Cemented femoral stem fixation through the anterior approach has fewer early complications than cementless fixation.

AIMS: To achieve the functional benefits of the direct anterior (DA) approach and the fixation benefits of cemented replacement, this study combined the two techniques posing the following questions: does the limited access of the DA approach adversely affect the cement technique?; and does such a cementing technique reduce the incidence of cementless complications? METHODS: A consecutive series of 341 patients (360 hips) receiving the DA approach between 2016 and 2018 were reviewed. There were 203 cementless stems and 157 cemented stems. Mean age was 75 years (70 to 86) in the cementless group and 76 years (52 to 94) in the cemented group, with 239 (70%) females in the whole series. Femoral complications were compared between the two groups. Mean follow-up was 1.5 years (0.1 to 4.4) for patients in the cementless group and 1.3 years (0.0 to 3.9) for patients in the cemented group. RESULTS: The cementless group had a higher rate of femoral complications (8 vs 0; p = 0.011). There were two loose stems and six fractures, all requiring revision. Fractures occurred a mean 14.5 days (2 to 31) postoperatively and loosening at 189 days and 422 days postoperatively. Femoral cementing can be done using the DA approach safely and reduces the number of complications compared with a contemporary cementless series. CONCLUSION: A higher rate of early fractures and loosening occurred with cementless stems. This was not observed in our cemented stem cohort and cementing was safely accomplished through the DA approach. The modern femoral cementing process with the DA approach does not add to surgical complexity or time, has fewer early complications, and is a safer option for older patients compared to cementless femoral arthroplasties. Cite this article: Bone Joint J 2021;103-B(7 Supple B):33-37.

The AAHKS Clinical Research Award: No Evidence for Superior Patient-Reported Outcome Scores After Total Hip Arthroplasty With the Direct Anterior Approach at 1.5 Months Postoperatively, and Through a 5-Year Follow-Up.

BACKGROUND: The direct anterior approach to total hip arthroplasty (THA) may result in superior early postoperative patient-reported outcome measures (PROMs). This study compared PROMs between THA patients treated with the direct anterior or posterolateral approach between 1.5 months and 5 years, using literature-derived patient acceptable symptom state (PASS) and minimal clinically important improvement (MCII) thresholds. METHODS: A propensity score match of 93 direct anterior patients to 93 posterolateral patients from a multicenter US collaboration (6 centers, 398 patients) was performed. The Harris Hip Score (HHS), the Short-Form 36, and a Numerical Rating Scale for Pain were collected preoperatively, postoperatively (mean days: 47), and at 1, 3, and 5 years. The proportion of patients reaching the HHS PASS, Pain MCII, and Function MCII in the direct anterior and posterolateral groups was compared using binary logistic regressions, controlling for age, gender, body mass index, and Charnley score. RESULTS: Direct anterior patients were less likely to reach the HHS PASS at the postoperative visit (P = .015; odds ratio = 0.454), but not at later visits (P > .082). Direct anterior patients had no difference from posterolateral patients in their tendency to reach the Pain MCII postoperatively or at 1 year (P > .090). The direct anterior patients were less likely to reach the Function MCII at the postoperative visit (P = .011; odds ratio = 0.422), but not at 1 year (P = .958). CONCLUSION: No evidence was found of superior early postoperative PROM scores in THA patients treated with the direct anterior approach. No PROM differences were found at or beyond 1 year, indicating that patients reach similar final symptom states, regardless of surgical approach.

Modern Day Bicruciate-Retaining Total Knee Arthroplasty: A Short-Term Review of 146 Knees.

BACKGROUND: Bicruciate retaining (BCR) implants were first proposed in the 1960s with the polycentric knee. Given the technical difficulty of implanting these devices, and the mixed results at the time, the BCR concept had stalled, until recently. This study seeks to provide a short-term review of the BCR implant design, describe patient-reported outcomes, and discuss key aspects to ensure successful implantation of the modern-day BCR implant design. METHODS: Between October 2014 and December 2016, the senior author performed 146 primary total knee arthroplasties using BCR implants. Arthritic knees, with minimal soft tissue damage and an intact anterior cruciate ligament, were the general indications used for this cohort. All patients implanted with the BCR device were included in this analysis. One hundred forty-six (100%) BCR knees were available for follow-up at an average of 12 months (range, 1-33 months) postoperatively. RESULTS: Ninety-one percent of respondents reported their knee always or sometime feels normal, with only 9% of respondents reporting their knee never feels normal. Our study reports 94% of patients reported neutral satisfaction or higher, with only 6% of patients reporting dissatisfaction and 1% reported being very dissatisfied. Of all 146 BCR devices implanted, there were 2 (1.4%) revisions and 1 (0.7%) reoperation, a manipulation under anesthesia. CONCLUSION: This is the largest consecutive series of BCR total knee arthroplasties using the modern-day implant design with 1-year follow-up in the United States. The results of our study show great patient-reported satisfaction, function, and short-term outcomes for patients implanted with the new BCR design.

Eight Hundred Twenty-Five Medial Mobile-Bearing Unicompartmental Knee Arthroplasties: The First 10-Year US Multi-Center Survival Analysis.

BACKGROUND: FDA approval for the Oxford phase III device was approved for use in the United States in 2004. This study seeks to provide the first long-term, large patient sample size, Oxford phase III multi-site survivorship study in the United States, investigating patient reported outcomes of pain and function, while also providing an in-depth analysis of causes for revision, and finally addressing recent advancements that can help aid the unicompartmental knee arthroplasty (UKA) process and further improve partial knee survivorship. METHODS: Between July 2004 and December 2006, 5 surgeons from around the United States performed medial UKA through the minimally invasive surgical approach, on 825 knees in 695 patients. This was a consecutive series of primary UKAs using the phase III mobile bearing; cemented Oxford Knee (Zimmer Biomet, Warsaw, IN), implanted utilizing phase III instrumentation. UKA survivorship considered all revisions as the end point. Implant survivorship eliminated revisions at which the original Oxford implant was determined to be well fixated and functional intra-operatively. RESULTS: A total of 93 knees were revised in this study. Mean follow-up was 9.7 years (6-12). Implant survivorship at year 10 was 90% (confidence interval 2.7%). UKA survivorship at year 10 was 85% (confidence interval 3.8%). Average preoperative American Knee Society Score (knee score) was 49 and rose to 90 postoperatively (standard deviations 16 and 18, respectively). Average preoperative American Knee Society Score (function score) was 55 and rose to 77 postoperatively (standard deviations 15 and 28, respectively). CONCLUSION: This was the first large-scale, 10-year, multi-site follow-up of the Oxford mobile-bearing medial UKA undertaken in the United States, displaying good survivorship and excellent patient outcomes.

No Difference in Early Analgesia Between Liposomal Bupivacaine Injection and Intrathecal Morphine After TKA.

BACKGROUND: Opioid analgesics have been a standard modality for postoperative pain management after total knee arthroplasty (TKA) but are also associated with increased risk of nausea, pruritus, vomiting, respiratory depression, prolonged ileus, and cognitive dysfunction. There is still a need for a method of anesthesia that can deliver effective long-term postoperative pain relief without incurring the high cost and health burden of opioids and nerve blocks. QUESTIONS/PURPOSES: (1) Is liposomal bupivacaine-based periarticular injection (PAI) more effective than morphine-based spinal anesthesia or ropivacaine-based PAI in controlling postoperative pain after TKA? (2) Do patients treated with liposomal bupivacaine-based PAI experience fewer opioid-related adverse events compared with patients treated with morphine-based spinal anesthesia or ropivacaine-based PAI in controlling postoperative pain after TKA? METHODS: This multicenter, blind trial randomized 119 patients undergoing TKA with spinal anesthesia to receive spinal anesthesia plus periarticular injection with liposomal bupivacaine (40 patients), spinal anesthesia with bupivacaine plus intrathecal morphine (41 patients) but no liposomal bupivacaine injection, or spinal anesthesia with bupivacaine (38 patients) and no liposomal bupivacaine injection. The two groups that did not receive periarticular liposomal bupivacaine did receive periarticular injection with ropivacaine, and all three groups had ketorolac (30 mg) plus epinephrine (1:1000) in the periarticular injections. Patients in all three groups received identical perioperative multimodal analgesic and antiemetic drugs. All patients were analyzed in the group to which they were randomized and no patients were lost to followup. The primary study endpoints were visual analog score (VAS) for pain and narcotic use during postoperative day 1. Secondary endpoints included side effects associated with narcotic administration during the hospital stay. RESULTS: Mean VAS pain in the liposomal bupivacaine PAI group was lower than that for the ropivacaine PAI group at 6 hours (1.8 ± 2.1 versus 3.3 ± 2.3, p = 0.005, mean difference: 1.5, 95% confidence interval [CI], 0.5-2.5) and 12 hours (1.5 ± 2.0 versus 3.3 ± 2.4, p < 0.001, mean difference: 1.8, 95% CI, 0.8-2.8) after surgery. The morphine spinal group had lower pain compared with the liposomal bupivacaine PAI group at 6 hours (0.9 ± 1.8 versus 1.8 ± 2.1, p = 0.035, mean difference: 1.0, 95% CI, 0.1-1.8), but there was no difference at 12 hours (0.8 ± 1.5 versus 1.5 ± 2.0, p = 0.086, mean difference: 0.7, 95% CI, -0.1 to 1.5). The magnitude of the differences at 6 and 12 hours are near the lower end of minimal clinically important differences reported in the literature, and thus the improvement shown in this study may only represent a small clinical improvement. Both the liposomal bupivacaine group (13% [five of 40]) and the ropivacaine group (5% [two of 38]) had fewer incidents of itching (pruritus) than the spinal morphine group (38% [15 of 41]) (p = 0.001). CONCLUSIONS: This prospective multicenter three-arm blind randomized controlled trial showed potentially improved pain control at 6 and 12 hours in the liposomal bupivacaine and intrathecal morphine groups compared with the ropivacaine group at the cost of much higher incidences of pruritus (itching) in the intrathecal morphine group. Based on these results, we prefer the use of PAI with liposomal bupivacaine as an alternative to spinal anesthesia with intrathecal morphine as a result of similar postoperative pain control and the potential for reducing adverse events. LEVEL OF EVIDENCE: Level I, therapeutic study.

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.

Postoperative Pain After Primary Total Knee Arthroplasty: Comparison of Local Injection Analgesic Cocktails and the Role of Demographic and Surgical Factors.

BACKGROUND: It has been reported that pain-related outcomes after total knee arthroplasty (TKA) may vary with different analgesic techniques and with patient demographics. The purposes of this study were to compare local infiltration of regular bupivacaine (periarticular infiltration [PAI] group) vs liposomal bupivacaine (LBUP group) and to examine the effect of patient characteristics on postoperative pain after TKA. METHODS: The study sample included 665 consecutive TKA cases performed between December 2011 and August 2013. The primary outcome measures were the average visual analog scale (VAS) pain score and the percent of VAS pain scores that indicated no pain. Multivariable regression analyses investigated the effect of age, race, ethnicity, body mass index, gender, surgeon, and analgesic protocol on outcomes. For the analgesic groups, the "PAI" group received injections of a cocktail including bupivacaine, ketorolac, and morphine, whereas the "LBUP" group received injections of LBUP. RESULTS: The regression analysis demonstrated that postoperative pain was higher in females (P < .001) and younger patients (P < .001). Although overall average VAS pain scores were not significantly different, when specific postoperative days were evaluated, the LBUP group had lower pain scores from day 1 to 5 (P < .014). There were no differences in VAS scores based on patient body mass index (P = .250), race (P = .205), or ethnicity (P = .961) in this sample. CONCLUSION: This multivariate regression analysis study showed that in patients undergoing primary TKA, postoperative pain was lower in males, older patients, and those treated with LBUP. Awareness of these factors may assist in developing patient-specific multimodal postoperative pain and education protocols that reduce opioid reliance and related adverse events.

How Do Demographic, Surgical, Patient, and Cultural Factors Affect Pain Control After Unicompartmental Knee Arthroplasty? A Multivariable Regression Analysis.

BACKGROUND: Controlling pain after unicompartmental knee arthroplasty (UKA) is essential for improving patient satisfaction, minimizing complications, and early rehabilitation. There is little literature available evaluating the effect of both treatment and patient characteristics on in-hospital pain after UKA. The purpose of this study was to examine the effect of patient and treatment characteristics on in-hospital pain after UKA. This study also evaluated the role of analgesic cocktail (traditional periarticular injection cocktail "[PAI]" vs cocktail including liposomal bupivacaine "[LBUP]"). METHODS: The study sample included 442 consecutive UKA cases performed between December 2011 and August 2013. The primary outcome measures were the average Visual Analog Scale pain score and the percent of pain scores during hospitalization that were 0, that is, "no pain." Multivariable regression analyses were implemented to investigate associations between patient demographics and analgesic group with the outcomes. For the analgesic groups, the "PAI" group received injections of a cocktail including Marcaine, ketorolac, and morphine, the "LBUP" group received injections of LBUP. RESULTS: Postoperative pain was higher in females (P < .001) and younger patients (P = .002). The patient group treated with LBUP injection technique had similar overall average Visual Analog Scale pain scores to patients in the PAI group (P = .729); however, there was also a significant improvement in pain scores over time (as the study progressed) for patients in the LBUP group relative to the PAI group (P = .003), potentially indicating better outcomes with more experience with the injection technique. When compared individually by day, the LBUP group had lower pain scores from day 1 to 3 (P < .024). CONCLUSION: The results showed that in patients undergoing UKA, postoperative pain was lower in males, older patients, patients with lower body mass index, and those treated with LBUP over the study period. Understanding these associations is necessary to effectively manage pain and encourage earlier ambulation and physiotherapy after UKA.

Femoral Nerve Block Versus Long-Acting Wound Infiltration in Total Knee Arthroplasty.

Multimodal wound infiltration analgesic techniques have attracted growing interest for applications in total knee arthroplasty (TKA). A benefit of using wound infiltration instead of femoral nerve block (FNB) in a multimodal pain control regimen is the limitation of muscle strength impairment to the surgical area, which will focus the pain control effort and may provide the opportunity for easier rehabilitation and earlier discharge from the hospital. The current study directly compares patients undergoing TKA who are given a continuous FNB with those who were administered an injection of liposomal bupivacaine infiltration. The study cohort included 36 patients with osteoarthritis who were treated with a continuous FNB (OnQ pump; I-Flow, Lake Forest, California), and 36 patients who were administered an injection for liposome bupivacaine infiltration (EXPAREL; Pacira Pharmaceuticals, Inc, Parsippany, New Jersey) for postoperative pain analgesia. The average number of narcotic doses and the total number of narcotics consumed was greater in the FNB group (P<.001). Average visual analog scale pain scores trended higher for patients in the FNB group (2.29 vs 1.93) overall and for each day postoperatively up to day 5, although the overall difference was not significant in this study sample (P=.115). The results of the current study support the conclusion that long-acting liposome bupivacaine infiltration gives comparable postoperative analgesia compared with a continuous FNB, but with significantly less narcotic medication. [Orthopedics. 2016; 39(3):e449-e455.].

A Comparison of 2 Tibial Inserts of Different Constraint for Cruciate-Retaining Primary Total Knee Arthroplasty: An Additional Tool for Balancing the Posterior Cruciate Ligament.

BACKGROUND: Frequently, a normal posterior-cruciate ligament (PCL) is removed at the surgeon's discretion, converting the normal 4-ligament knee to a 2-ligament knee, thus eliminating the need to balance all 4 ligaments. The development of modular tibial components has led to the availability of differing polyethylene inserts that permit adjustment to the flexion gap independent of the extension gap, permitting PCL balancing not previously available. The purpose of this study is to analyze a specific cruciate-retaining (CR) prosthesis which has 2 polyethylene inserts intended for CR knee use. METHODS: Between February 2004 and February 2013, the senior author (R.H.E.) has performed 930 total knee arthroplasties using the CR flat insert and 424 knees using the CR lipped insert. The inserts were selected during surgery, based on the assessed tension and function of the PCL. The patients were followed up as part of a prospective total joint program with the Knee Society clinical scoring, range of motion, complications, revisions, preoperative coronal deformity, gender, body mass index, and status of the anterior-cruciate ligament intraoperatively. RESULTS: The average Knee Score was 92.4 for the flat group and 92.1 for the lipped group. Average knee flexion was 116.2° for the flat group and 114.4° for the lipped group (P=.2). Average knee extension (flexion deformity) was 2.1° for the flat group and 0.9° for the lipped group CONCLUSION: The results reported here show that clinical outcomes and survivorship were no different for either insert option, leading to indirect evidence that appropriate soft tissue balance had been achieved.

Liposomal Bupivacaine: A Comparative Study of More Than 1000 Total Joint Arthroplasty Cases.

Pain after total joint arthroplasty (TJA) can be severe and difficult to control. A single-dose local analgesic delivers bupivacaine in a liposomal time-release platform. In 2248 consecutive patients with hip and knee arthroplasty, half (Pre) were treated using a well-established multimodal analgesia, including periarticular injection (PAI), and half had the PAI substituted for a liposomal bupivacaine injection technique (Post). Pain scores were significantly lower for patients in the Post group for both hip and knee procedures. A large series of patients who had TJA experienced pain relief after the introduction of liposomal bupivacaine as part of an established multimodal protocol.

Comparison of Local Infiltration Analgesia to Bupivacaine Wound Infiltration as Part of a Multimodal Pain Program in Total Hip Replacement.

Insufficient control of pain after total hip arthroplasty (THA) can delay rehabilitation and adversely affect long-term surgical outcomes. The current study directly compares 36 THA patients who were given a routine wound infiltration (RWI group) with 36 patients who were administered an injection of liposomal bupivacaine infiltration (LBUP group). Average visual analog scale pain scores were significantly higher for RWI patients (2.20 vs. 1.34, p = .0013) overall and trended higher for each day after surgery up to day 5. The average number of opioid doses was 13.14 for the RWI group compared with 4.97 for the LBUP group (p < .0001), and the total opioid dosage consumed was greater in the RWI group (105.4 vs. 72.3, p = .0075; significant only in regression model). The results of this study support the conclusion that liposomal bupivacaine infiltration, as part of a multimodal program after THA, can improve postoperative analgesia and reduce opioid consumption when compared with routine wound infiltration.

The short and "shorter" of it: >1750 tapered titanium stems at 6- to 88-month follow-up.

INTRODUCTION: Femoral fixation in THA can be achieved with different design rationales. Our hypothesis was that two short titanium flat-tapered stems would demonstrate similar stability. METHODS: Between May 2005 and May 2012, 849 short (135-170mm), titanium flat stems ("Short") were used in THA. Between July 2005 and May 2012, 902 similar, but 35-mm shorter, stems ("Shorter") were utilized. Harris Hip Score, radiographic, and survivorship data were analyzed. RESULTS: Survivorship of the "Short" stems was 99.1% at 7years. Eight of 849 stems have been revised: 4 for loosening, 3 for fracture, and 1 for infection. Harris Hip Score improved from 41.6 to 88.9. In the "Shorter" group, 9 of 902 have been revised: 6 for fracture/loosening, 2 for infection, and 1 for instability. HHs improved from 43.7 to 92.0. No statistically significant differences were noted in revision rate. CONCLUSION: This comparison study of short titanium tapered stems has confirmed similar >99% survivorship in >1750 THA stems at 6- to 88 (mean 36)-month follow-up. Early periprosthetic fracture, although rare (0.5%), was more likely to occur in older patients.

Improving patient outcomes through advanced pain management techniques in total hip and knee arthroplasty.

Pain following orthopedic surgery is common and often suboptimally managed, with many patients reporting acute moderate to severe pain following surgery. Opioids are often used to manage this pain, yet this can result in significant side effects and complications, including constipation, nausea, vomiting, respiratory distress, and other central nervous system issues. Multimodal therapy that includes surgical site infiltration with extended release local anesthetic has been seen as a new way to minimize this pain for patients, which can result in improved quality of life and shorter length of hospital stay. This article examines the use of bupivacaine liposome injectable suspension (EXPAREL®; Pacira Pharmaceuticals, Inc., San Diego, California), a non-opioid product for pain management. Liposomal bupivacaine uses DepoFoam® technology that allows for the extended release of injected drugs. When used as the foundation of a multimodal regimen, it is effective in reducing postsurgical pain for up to 72 hours while reducing the need for opioids for pain relief.

Increased anteversion of press-fit femoral stems compared with anatomic femur.

BACKGROUND: With contemporary canal-filling press-fit stems, there is no adjustability of stem position in the canal and therefore the canal anatomy determines stem version. Stem version will affect head/neck impingement, polyethylene wear from edge loading, and hip stability, but despite this, the postoperative version of a canal-filling press-fit stem is unclear. QUESTIONS/PURPOSES: Is there a difference between the version of the nonoperated femur and the final version of a canal-filling press-fit femoral component? Could a difference create an alignment problem for the hip replacement? METHODS: Sixty-four hips were studied with fluoroscopy and 46 nonarthritic and 41 arthritic hips were studied with MRI. A standardized fluoroscopic technique for determining preoperative and postoperative femoral version was developed with the patient supine on a fracture table undergoing supine total hip arthroplasty. To validate the methods, the results were compared with two selected series of axial MRI views of the hip comparing the version of the head with the version of the canal at the base of the neck. RESULTS: For the operated hips, the mean anatomic hip version was less than the stem version: 18.9° versus 27.0°. The difference on average was 8.1° of increased anteversion (SD, 7.4°). Both MRI series showed the femoral neck was more anteverted on average than the femoral head, thereby explaining the operative findings. CONCLUSION: With a canal-filling press-fit femoral component there is wide variation of postoperative component anteversion with most stems placed in increased anteversion compared with the anatomic head. The surgical technique may need to adjust for this if causing intraoperative impingement or instability.

Men versus women: does size matter in total knee arthroplasty?

UNLABELLED: The role played by femoral component sizing in the clinical outcome of primary TKA is currently debated. Oversizing the femur in patients with smaller knees could lead to overstuffing the knee capsule with resulting pain and reduced range of motion. We asked whether the distribution of femoral component sizes differed between genders and whether the availability of additional sizes benefited genders differently and led to a measurable improvement in knee flexion and Knee Society scores or pain. We retrospectively examined two groups of consecutive knees of patients who underwent primary TKA using similar techniques and constraint: Group 1 (93 men and 90 women) who had available four original sizes and Group 2 (106 men and 106 women) after the introduction of three new smaller sizes. More than twice as many new smaller sizes were used in women (52.3%, 56 of 106) compared to men (17.9%, 19 of 106). At the scheduled 6-month followup visit (average, 6 months; range, 5-7 months), we found no differences in the knee score, pain score, and knee flexion in men and women before the additional sizes (Group 1) and after the new sizes (Group 2). Additional sizes therefore did not appear to influence short-term outcomes. LEVEL OF EVIDENCE: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Unicompartmental knee arthroplasty with the oxford prosthesis in patients with medial compartment arthritis.

BACKGROUND: The mobile-bearing feature of the Oxford unicompartmental knee replacement has the potential to optimize polyethylene wear, thereby leading to longer-term function of the implant. The function of the bearing requires intact soft tissues, with the ligaments being balanced throughout the range of motion intraoperatively through bone resection only. Final limb alignment is determined by the restored soft-tissue tension. The purposes of this study were to determine the limb alignment achieved in the absence of ligament release and to investigate the interplay of failure mode, survivorship, and limb alignment. METHODS: Fifty-five knees in fifty-one patients with medial compartment osteoarthritis had a unicompartmental replacement with an Oxford prosthesis. Evaluation included Knee Society clinical scores, radiographic evaluation, survivorship analysis, and modes of failure. The average duration of clinical follow-up was 11.8 years. Only two patients (three knees) were lost to follow-up. RESULTS: The mean postoperative Knee Society knee score and function score at the latest follow-up evaluation were 75 and 90 points, respectively. The overall alignment of the knee was restored to neutral, averaging 5.6 degrees of valgus alignment. Forty-seven of the fifty-five knees had the mechanical axis crossing the central 50% of the tibial plateau. Seven knees had revision surgery, and six of them required conversion to a total knee prosthesis. The main reason for revision was the progression of arthritis in the lateral compartment, which occurred in four knees at an average of 10.2 years postoperatively. These four knees had not been overcorrected into excessive valgus at the time of the original surgery, and we found no correlation, with the numbers studied, between alignment and bearing size. Survivorship analysis showed that the rate of survival at ten years was 85% with failure for any reason as the end point, 90% with progression of lateral compartment arthritis as the end point, and 96.3% with component loosening as the end point. CONCLUSIONS: With this unicompartmental knee arthroplasty, the mechanical limb alignment resulting from balancing the knee ligaments, accomplished without releasing them, was consistently through the center of the knee. Progression of arthritis in the lateral compartment was the most common reason for late failure in this series and was not related to the initial postoperative alignment.

Preoperative and postoperative limb alignment after Oxford unicompartmental knee arthroplasty.

From a series of 64 sequential Oxford (Biomet Orthopedics, Inc, Warsaw, phase 3 implants, two study groups were selected: 23 knees with unilateral surgery and a normal opposite side, and 21 knees with bilateral simultaneous surgery. Standing 3-foot radiographs were taken pre- and postoperatively to assess the femorotibial angle and the location of the mechanical axis of the limb in relation to the knee. Results in the unilateral group showed an average postoperative femorotibial angle of 4.50 was compared to a 3.40 angle for the normal side, (not significantly different; P=.09). Results for the bilateral group were an average postoperative femorotibial angle of 3.40 for the right and 3.50 for the left, (not significantly different; P=.7). The location of the mechanical axis was similar between the knees in both groups. The study concludes that the Oxford soft-tissue balancing technique restores alignment, which is on average similar to the opposite side, and therefore presumably normal for that knee. Restoration of normal alignment should not put excess stress onto the lateral compartment.

Metal-on-metal total hip arthroplasty with large heads may prevent early dislocation.

UNLABELLED: Postoperative dislocation is one of the major causes of morbidity and failure of total hip arthroplasty. We reviewed 327 patients (377 hips) retrospectively with varying diagnoses and indications but all of whom received large-diameter metal-on-metal prostheses. Two surgical approaches were used: the anterolateral abductor splitting (342 procedures) and a mini-incision posterior approach (35 procedures). Average age at time of surgery was 55.9 years and average followup was 4.0 months. There were 346 (91.8%) primary procedures, 15 (4.0%) conversion procedures, and 16 (4.2%) revisions or reimplantations. The most common preoperative diagnoses included osteoarthritis (250 hips; 66.3%) and avascular necrosis (46 hips; 12.2%). There were 62 (16.4%) patients with high-risk diagnoses for dislocation. The status in terms of postoperative dislocation was known for all patients. During the short followup period, there were no dislocations. Use of large-diameter femoral heads and metal-on-metal articulations decreases the risk of dislocations, making their use a viable choice for primary and revision procedures. LEVEL OF EVIDENCE: Therapeutic study, Level IV-1 (case series). See the Guidelines for Authors for a complete description of levels of evidence.