Can the Visibility of Both Prosthetic Posterior Femoral Condyles on a Postoperative Radiograph Assure that Limb Rotation Is Appropriate to Allow Accurate Measurement of the Anatomic Knee Axis?

BACKGROUND: To better define radiographic parameters for a true anterior-posterior (AP) knee radiograph after total knee arthroplasty, we cataloged the radiographic appearance of 7 different designs of commercially available femoral components at various points of rotation to correlate the visibility of the prosthetic posterior femoral condyles (PPFCs) with the amount of rotation of the femoral component, and hence, the limb. METHODS: AP radiographs of 7 left-sided, cruciate-retaining femoral trial components were obtained at 5° increments of rotation from 20° internal rotation (IR) to 20° external rotation (ER). Rotational profiles were cataloged based on the visibility of either or both of the PPFCs. RESULTS: Three categories of femoral component rotation profiles were noted, based on the visibility of the PPFC: overt ER with only the medial PFC visible at greater than 10° ER, overt IR with only the lateral PFC visible at greater than 20° IR, and near-neutral rotation with both medial and lateral PPFCs visible between 5° ER and 15° IR. CONCLUSION: An acceptable AP radiograph to measure the anatomic knee axis after total knee arthroplasty is one where both the medial and lateral PPFCs are visible on either side of the trochlear flange.

The Effect of Patellar Thickness on Intraoperative Knee Flexion and Patellar Tracking in Patients With Arthrofibrosis Undergoing Total Knee Arthroplasty.

BACKGROUND: We evaluated the intraoperative effect of patellar thickness on intraoperative passive knee flexion and patellar tracking during total knee arthroplasty (TKA) in patients with preoperative arthrofibrosis and compared them to patients with normal preoperative range of motion (ROM) documented in a prior study. METHODS: Routine posterior cruciate ligament-retaining TKA was performed in a total of 34 knees, 23 with normal ROM and 11 with arthrofibrosis, defined as ≤100° of passive knee flexion against gravity under anesthesia. Once clinical balance and congruent patellar tracking were established, custom trial patellar components thicker than the standard trial by 2-mm increments (2-8 mm) were sequentially placed and trialed. Passive flexion against gravity was recorded using digital photograph goniometry. Gross mechanics of patellofemoral tracking were visually assessed. RESULTS: On average, passive knee flexion decreased 2° for every 2-mm increment of patellar thickness (P < .0001), which was similar to patients with normal preoperative ROM. In addition, increased patellar thickness had no gross effect on patellar subluxation and tilt in patients with arthrofibrosis as well as those with normal ROM. CONCLUSIONS: Patellar thickness had a modest effect on intraoperative passive flexion and no effect on patellar tracking in patients with arthrofibrosis undergoing TKA. There was no marked difference in intraoperative flexion and patellar tracking between patients with arthrofibrosis and patients with normal preoperative ROM.

Does increased topside conformity in modular total knee arthroplasty lead to increased backside wear?

BACKGROUND: Modular metal-backed tibia components allow surgeons intraoperative flexibility. Although it is known that modular tibia components introduce the possibility for backside wear resulting from relative motion between the polyethylene insert and the tibial baseplate, it is not known to what degree variability in the conformity of the tibial polyethylene liner itself might contribute to backside wear. QUESTIONS/PURPOSES: The purpose of this study was to determine whether a flat, cruciate-retaining tibial polyethylene bearing generates less backside wear than a more conforming (curved) tibial polyethylene bearing in an analysis of specimens explanted during revision surgery. METHODS: The study included 70 total knee inserts explanted at revision surgery, all implanted and explanted by the same surgeon. Two different cruciate-retaining insert options in an otherwise similar knee system were used: one with a curved-on-flat (17) articular geometry and one with a highly conforming curved-on-curved design (53); both groups were sequential cohorts. The composite backside wear depth for the insert as well as the volume of backside wear was measured and compared between groups. RESULTS: The median linear backside-normalized wear for the posterior lipped inserts was 0.0063 mm/year (range, 0-0.085 mm/year), which was lower than for the curved inserts at 0.05 mm/year (range, 0.00003-0.14 mm/year) (p<0.001). The median calculated volumetric backside-normalized wear for the posterior lipped inserts was 14.2 mm3/year (range, 0-282.8 mm3/year) compared with 117 mm3/year (range, 2.1-312 mm3/year) for the curved inserts (p<0.001). CONCLUSIONS: In this retrieval study, more conforming tibial inserts demonstrated more backside-normalized wear than the flatter designs. This suggests that in this modular total knee arthroplasty design, higher articular conformity to address the issues of high bearing contact stress comes at a price: increased torque transmitted to the backside insert-to-tray interface. We suggest further work be undertaken to examine newer insert designs to evaluate if our conclusions hold true with the newer generation locking mechanism, tibial tray finish and polyethylene designs, as more highly conforming tibial inserts are introduced into the market. LEVEL OF EVIDENCE: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Cruciate-retaining TKA is an option in patients with prior patellectomy.

BACKGROUND: The recommendation for using posterior-stabilized (PS) implants in patellectomy patients undergoing total knee arthroplasty (TKA) is based on older case series with heterogeneous patient populations. The use of cruciate-retaining implants in these patients has not been evaluated with more contemporary implant designs. QUESTIONS/PURPOSES: The purpose of this study was to evaluate the survivorship and functional outcomes (Knee Society score, presence of an extensor lag, and range of motion) of cruciate-retaining (CR) TKA in patients with prior patellectomy. METHODS: Between 1986 and 2012, we performed 27 CR TKAs in 25 patients after patellectomy. Of those, 23 CR TKAs in 21 patients were available for followup at a minimum of 2 years (mean, 11.2 years; range, 2.3-25.1 years). In this retrospective study, we queried a prospectively maintained database to assess functional outcomes and survivorship. RESULTS: Aseptic loosening-free survival was 100% at 5 and 10 years, and survival with revision for any reason as the outcome was 96% at 5 years (95% confidence interval [CI], 87.7%-100%) and 84% at 10 years (95% CI, 69.5%-100%). One patient was revised for aseptic loosening at 10.2 years postoperatively. Mean Knee Society scores improved from 36±13 preoperatively to 92±9.6 at followup. Extensor lag was present in seven patients preoperatively and only three at followup. Average knee flexion at followup was 112°±12.5°. CONCLUSIONS: In this study we found good long-term survivorship and functional outcomes with a CR implant design in patients following patellectomy. Earlier studies have favored PS over CR implants for patients with patellectomies. We believe this series suggests that CR TKA is indeed an option in patients with patellectomy. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The Incidence and Short Term Functional Effect of Partial PCL Release in Fixed and Mobile Bearing PCL Retaining TKA.

Posterior cruciate ligament (PCL) release may be required to balance the flexion gap in PCL retaining TKA. This study examines the incidence and functional consequences of PCL release in both fixed and mobile bearing TKA. A consecutive series of 1388 TKAs with 1014 fixed bearing, and 374 mobile bearing implants were reviewed for prevalence of partial PCL release, restoration of potential flexion and objective knee stability at minimum one-year follow-up. Patients receiving mobile bearing inserts were more likely to need partial PCL release (42% versus 17.5%). The occurrence of partial PCL release did not have a significant impact on knee range of motion and subjective knee stability. The need for a partial PCL release appears to be greater in mobile than in fixed bearing. Knees that required a release in both groups demonstrated no difference in restoration of flexion compared with unreleased knees and no adverse effects on flexion stability.

Consensus Statement on Indications and Contraindications for Medial Unicompartmental Knee Arthroplasty.

Previous work, now nearly 30 years dated, is frequently cited as the "gold standard" for the indications and contraindications for medial unicompartmental knee arthroplasty (UKA). The purpose of this article is to review current literature on the indications and contraindications to UKA and develop a consensus statement based on those data. Six surgeons with a combined experience of performing more than 8,000 partial knee arthroplasties were surveyed. Surgeons then participated in a discussion, emerging proposal, collaborative modification, and final consensus phase. The final consensus on primary indications and contraindications is presented. Notably, the authors provide consensus on previous contraindications, which are no longer considered to be contraindications. The authors provide an updated and concise review of the current indications and contraindications for medial UKA using scientifically based consensus-building methodology.

Total knee arthroplasty in patients with juvenile idiopathic arthritis.

BACKGROUND: Total knee arthroplasty (TKA) for juvenile idiopathic arthritis is rare but is nonetheless indicated for many patients with this disease. Few reports exist on the results of TKA in patients with juvenile idiopathic arthritis. QUESTIONS/PURPOSES: It was sought to determine (1) survivorship and (2) functional outcomes of TKAs in patients with juvenile idiopathic arthritis. METHODS: Results were combined from patients treated by experienced surgeons at five hospitals between 1979 and 2011. Two hundred nineteen patients (349 TKAs) were identified and contacted to survey their outcomes at a minimum followup of 2 years (mean, 12 ± 8 years; range, 2-33 years). The average age at surgery was 28.9 ± 9.7 years (range, 11-58 years). Data on revision surgery and ability to perform daily activities were collected. RESULTS: The 10-year survivorship was 95%, decreasing to 82% by 20 years. At latest followup, 31 of 349 TKAs (8.9%) had been revised for either polyethylene failure or loosening (18 TKAs), infection (four), stiffness (three), periprosthetic fractures (two), bilateral amputation for vascular reasons (two), patellar resurfacing (one), and instability (one). Walking tolerance was unlimited in 49%, five to 10 blocks in 23%, and less than five blocks in 28%. Eleven percent could not manage stairs, and another 59% depended on railings. A cane was used by 12% and crutches by 7%; 12% were wheelchair-dependent. CONCLUSIONS: TKA survivorship in patients with juvenile idiopathic arthritis was inferior to that typically seen in younger patients with osteoarthritis or even rheumatoid arthritis confirming results of earlier studies with smaller patient numbers. This is especially disconcerting because younger patients require better durability of their TKAs.

Simultaneous bilateral knee arthroplasty in octogenarians: can it be safe and effective?

Simultaneous bilateral knee arthroplasty (SBTKA) in octogenarians is controversial. Our purpose was to review the outcomes of octogenarians undergoing SBTKA. All patients greater than 80 years of age who underwent SBTKA by a single surgeon were retrospectively evaluated. Fifty-six patients with an average age of 82.5 years were identified. Twelve postoperative complications occurred. Three were serious; two non-fatal PEs and one wound debridement. Minor complications included UTI, decubitus ulcer, DVT, confusion, transfusion reaction and ileus. Average postoperative survival was 7.4 years. No deaths occurred within 30 days postoperatively. Simultaneous bilateral total knee arthroplasty can be a safe and effective option for octogenarians. Complications and mortality are not higher for SBTKA compared to UTKA in this population.

Magnitude of limb lengthening after primary total knee arthroplasty.

Patients will often perceive a change in lower limb length after total knee arthroplasty (TKA). From this observed finding, we asked how frequently does a change in limb length occur after TKA. Preoperative and postoperative full-length standing radiographs were obtained for 102 knees in 98 patients who underwent TKA. Digital radiography software was used to measure the mechanical axis and limb length of the operative and nonoperative legs. Overall, 83% of the knees measured showed an increase in limb length after TKA. Preoperative varus alignment was associated with an average lengthening of 5.2 mm. Preoperative valgus alignment was associated with an average lengthening of 8.4 mm. Patients with a valgus deformity greater than 10° demonstrated the greatest average lengthening. It is the conclusion of this study that limb lengthening occurs frequently after TKA, back to a length similar to the nonoperative limb.

Mobile- versus fixed-bearing unicompartmental knee arthroplasty.

Unicompartmental knee arthroplasty using either a mobile- or fixed-bearing technique is an attractive alternative to osteotomy or total knee arthroplasty in selected patients with osteoarthritis. Both techniques appear to yield equivalent early results. Mobile-bearing articulations have the advantage of allowing a metal-backed component to be used with a composite thickness as thin as 6 mm. They also offer the potential for decreased long-term wear complications because of the high conformity of the articulation. The longevity of fixed-bearing components will likely be improved in the future with better prosthetic designs and improved polyethylene to minimize the incidence of late wear complications.

Custom-made angled inserts for tibial coronal malalignment in total knee arthroplasty.

Component malalignment continues to be common after knee arthroplasty, with treatment often requiring prosthesis revision. From 1993 to 2005, 9 angled inserts were placed to correct coronal plane deformities due to tibial component malposition. Insert exchange occurred at an average of 67 months (range, 5-149 months) from the index procedure. Two patients died before 2-year follow-up, for an overall average of 60 months (range, 12-157 months) follow-up. Limb alignment improved and Knee Society knee and function scores increased from 68 and 71, respectively, to 92 and 91, postoperatively. All patients reported excellent satisfaction with no revisions at average 5-year follow-up. It is important to be aware that specifically designed angled inserts are available and may provide a conservative method to correct mild to moderate tibial malalignment in rare cases.

Efficacy of manipulation under anesthesia beyond three months following total knee arthroplasty.

BACKGROUND: Stiffness after total knee arthroplasty (TKA) is often treated with manipulation under anesthesia (MUA) to improve range of motion (ROM). However, many authors recommend against MUA beyond 3 months after TKA. This study investigates the timing of MUA for stiffness after TKA, focusing on MUA performed at >12 weeks. METHODS: In total, 142 MUAs were retrospectively reviewed. "Early" MUAs were at <12 weeks after TKA; "Late" MUAs were >12 weeks. MUAs were further subdivided into 4 groups: 83 "Group I" cases at <12 weeks, 34 "Group II" between 12 and 26 weeks, 12 "Group III" between 26 and 52 weeks, and 13 "Group IV" at >52 weeks. Gains in ROM were compared between groups. RESULTS: Gains in flexion and overall ROM were statistically equivalent in Early vs Late MUA when controlling for pre-MUA ROM. ROM gains between the early Group I and the later Groups II-IV were also statistically comparable. Overall ROM gain in Group I was 24.1°, 17.9° in Group II, 20.8° in Group III, and 11.1° in Group IV. There were no significant complications. CONCLUSIONS: Early and late MUA resulted in statistically equivalent gains in ROM, regardless of timing after TKA. All groups showed an average improvement in ROM of ≥11°. MUA performed beyond 3 months, and even beyond 1 year, appears to be safe and may improve ROM and allow select patients to avoid revision surgery.

Nanoparticulate fillers improve the mechanical strength of bone cement.

BACKGROUND AND PURPOSE: Polymethylmethacrylate (PMMA-) based bone cement contains micrometer-size barium sulfate or zirconium oxide particles to radiopacify the cement for radiographic monitoring during follow-up. Considerable effort has been expended to improve the mechanical qualities of cements, largely through substitution of PMMA with new chemical structures. The introduction of these materials into clinical practice has been complicated by concerns over the unknown long-term risk profile of these new structures in vivo. We investigated a new composite with the well characterized chemical composition of current cements, but with nanoparticles instead of the conventional, micrometer-size barium sulfate radiopacifier. METHODS: In this study, we replaced the barium sulfate microparticles that are usually present in commercial PMMA cements with barium sulfate nanoparticles. The resultant "microcomposite" and "nanocomposite" cements were then characterized through morphological investigations such as ultra-small angle X-ray scattering (USAXS) and scanning electron microscopy (SEM). Mechanical characterization included compression, tensile, compact tension, and fatigue testing. RESULTS: SEM and USAXS showed excellent dispersion of nanoparticles. Substitution of nanoparticles for microparticles resulted in a 41% increase in tensile strain-to-failure (p = 0.002) and a 70% increase in tensile work-of-fracture (p = 0.005). The nanocomposite cement also showed a two-fold increase in fatigue life compared to the conventional, microcomposite cement. INTERPRETATION: In summary, nanoparticulate substitution of radiopacifiers substantially improved the in vitro mechanical properties of PMMA bone cement without changing the known chemical composition.

Correcting flexion contractures: getting it straight.

Many factors play a role in causing a flexion contracture associated with TKA. The final goal of correction is to achieve and maintain a contracture that is < 15 degrees. Contractures between 10 degrees and 15 degrees may still be symptomatic, and those < or = 10 degrees are rarely a problem. Perioperative and intraoperative treatment measures exist to alleviate flexion contractures. Intraoperative correction determines the final result in most cases, except in inflammatory cases where the preoperative contracture is > 40 degrees. In these cases, under anesthesia the preoperative contracture need only be corrected to within one-third of its initial amount, and the remainder will usually resolve with postoperative physical therapy and serial casting or splinting.

Early Regain of Function and Proprioceptive Improvement Following Knee Arthroplasty.

BACKGROUND: Techniques that allow early muscle activation, such as closed kinetic chain (CKC) and open kinetic chain (OKC) exercises, may play a beneficial role in the early rehabilitation of the reconstructed knee. However, current rehabilitation regimens have not been shown to reverse post-operative quadriceps activation failure and weakness. To investigate whether patients who use a continuous active motion (CAM) device that follows closed kinetic chain principles have better early post-operative functional improvements than patients who use a continuous passive motion (CPM) device that follows the principles of open kinetic chain principles. A prospective randomized controlled trial with non-blinded study staff. A tertiary care clinic at a teaching hospital. A total of 110 patients signed the consent form and 83 patients participated in the study. METHODS: Patients were randomly assigned to use either the CPM device for 4 hours daily for 3 weeks (control group), or a CAM device for 3 sessions of 20 minutes for 3 weeks (intervention group), starting 24 hours after knee replacement surgery.The primary outcome measure was to identify the superiority, inferiority, or equivalence of one device at week 4 after knee arthroplasty using various functional outcome measures such as kinesthesia, quadriceps strength, coordination, general orthopaedic outcome measures and narcotic consumption. RESULTS: At 4 weeks, all outcome measurements were comparable between the two groups, with the exception of sit-to-stand test: in the treatment group the time was significantly shorter compared to the control group (P=0.016). Balance was significantly better in both control (P=0.001) and treatment group (P=0.032) compared to prior surgery. CONCLUSION: Most clinical centers would like to expedite functional recovery of knee arthroplasty patients without increasing the risk of falls. We observed balance and kinesthesia improvements after surgery using either device which may be important to benefit fast recovery programs. Further research is warranted to see whether additional active closed kinetic chain exercised following knee replacement surgery could improve specific functional outcomes such the observed sit-to-stand test. LEVEL OF EVIDENCE: I.

Lateral unicompartmental knee arthroplasty through a medial approach. Study with an average five-year follow-up.

BACKGROUND: Unicompartmental knee arthroplasty of the medial compartment has excellent long-term clinical outcomes. Arthritis isolated to the lateral compartment is much less common; subsequently, the clinical outcomes of the treatment of that condition are less frequently reported. Most commonly, the lateral compartment is approached through a lateral arthrotomy. The purpose of this study was to determine the mid-term results of lateral unicondylar replacement through a medial arthrotomy in patients with primary osteoarthritis or posttraumatic arthritis. METHODS: From 1991 to 2004, forty-nine lateral unicompartmental knee arthroplasties were performed in forty-five patients by a single surgeon. One patient was excluded from the study because of a severe underlying neurologic condition. Lateral unicompartmental replacement was performed in thirty-eight knees with primary osteoarthritis and in ten knees with posttraumatic arthritis secondary to a tibial plateau fracture. Retrospective chart reviews and radiographic evaluations were performed, and Knee Society scores were determined. RESULTS: The average Knee Society knee and function scores improved from 39 and 45 points, respectively, preoperatively to 89 and 80 points at an average of 5.2 years postoperatively. Preoperative alignment averaged 10 degrees of valgus, which was corrected to an average of 6.2 degrees of valgus postoperatively. There were no revisions and no notable soft-tissue complications. The mean postoperative knee and function scores were significantly better for patients with primary osteoarthritis (95 and 86 points, respectively) than they were for those with posttraumatic arthritis (74 and 65 points). CONCLUSIONS: Lateral unicompartmental knee replacement through a medial approach provided durable and reliable short to mid-term results. This approach is safe, effective, and extensile, making it a viable alternative to a lateral approach. The outcomes of lateral unicompartmental replacement in patients with posttraumatic arthritis can be expected to be inferior to those in patients with primary osteoarthritis.

Late hematogenous infections after total knee arthroplasty: experience with 3013 consecutive total knees.

Newer technologies have seen a gradual decline in mechanical causes for total knee arthroplasty (TKA) failures. As these mechanical mechanisms of failure have slowly diminished, infections have come to comprise an even larger proportion of complications in knee replacement surgery. This article presents a retrospective review of a single surgeon's incidence of late hematogenous infections after 3013 consecutive primary TKAs using a standard surgical technique. Fifteen late hematogenous infections were found in 14 (0.5%) patients at an average of 10 years postoperatively. The surgical protocol is reported and the late infections are analyzed for their etiologies and outcomes.

Sebaceous glands in esophagus in gastroesophageal reflux disease.

Sebaceous glands in the esophagus are very rare and have been reported mostly in autopsy studies. They have been considered to be of no clinical significance. We report a 50-year-old man with gastroesophageal reflux disease who had sebaceous glands in the esophagus on endoscopic biopsy.