knee and total hip arthroplasty patients. A retrospective review was conducted on 6108 patients from 1991 to 2004. The deep infection cases were compared to the noninfected cohort whereby infection risk factors were identified. Of the 8494 joint arthroplasties, 43 (0.51%) developed a deep infection (30 total knee arthroplasties, 13 total hip arthroplasties). Patients with a body mass index greater than 50 had an increased odds ratio of infection of 21.3 (P < .0001). Diabetic patients were 3 times as likely to become infected compared to nondiabetic patients (P = .0027). Simultaneous bilateral total joint arthroplasties were found to have developed infection 3 times less frequently than those performed as unilateral procedures (P = .0024). The average age in our infection cohort was 64.3 and 68.4 in the noninfected cohort. In this retrospective review study, obesity, diabetes, and younger age were found to be risk factors for joint arthroplasty infection.

The effect of stuffing the patellofemoral compartment on the outcome of total knee arthroplasty.

BACKGROUND: The effect of so-called stuffing of the patellofemoral compartment at the time of total knee arthroplasty (that is, increasing the anterior patellar displacement, the anteroposterior femoral size, or the combined anteroposterior patellofemoral size) has not been well studied. The purpose of the present study was to evaluate the effect of stuffing the patellofemoral compartment on the outcome of primary total knee arthroplasty. METHODS: A retrospective review of 1100 primary total knee arthroplasties that had been performed in 1997 and 1998 was conducted. Eight hundred and thirty arthroplasties (75.5%) met the diagnostic and minimum two-year follow-up criteria for inclusion in this report. Radiographic measurements were made to determine preoperative and postoperative anterior patellar displacement, anteroposterior femoral size, combined anteroposterior patellofemoral size, anterior femoral offset, and posterior femoral offset. Regression analysis was performed to determine the effects of changes in these variables on the range of motion, the Knee Society Knee Score, the Knee Society Function Score, the Knee Society Pain Score, and the rate of lateral retinacular release. RESULTS: Preoperative to postoperative changes in anterior patellar displacement, anteroposterior femoral size, combined anteroposterior patellofemoral size, anterior femoral offset, and posterior femoral offset had no clinically meaningful effect on the range of motion of the knee or on any of the Knee Society scores. Increases in anterior patellar displacement were associated with a lower probability of the need for a lateral retinacular release. Increases in measured anteroposterior femoral size were associated with a higher probability of the need for lateral release. Even when combined, however, these relationships explained only 10.1% of the observed variance in the need for lateral retinacular release. Moreover, analyses indicated that patient gender, large as opposed to medium patellar size, and absolute femoral component size influenced the likelihood of lateral release more than did anterior patellar displacement and measured anteroposterior femoral size. CONCLUSIONS: Our findings do not support the widely held belief that stuffing of the patellofemoral joint results in adverse outcomes after total knee arthroplasty. Furthermore, the need for lateral release appears to be multifactorial and likely involves a more complex set of factors. Thus, without evidence of other identifiable causes of failure, we do not recommend revision for the treatment of pain of an overstuffed knee joint.

Total knee arthroplasty effectiveness in patients 55 years old and younger: osteoarthritis vs. rheumatoid arthritis.

In the past, total knee arthroplasty, although very successful, was only indicated for an elderly population. Recently though, several papers have been published confirming that total knee arthroplasty is effective in younger patients. This paper supports the results of those papers. In our study, 207 total knee arthroplasties were performed on patients 55 years old and younger using a posterior cruciate-retaining prosthesis. There was an overall survival rate of 97.6% with an average follow-up of 9.1 years. There were some minor variations in the outcome of the operation based on diagnosis (osteoarthritis vs. rheumatoid arthritis). The success also continued over time with an estimated survival rate of 94.8% at 12 years. Total knee arthroplasty is an effective operation in patients younger then 55 years old.

Seasonal variation in adult hip disease secondary to osteoarthritis and developmental dysplasia of the hip.

AIM: To determine if there was a seasonal variation in adults undergoing total hip arthroplasty for end stage hip disease due to osteoarthritis (OA) or sequelae of developmental dysplasia of the hip (DDH). METHODS: The total hip registry from the author's institution for the years 1969 to 2013 was reviewed. The month of birth, age, gender, and ethnicity was recorded. Differences between number of births observed and expected in the winter months (October through February) and non-winter mo (March through September) were analyzed with the χ2 test. Detailed temporal variation was mathematically assessed using cosinor analysis. RESULTS: There were 7792 OA patients and 60 DDH patients who underwent total hip arthroplasty. There were more births than expected in the winter months for both the DDH (P < 0.0001) and OA (P = 0.0052) groups. Cosinor analyses demonstrated a peak date of birth on 1st October. CONCLUSION: These data demonstrate an increased prevalence of DDH and OA in those patients born in winter.

Cemented and uncemented total hip arthroplasty using the same femoral component.

PURPOSE: The purpose of this study was to evaluate the same femoral component after cemented and uncemented total hip arthroplasty. The results were compared in terms of hip scores, subsidence, and survivorship. METHODS: Between 1986 and 1996, 1017 primary THAs were implanted in 882 patients using the same porous-coated, titanium-alloy, femoral component. 507 cemented stems (441 patients) and 510 uncemented stems (441 patients) were compared. The primary diagnosis was osteoarthritis in 866 hips (85%). 541 patients were female (61%). The clinical results were evaluated based on the Harris hip score. Radiographs were evaluated at each follow-up for stem subsidence and loosening. Kaplan-Meier survival analysis was used to determine stem survivorship. The average follow-up of the entire cohort was 13.2 years (range, 2-26 y). RESULTS: The average Harris Hip Scores at 20 years follow-up was 87 points in the cemented group and 85 points in the uncemented group. Pain scores averaged 42 and 38 in the cemented and uncemented group, respectively, at 20 years. There were 6 loose stems identified in the cemented group (1.2%) and 2 loose stems in the uncemented group (0.4%). Cemented and uncemented stem survivorship at 20 years was 98.1% and 99.6%, respectively. There was no difference in cemented or uncemented stem survivorship at any time period. CONCLUSIONS: Although there were more cases of aseptic cemented femoral component loosening, there was no significant difference in stem survivorship out to 20 years whether this stem was implanted with or without cement.

Clinical predictors for possible failure after total hip arthroplasty.

INTRODUCTION: With the rising number of total hip arthroplasties (THAs) each year, it is increasingly important for surgeons to have evidence-based information on which to determine how often patients should be examined postoperatively. The purpose of this research was to determine whether it is possible to identify - based on Harris Hip Score (HHS) - early signs or predictors of THA failure so that methods of postoperative follow-up can be scheduled in advance of the time frame indicated by those predictors of failure. METHODS: The HHS of 9,949 primary THAs performed from 1973 to 2012 was reviewed retrospectively to identify the clinical predictors of failure. 1,131 hips were completely lost to follow-up, leaving 8,331 primary THAs in 6,979 patients. Time to failure was recorded with Kaplan-Meier analysis performed with aseptic loosening or revision of any component as the endpoint. RESULTS: Regression analysis revealed that a pain score of 30 or less at any time of follow-up (p<0.0001) was a significant risk and strongly indicative of later failing. A low distance walked score of 5 or less at 6 months (p = 0.0087) and 1 year (p = 0.0167) served as an early predictor of future failure. A lower stairs score of 2 or less was also an early predictor at 1 year (p = 0.0343) and at 3 years (p = 0.0245). A lower limp score of 8 or less was a mid-term predictor at 3 (p = 0.0001), 5 (p = 0.0002), 7 (p = 0.0191) and 10 (0.0028) years postoperative follow-up. CONCLUSIONS: Pain, walk, stairs and limp scores are predictive of THA failure. Surgeons with patients who present with these indicators should optimise postoperative follow-ups to alert their patients.

ACL Damage and Deficiency is Associated with More Severe Preoperative Deformity, Lower Range of Motion at the Time of TKA.

BACKGROUND: ACL status varies in the arthritic knee during TKA. QUESTIONS/PURPOSES: The purpose of this study was to examine clinical features and intraoperative findings associated with stages of ACL degeneration. METHODS: Coronal deformity, ROM, intra-articular degenerative patterns, and ligament releases were assessed for 1656 knees during TKA. Common patterns of deformity and severity of degenerative change were assessed as a function of the severity of ACL deficiency. RESULTS: Of the 1656 knees assessed, 27% had a normal ACL, 55% exhibited damage, and 18% exhibited complete absence of the ACL. Increased coronal deformity and lower preoperative ROM was associated with ACL deficiency. Increased chondral and meniscal damage and more extensive osteophyte formation were also found. More extensive ligament releases were required in ACL-deficient knees. CONCLUSIONS: The status of the ACL is predictive of the need for increased surgical deformity correction. A better understanding of ACL status is an important consideration during in choosing TKA as opposed to unicompartmental arthroplasty. The status of the ACL should be considered in planning for implant choice in TKA.

The effect of femoral notching during total knee arthroplasty on the prevalence of postoperative femoral fractures and on clinical outcome.

BACKGROUND: The treatment of a supracondylar femoral fracture following total knee arthroplasty is complicated by the presence of the prosthetic components. Anterior femoral notching during arthroplasty has been implicated as a contributing risk factor for femoral fracture. We retrospectively reviewed the effect of anterior femoral notching on the subsequent occurrence of a periprosthetic supracondylar fracture of the distal aspect of the femur and the outcomes of primary total knee arthroplasty in such patients. METHODS: The prevalence and depth of femoral notching were determined on a review of the lateral radiographs by observers blinded to the clinical results of 1089 consecutive total knee replacements performed in 1997 and 1998. Linear and logistic regression modeling was used to analyze the relationship between femoral notching and the prevalence of supracondylar femoral fracture, postoperative range of motion, the Knee Society score, and the Knee Society functional and pain scores. RESULTS: Femoral notching was performed in 325 (29.8%) of the 1089 knees in our series. During an average follow-up period of 5.1 years, only two supracondylar femoral fractures occurred, both in femora treated without notching. Femoral notching was not associated with an increased rate of fracture (p = 1.000) or with significant differences in the measures of outcome (range of motion [p = 0.117], knee score [p = 0.967], functional score [p = 0.861], need for a lateral release [p = 0.234], or postoperative pain [p = 0.948]). CONCLUSIONS: This study demonstrated no difference in knees managed with or without notching of the anterior distal aspect of the femur with respect to the occurrence of a supracondylar fracture, range of motion, Knee Society score, Knee Society function, or pain.

Predicting range of motion after total knee arthroplasty. Clustering, log-linear regression, and regression tree analysis.

BACKGROUND: Range of motion is a crucial measure of the outcome of total knee arthroplasty. The purpose of this study was to determine which factors are predictive of the postoperative range of motion. METHODS: We retrospectively studied 3066 patients (4727 knees) who had a primary total knee arthroplasty with the same type of implant at the same center between 1983 and 1998. Statistical clustering analysis paired with log-linear regression was used to determine groupings along continuous variables. Regression tree analysis was used to characterize the combinations of variables influencing the postoperative range of motion. The variables considered were preoperative and intraoperative flexion and extension, preoperative alignment, age, gender, and soft-tissue releases. RESULTS: Preoperative flexion was the strongest predictor of the postoperative flexion regardless of preoperative alignment. Other factors that were significantly related to reduced flexion were intraoperative flexion (p < 0.0001), gender (p < 0.0001), preoperative tibiofemoral alignment (p = 0.0005), age (p < 0.0001), and posterior capsular release (p < 0.0001). The removal of posterior osteophytes was related to the greatest increase in postoperative flexion in the group of patients with a varus tibiofemoral alignment preoperatively. CONCLUSIONS: The principal predictive factor of the postoperative range of motion was the preoperative range of motion. Removal of posterior osteophytes and release of the deep medial collateral ligament, the semimembranosus tendon, and the pes anserinus tendon in patients with large preoperative varus alignment and the attainment of a good intraoperative range of motion improved the likelihood that a good postoperative range of motion would be achieved.

Simultaneous bilateral, staged bilateral, and unilateral total knee arthroplasty. A survival analysis.

BACKGROUND: The rates of perioperative morbidity and mortality are areas of concern associated with simultaneous bilateral total knee replacement. The purpose of this paper was to compare the rates of morbidity and mortality and the clinical outcome in large groups of consecutive patients undergoing simultaneous bilateral total knee replacement, unilateral total knee replacement, or staged bilateral total knee replacement. METHODS: A total of 6200 total knee replacements, performed in 3998 patients between 1983 and 2000, consisted of 2050 simultaneous bilateral, 1796 unilateral, and 152 staged bilateral total knee replacements. A review of each group was conducted to compare the rates of morbidity and mortality, the survival of the prosthesis, and the clinical outcome. Kaplan-Meier survival analyses were performed with failure defined as revision because of aseptic loosening and as patient death. Complications and Knee Society scores were compared throughout the fifteen-year follow-up period (average, 4.3 years of follow-up). RESULTS: The unilateral group had significantly lower Knee Society scores than the simultaneous bilateral group (p < 0.0001 up to twelve years, and p = 0.0067 at fifteen years) across all postoperative time-intervals. The percentage of patients who had thrombophlebitis was significantly higher in the simultaneous bilateral group (0.9%) than in the unilateral group (0.3%) (p = 0.0326). No significant differences were found with regard to prosthetic failure, cardiac complications, and the rates of death in the three groups. Ten years postoperatively, the simultaneous bilateral group had a significantly higher rate of patient survival than did the unilateral group (78.6% compared with 72.0%) (p = 0.0062). CONCLUSIONS: The significantly higher rate of thrombophlebitis in the simultaneous bilateral group compared with that in the unilateral group may represent a greater risk to those patients. However, we believe that when there are adequate indications for bilateral total knee replacement, simultaneous bilateral arthroplasty is beneficial to patients, with a minimal increase in the risk of death or other complications compared with that associated with unilateral and staged procedures.

The Surgeon's Role in Relative Success of PCL-Retaining and PCL-Substituting Total Knee Arthroplasty.

BACKGROUND: The orthopedic literature has not shown a universal and replicated difference, outside of flexion, in clinical results between posterior cruciate ligament retention and posterior cruciate ligament substitution in total knee arthroplasty. QUESTIONS/PURPOSES: This study was performed to compare the restoration of flexion and knee function in a large series of cruciate-retaining and cruciate-substituting total knee arthroplasties (TKRs). In addition, we aimed to study how other variables, such as those unique to each surgeon, may have affected the results. PATIENTS AND METHODS: The current study evaluated 8,607 total knee arthroplasties in 5,594 patients performed by six surgeons, each using one of four prosthesis designs (two posterior cruciate ligament retaining, two posterior cruciate ligament substituting). Knees were compared at the level of cruciate-retaining and cruciate-substituting knees, at the level of the four prostheses, and at the level of surgeon-implant combinations. Least squared means scores were obtained through multiple linear regression, analysis of variance, and the maximum likelihood method. RESULTS: At the level of posterior cruciate ligament treatment, posterior cruciate ligament substitution as a whole showed 3.2° greater flexion than posterior cruciate ligament retention. At the prosthesis level, cruciate-substituting models provided greater flexion and cruciate-retaining models provided higher function scores. In the surgeon-implant combinations, surgeons provided mixed results that often did not reflect findings from other levels; one surgeon's use of a posterior cruciate ligament retaining prosthesis achieved 14.7° greater flexion than the surgeon's use of a corresponding posterior cruciate ligament substituting design. CONCLUSIONS: Posterior cruciate ligament treatment is confounded by other variables, including the operating surgeon. The arthroplasty surgeon should choose a prosthesis based, not only on outside results, but also on personal experience and comfort.

Preoperative malalignment increases risk of failure after total knee arthroplasty.

BACKGROUND: Implant survival after total knee arthroplasty has historically been dependent on postoperative knee alignment, although failure may occur when alignment is correct. Preoperative knee alignment has not been thoroughly evaluated as a possible risk factor for implant failure after arthroplasty. The purpose of this study was to analyze the effect of preoperative knee alignment on implant survival after total knee arthroplasty. METHODS: We performed a retrospective review of 5342 total knee arthroplasties performed with use of cemented Anatomic Graduated Component implants from 1983 to 2006. Each knee was independently measured preoperatively and postoperatively for overall coronal alignment. Neutral ranges for preoperative and postoperative alignment were defined by means of Cox proportional hazards regression. RESULTS: The overall failure rate was 1.0% (fifty-four of 5342 prostheses); failure was defined as aseptic loosening of the femoral and/or tibial component. The average preoperative anatomical alignment (and standard deviation) was 0.1° ± 7.7° of varus (range, 25° of varus to 35° of valgus), and the average postoperative anatomical alignment (and standard deviation) was 4.7° ± 2.5° of valgus (range, 12° of varus to 20° of valgus). The failure rate in knees in >8° of varus preoperatively (2.2%; p = 0.0005) or >11° of valgus preoperatively (2.4%; p = 0.0081) was elevated when compared with knees in neutral preoperatively (0.71%). Knees with preoperative deformities corrected to postoperative neutral alignment (2.5° through 7.4°) had a lower failure rate (1.9%) than undercorrected or overcorrected knees (3.0%) (p = 0.0103). Knees with postoperative neutral alignment, regardless of preoperative alignment, had a lower failure rate (0.74%) than knees with postoperative alignment of <2.5° or >7.4° of anatomic valgus (1.7%) (p < 0.0001). CONCLUSIONS: Patients with excessive preoperative alignment (>8° of varus or >11° of valgus) have a greater risk of failure (2.3%). Neutral postoperative alignment (2.5° through 7.4° of valgus) improves (1.9% for preoperatively deformed knees) but does not completely eliminate the risk of failure (0.5% for knees that were neutral both preoperatively and postoperatively). Careful attention should be paid to knee alignment during total knee arthroplasty, especially for patients with severe preoperative deformities.

The effect of alignment and BMI on failure of total knee replacement.

BACKGROUND: The purpose of this study was to determine the effect of tibiofemoral alignment, femoral and tibial component alignment, and body-mass index (BMI) on implant survival following total knee replacement. METHODS: We retrospectively reviewed 6070 knees in 3992 patients with a minimum of two years of follow-up. Each knee was classified on the basis of postoperative alignment (overall tibiofemoral alignment and alignment of the tibial and the femoral component in the coronal plane). Failures (defined as revision for any reason other than infection) were analyzed with use of Cox regression; patient covariates included overall alignment, component alignments, and preoperative BMI. RESULTS: Failure was most likely to occur if the orientation of the tibial component was <90° relative to the tibial axis and the orientation of the femoral component was ≥8° of valgus (failure rate, 8.7%; p < 0.0001). In contrast, failure was least likely to occur if both the tibial and the femoral component were in a neutral orientation (≥90° and <8° of valgus, respectively) (failure rate, 0.2% [nine of 4633]; p < 0.0001). "Correction" of varus or valgus malalignment of the first implanted component by placement of the second component to attain neutral tibiofemoral alignment was associated with a failure rate of 3.2% (p = 0.4922) for varus tibial malalignment and 7.8% (p = 0.0082) for valgus femoral malalignment. A higher BMI was associated with an increased failure rate. Compared with patients with a BMI of 23 to 26 kg/m2, the failure rate in patients with a BMI of ≥41 kg/m2 increased from 0.7% to 2.6% (p = 0.0046) in well-aligned knees, from 1.6% to 2.9% (p = 0.0180) in varus knees, and from 1.0% to 7.1% (p = 0.0260) in valgus knees. CONCLUSIONS: Attaining neutrality in all three alignments is important in maximizing total knee implant survival. Substantial "correction" of the alignment of one component in order to compensate for malalignment of the other component and thus produce a neutrally aligned total knee replacement can increase the risk of failure (p = 0.0082). The use of conventional guides to align a total knee replacement provides acceptable alignment; however, the surgeon should be aware that the patient's size, as determined by the BMI, is also a major factor in total knee replacement failure.

The effect of an anterior cervical operation for cervical radiculopathy or myelopathy on associated headaches.

BACKGROUND: Headaches related to the cervical spine have been reported by various authors, and modalities of treatment are as varied as their speculated causes. The purpose of this study was to determine if anterior cervical reconstructive surgery (cervical arthrodesis and disc arthroplasty) for the treatment of radiculopathy or myelopathy also helps to alleviate associated headaches. METHODS: We conducted a post hoc analysis of study cohorts combined from prospective studies comparing the results of Prestige and Bryan cervical arthroplasty devices and those of anterior cervical arthrodesis with allograft and anterior instrumentation. A total of 1004 patients (51.6% were male) were evaluated with use of the Neck Disability Index questionnaire preoperatively and at five points postoperatively, with the latest evaluation at twenty-four months, resulting in a follow-up of 803 patients. RESULTS: At the twenty-four-month follow-up, the improvement from baseline with regard to headache was significant in both groups (p < 0.0001), with patients who underwent arthroplasty reporting numerically better pain scores. Most arthroplasty and arthrodesis patients (64% and 58.5%, respectively) had improvement in the pain score of at least one grade. Conversely, the pain scores for 8.4% of those who had an arthroplasty and 13.7% of those who had arthrodesis worsened by at least one grade. For the remainder, the score was unchanged. Overall, the patients who had an arthroplasty had significant improvement more frequently than did the patients who had arthrodesis (p = 0.011). CONCLUSIONS: At two years postoperatively, patients undergoing anterior cervical operations, both those who have an arthroplasty and those who have an arthrodesis, for cervical radiculopathy and myelopathy can be expected to have significant improvement from baseline with regard to headache symptoms.