A Restricted Functional Balancing Technique for Total Knee Arthroplasty With a Varus Deformity: Does a Medial Soft-Tissue Release Result in a Worse Outcome?

BACKGROUND: A functional alignment technique for total knee arthroplasty (TKA) utilizes implant position modifications to balance the soft tissues. There is concern that, in some cases, extreme coronal and tibial component alignment could facilitate early implant failure. To be cautious, a restricted functional alignment may be used. The purpose of our study was to evaluate the results of TKA in patients who have varus deformities using a restricted functional alignment technique. We hypothesized that adding a medial soft-tissue release within restricted boundaries would not result in inferior outcomes. METHODS: A retrospective review was performed on robotic arm-assisted TKA patients with varus deformities utilizing a functional balancing strategy with a three-degree varus coronal limb and tibial component alignment restriction. Outcome scores of those patients still requiring a medial-soft tissue release were compared to those without for inferior outcomes. RESULTS: A total of 202 of 259 (78.0%) knees were able to be balanced without any medial soft-tissue release with an average final hip-knee-ankle alignment of 1.9° varus. The remaining 57 knees required a medial soft-tissue release. They had an average final hip-knee-ankle of 2.8° varus and an average medial proximal tibial angle of 2.5° varus. Comparing the cohorts without and with a release, at final follow-up averaging two years, there was not a statistically significant difference in Knee Society-Knee Score (97.7 and 98.4, P = .525), Functional Score (86.7 and 88.7, P = .514), Forgotten Joint Score (59.8 and 66.6, P = .136), and Knee Injury Osteoarthritis Outcome Survey for Joint Replacement Junior Score (79.5 and 84.8, P = .066). CONCLUSIONS: Utilizing a restrictive functional balancing strategy for TKA minimizes the need for soft-tissue releases and provides for excellent overall outcomes. An additional medial soft-tissue release can still be utilized without an inferior average two-year outcome.

Metal-Backed Patella Implants in Knee Arthroplasty: Can the Past Predict the Future?

BACKGROUND: There is a renewed interest in uncemented total knee arthroplasty to potentially provide longer durability, including the use of newer design metal-backed patellae (MBPs). The purpose of this study was to review survivorship with failure mode and time to failure of an earlier version MBP at up to 10-30 years of follow-up that may influence the desirability of using these components today. METHODS: A retrospective review was performed of patients that had uncemented total knee arthroplasty with an uncemented MBP. All-cause revision rates were obtained from chart reviews and telephone discussions with patients and family members of deceased patients. Kaplan-Meier plots were used to determine the implant survivorship. Outcome scores were compared between revised and nonrevised patients. RESULTS: The 97 knees that had an end point of an aseptic revision or last known contact with implant survivorship averaged 15 years (range, 0-32 years). There were 40 knees that underwent revision that included 37 patella component failures (38.1%). All patellar failures had polyethylene wear or fracture. None were revised due to loosening. Survivorship was 97.9% at 5 years, 88.7% at 10 years, and 53.0% at 20 years. Median time to failure was 11 years. CONCLUSION: Loosening is not a failure mode with this MBP. There were 75% of the failures occurring after 10 years. Use of contemporary MBP with improved but still thin polyethylene warrants guarded optimism when used in younger patients where longer survivorship than with a cemented all-polyethylene patellar component is the goal.

Effect of Posterior Osteophytes on Total Knee Arthroplasty Coronal Soft Tissue Balance: Do They Matter?

BACKGROUND: Achieving coronal plane balance in total knee arthroplasty (TKA) is of paramount importance. There is concern that obtaining balancing before removal of posterior osteophytes may lead to asymmetrical extension balance once removed. We hypothesized that there is a particular posterior osteophyte size and location that does not result in significant change in coronal gap balancing. METHODS: In this study of 245 robotic arm-assisted TKAs, the size and location of posterior osteophytes were obtained from preoperative computer tomography scans. Gap measurements at 10°-25° and 90° flexion after removal of medial and lateral osteophytes, before and after posterior osteophyte removal and bone resection were compared with respect to the size and location of posterior osteophytes. RESULTS: The largest size posterior osteophytes measured >10 mm in 8.2% of cases, 5-10 mm in 34.7%, <5 mm in 23.7%, and 23.7% had no osteophytes. The mean osteophyte size was 5.7 mm. The cohorts with and without posterior osteophytes were both found to have significant but similar changes in all gaps after osteophyte removal and bone resection (mean 0.8-1.4 mm, P < .0001 and mean 0.7-1.7 mm, P < .0001, respectively). Osteophyte size and location had no significant effect on the change in postresection gaps. This included osteophytes greater than 10 mm, but their incidence was small. CONCLUSION: There is a small significant change in gaps between initial assessment and subsequent TKA bone resections, with or without posterior osteophytes. Our study found that where the surgeon thoroughly removes the medial and lateral osteophytes on initial exposure, posterior osteophytes <10 mm can be ignored during initial knee coronal balancing.

New Technology for Total Knee Arthroplasty Provides Excellent Patient-Reported Outcomes: A Minimum Two-Year Analysis.

INTRODUCTION: Robotic-assisted total knee arthroplasty has been demonstrated to help increase various patient-reported, clinical, and surgical outcome metrics (PROMs). However, the current literature is limited regarding PROMs data for longer follow-up periods beyond one year. Therefore, the purpose of this study was to 1) report multicenter patient-reported outcomes with multiple metrics, as well as 2) postoperative surgeon-specific outcomes at a minimum two-year follow-up. MATERIALS AND METHODS: Five fellowship-trained, high-volume surgeons performed a total of 188 total knee arthroplasty surgeries using the enhanced preoperative planning and real-time intraoperative feedback of a robotic-assisted device. Patients from all surgeons followed similar postoperative rehabilitation beginning on postoperative day one. Patients were evaluated based on the Short Form-12 Questionnaire (SF-12), the Forgotten Joint Score (FJS), and Knee Society total and subscores (KSS). The SF-12 was subdivided into two components: mental composite score (MCS) and physical composite score (PCS). The KSS was subdivided into functional and knee scores. Additionally, surgical outcomes from the latest follow-up visit were evaluated. All patients were evaluated at a minimum of two years follow-up time. RESULTS: All patients reported excellent postoperative outcomes for all three PROMs. The mean postoperative SF-12 MCS and PCS scores were both 57 points, with 50 as the threshold for norm-based scoring (MCS range: 42 to 69 points; PCS range: 41 to 68 points). The mean FJS was 75 points (range: 14 to 100 points). The mean KSS functional score was 84 points (range: 20 to 100) while the mean Knee Score was 92 points (range: 40 to 100). Similarly, we found that the aseptic revision rates were low (n=2, 1.06%, one for unexplained pain, and another for a post-traumatic tibial fracture) with few other postoperative complications (n=7 patients [3.7%]) in our cohort. CONCLUSION: Our analysis found that patients had excellent outcomes across multiple PROM metrics. Future work can build on these results with large patient populations over longer follow-up intervals. Nevertheless, these results provide the foundation and evidence to support the continued use of this innovative technology for total knee arthroplasties.

Manipulation Under Anesthesia Rates in Technology-Assisted versus Conventional-Instrumentation Total Knee Arthroplasty.

INTRODUCTION: Various technological advancements, specifically robotic assistance, have been implemented for total knee arthroplasty (TKA) procedures to attempt to improve patient outcomes and decrease complication rates. Manipulations under anesthesia have been considered a surrogate for knee stiffness, an undesired postoperative outcome that can potentially be avoided. Currently, there is a lack of information regarding the impact that these new technologies have on manipulations under anesthesia (MUA) rates following TKA. Therefore, the purpose of this study was to evaluate rates of MUAs between a consecutive series of patients who underwent robotic-assisted surgery compared to patients who underwent TKA with conventional instrumentation. MATERIALS AND METHODS: A total of 188 consecutive robotic-assisted total knee arthroplasties were performed by five fellowship-trained, high-volume surgeons at academic and community institutions. Patients were paired to a consecutive equal number of control patients by each of the specific surgeon for comparison. All patients followed similar postoperative rehabilitation starting on postoperative day one. Rates of MUAs were evaluated within and between cohorts. Additionally, the percent difference of rates was calculated to compare cohorts. All patients were evaluated at a minimum of two years follow-up time from the index procedure. Chi-square analyses was performed to statistically compare MUA rates between the cohorts. RESULTS: The overall manipulation under anesthesia rate for the study cohort was 1.06% (2/188 patients), while it was 4.79% in the control cohort (9/188) (p=0.032). A 127.5% difference in manipulation under anesthesia rates was found between the two cohorts. No individual surgeons had higher MUA rates in their robotic-assisted group. CONCLUSION: Our study found that patients undergoing robotic-assisted TKA experienced a significant, 4.5-fold decrease in rates of manipulation under anesthesia (p=0.032). Given that MUAs can be a marker of knee stiffness following total knee arthroplasty, the lower rate indicates that study cohort patients had less knee stiffness and, therefore, greater initial postoperative range of motion than the control cohort. Based on these data, assistive technologies may have an advantageous role contributing to enhanced patient outcomes.

All-Polyethylene Tibial Component Use for Elderly, Low-Demand Total Knee Arthroplasty Patients.

BACKGROUND: Potential advantages combined with lower cost have prompted a renewed interest in modern all-polyethylene tibial designs. METHODS: A total of 317 Natural Knee total knee arthroplasties with an all-polyethylene tibial component that was performed since 1993 were retrospectively reviewed to confirm that cost savings were not associated with inferior clinical results. They were primarily used in elderly, low-demand patients. The average age at the time of surgery was 80.8 years. RESULTS: 227 knees with a minimum of 2-year follow-up were identified. The average follow-up was 5.6 years (range, 2-20 years). Clinical and radiographic outcomes were evaluated. At the latest follow-up, the average Knee Society and functional score was 94.2 and 57.2. The average postoperative range of motion was 1.6°-115.4°. No patient required a revision for aseptic or septic loosening, wear, or instability. Only 5 knees had a partial nonprogressive cement/bone radiolucency. There was an approximate 33% cost savings for the implants when the all-polyethylene component was used. CONCLUSION: An all-polyethylene tibial component of this design provides excellent results in the elderly population along with a significant cost savings.

A Targeted Approach to Ligament Balancing Using Kinetic Sensors.

BACKGROUND: Currently, soft-tissue imbalance contributes to several of the foremost reasons for revision following primary TKA, including instability, stiffness, and aseptic loosening. In order to decrease the incidence of soft-tissue imbalance, intraoperative sensors were developed to provide real-time, quantitative load data within the knee. This study examines the intraoperative data of a group of multicenter patients to determine how targeted ligament releases affect intra-articular loading, and to understand which types of releases are necessary to achieve quantified ligament balance. METHODS: A group of 129 patients received sensor-assisted TKA, as part of a multicenter study. Medial and lateral loading data were collected pre-release, during any sequential releases, and post-release. All data were collected at 10°, 45°, and 90° during range of motion testing. Ligament release type, release technique type, and resultant loading were collected. RESULTS: Loading across the joint decreased, overall, and became more symmetrical after releases were performed. On average, between 2 and 3 corrections were made (up to 8) in order to achieve ligament balance. The ligament release type and subsequent quantified change in loading were in agreement with historical, qualified sources. CONCLUSION: Objective data from sensor output may assist surgeons in decreasing loading variability and, thereby, decreasing ligament imbalance and its associated complications.

Primary TKA Patients with Quantifiably Balanced Soft-Tissue Achieve Significant Clinical Gains Sooner than Unbalanced Patients.

Although total knee arthroplasty has a high success rate, poor outcomes and early revision are associated with ligament imbalance. This multicenter evaluation was performed in order to provide 1-year followup of a previously reported group of patients who had sensor-assisted TKA, comparing the clinical outcomes of quantitatively balanced versus unbalanced patients. At 1 year, the balanced cohort scored 179.3 and 10.4 in KSS and WOMAC, respectively; the unbalanced cohort scored 156.1 and 17.9 in KSS and WOMAC (P < 0.001; P = 0.085). The average activity level scores of quantitatively balanced patients were 68.6 (corresponding to tennis, light jogging, and heavy yard work), while the average activity level of unbalanced patients was 46.7 (corresponding to light housework, and limited walking distances) (P = 0.015). Out of all confounding variables, a balanced articulation was the most significant contributing factor to improved postoperative outcomes (P < 0.001).

Use of jumbo cups for revision of acetabulae with large bony defects.

Several methods of treatment are available for acetabular revision associated with bone loss. Jumbo cups (minimum diameter of 62 mm in women, 66 mm in men, or 10 mm larger than the normal contralateral acetabulum) are often useful for large defects. The purpose of this study is to report a large jumbo cup series with an average 10-year follow-up. A total of 196 jumbo cups in 186 patients with a minimum of 2-year follow-up were available for review. Harris hip score improved from 44 preoperatively to 72 postoperatively. Survivorship was 98% at 4 years and 96% at 16 years. Five revisions and two resection arthroplasties were performed for failure. In conclusion, porous jumbo cup acetabular revision with supplemental screw fixation provides good to excellent intermediate- and long-term outcomes.

Knee strength retention and analgesia with continuous perineural fentanyl infusion after total knee replacement: randomized controlled trial.

PURPOSE: Despite providing adequate pain relief, a femoral nerve block can induce postoperative muscle weakness after total knee arthoplasty (TKA). Fentanyl has been shown to have peripheral effects but has not been used as a perineural infusate alone after TKA. METHODS: Sixty patients scheduled for TKA were randomized to one of three blinded groups: a continuous 24 h infusion of either fentanyl 3 µg/ml, ropivacaine 0.1%, or 0.9% normal saline through a femoral nerve sheath catheter at 10 ml/h. The main outcome was maximum voluntary isometric contraction (MVIC) in the quadriceps femoris (knee extension), measured by a handheld dynamometer (Nm/kg). Other variables assessed were preoperative and postoperative visual analog scale (VAS) scores, hamstrings MVIC (knee flexion), active range of motion of the operative knee, distance ambulated, incidence of knee buckling, supplemental morphine usage, postoperative side effects, and serum fentanyl levels. RESULTS: Quadriceps MVIC values were significantly greater in the fentanyl group compared to the group that received ropivacaine (median values, 0.08 vs. 0.03 Nm/kg; p = 0.028). The incidence of postoperative knee buckling upon ambulation was higher in the ropivacaine group compared to the fentanyl group, although not statistically significant (40% vs. 15 %, respectively; p = 0.077). VAS scores while ambulating were not significantly different between the fentanyl group and the ropivacaine group (p = 0.270). Postoperative morphine consumption, nausea and vomiting, and resting VAS scores were similar among the three groups. CONCLUSIONS: A continuous perineural infusion of fentanyl produced greater strength retention than ropivacaine post-TKA.

A new method for defining balance: promising short-term clinical outcomes of sensor-guided TKA.

Recently, technological advances have made it possible to quantify pounds of pressure across the bearing surface during TKA. This multicenter evaluation, using intraoperative sensors, was performed for two reasons: 1) to define "balance" 2) to determine if patients with balanced knees exhibit improved short-term clinical outcomes. Outcomes scores were compared between "balanced" and "unbalanced" patients. At 6-months, the balanced cohort scored 172.4 and 14.5 in KSS and WOMAC, respectively; the unbalanced cohort scored 145.3 and 23.8 in KSS and WOMAC (P < 0.001). Out of all confounding variables, balanced joints were the most significant contributing factor to improved postoperative outcomes (P < 0.001). Odds ratios demonstrate that balanced joints are 2.5, 1.3, and 1.8 times more likely to achieve meaningful improvement in KSS, WOMAC, and activity level, respectively.

Failure analysis of knee arthrodesis with the WichitaFusion Nail.

Arthrodesis is a salvage procedure for failed total knee arthroplasty with the intent to create a stable, pain-free limb on which to ambulate or transfer. For many patients, the alternative to arthrodesis may be an above-knee amputation. Available techniques for knee arthrodesis include compression plating, external fixators, and intramedullary fixation. The purpose of this study was to report the knee fusion rate of consecutive patients at 1 institution using an intramedullary fusion nail and to identify patient risk factors for fusion failure. Between November 1998 and November 2008, twenty-eight patients undergoing knee arthrodesis with an average follow-up of 18 months (range, 3-64 months) were retrospectively studied. Demographic information, presence of fusion, clinical function, pain level, and bone defect data were collected and analyzed. Eighty-two percent (23/28) of patients had radiographic evidence of successful fusion with an average time to fusion of 21 weeks (range, 10-58 weeks). When examining patient variables that could correlate with fusion rates, patients with an Anderson Orthopaedic Research Institute type 3 femoral or type 3 tibial defect had a statistically significant lower fusion rate. The intramedullary fusion nail is an effective device for knee arthrodesis that offers ease of insertion through the knee wound with the advantages of initial bone compression and rigid fixation. Although the use of intramedullary fusion nails leads to a high fusion rate, significant bone deficiency limits successful fusion.

Articulating spacers for the treatment of infected total knee arthroplasty: effect of antibiotic combinations and concentrations.

Performing 2-stage procedures using articulating antibiotic cement spacers to eradicate infection while providing pain relief and maintaining function has become common among many surgeons. Despite the efficacy of antibiotic cement spacers in the treatment of infected total knee arthroplasty, questions remain regarding the dosing of the antibiotic cement. The authors assessed their experience with different antibiotic regimens and concentrations for the eradication of infection. Sixty-nine infected total knee arthroplasties with an average follow up of 31 months (range, 6-70 months) treated with articulating antibiotic spacers were retrospectively reviewed. Treatment groups were divided according to spacer antibiotic agents used and the amount of antibiotics added to the cement. Low-dose spacers were defined as those incorporating less than 4 g of antibiotic per 40-g bag of cement, and high-dose spacers were defined as those incorporating 4 g or more of antibiotic per 40-g bag of cement. High- vs low-dose spacers using a single or multiple antibiotic agents were compared. The overall rate of infection eradication was 88%. Dose dependency was not detected for spacers that incorporated single or multiple antibiotic agents, and multiple-agent spacers produced comparable success rates despite more frequent use in patients with impaired immune function. Further study of optimal combinations and concentrations of antibiotic agents incorporated into these spacers is needed to help minimize treatment failures while maximizing treatment efficacy.

The Natural-Knee system: 25 years of successful results.

The Natural-Knee (NK) total knee arthroplasty (TKA) system has been in use for 25 years. The unique features of this system include a deep trochlear groove, an asymmetrical tibial baseplate, use of Cancellous-Structured Titanium coating for preferred bone ingrowth, and a bimetal cementless femoral component. So far, 3135 NK total knee replacements have been reviewed. Cementless femoral and tibial components were used in 22% of these cases, cementless femoral and cemented tibial components in 3%, and cemented femoral and tibial components in 75%. The revision rate was 1.6%. Only one revision was to correct uncomplicated aseptic loosening.

Surgical nuances to minimize muscle damage during the direct lateral approach in minimally invasive hip replacement.

Compared with total hip replacements performed using a standard incision direct lateral approach, a minimally invasive direct lateral approach can produce less pain and blood loss without increasing the rate of complications. To minimize the potential for limping after detaching the anterior gluteus medius and the gluteus minimus tendons, special handling of the abductors (which is more difficult because of the limited exposure afforded by the smaller incision) is required. Using special retractors, minimizing overzealous retraction, and achieving strong repair has resulted in no increase in the incidence of limping.

Total hip arthroplasty requiring subtrochanteric osteotomy for developmental hip dysplasia: 5- to 14-year results.

This study evaluated total hip arthroplasty in patients with developmental hip dysplasia requiring femoral subtrochanteric shortening derotational osteotomy (SDO). Twenty-three total hip arthroplasties that required SDO were evaluated at an average follow-up of 8 years (range, 5-14 years). Clinical and radiographic data were retrospectively reviewed. Four hips (17%) failed requiring revision. Time to revision averaged 4 years (range, 1-8 years) with polyethylene wear and osteolysis etiologic in 3 of 4 failures. Survivorship was 75% at 14 years. Subtrochanteric SDO provided reliable correction of dysplastic femoral deformity, facilitated hip reduction at the anatomic center, and demonstrated predictable union in all cases. Wear-induced osteolysis was the major reason for revision, probably due to the relatively thin polyethylene liners required for the small acetabular components used in young, active patients.

What would you do? Challenges in hip surgery.

The following are 5 case presentations of interesting and challenging patients with hip pathology.

Preoperative planning for revision total knee arthroplasty:avoiding chaos.

Use of preoperative planning is important in avoiding an unstable revision total knee arthroplasty. Physical examination should determine the status of the collateral ligaments so that implants with appropriate constraint are made available. Radiographic examination should determine if bone loss is present and whether primary or revision implants will be needed. Preoperative determination of the joint line position will simplify the surgery and facilitate flexion/extension space balancing. Three hundred sixty-five revision total knee arthroplasty surgeries were performed from 1987 to 2003. Of those, 82% were performed with unconstrained implants. Ten percent of the knees required varus/valgus constraint and 8% knees used rotating hinge components. Use of preoperative planning techniques resulted in postoperative stability in 99% of the revision total knee arthroplasties performed.

Cemented tibial stems are not requisite in revision.

Tibial stems are necessary in most total knee revisions to share the load and protect the fixation interface of the tibial tray. Successful use of a tibial stem requires independent stability of the stem with or without cement. Some additional geometry on the undersurface of the tibial tray such as peripheral pegs or fins is necessary to provide additional resistance to rotatory stresses if the stem is not cemented. Cementing the tibial stem works. However, with the excellent results of cementless stems, who would want to deal with cement removal in those few cases of loosening or the occasional case with infection or instability? The disadvantages of a press-fit stem are not seen with modem tibial stems, such as with a long conical stem with an offset attachment to the tibial baseplate as used in this series. Cement is not necessary!

Jumbo cup or high hip center: is bigger better?

A jumbo cup and a high hip center cup placement are 2 options in the revision of loose acetabular components associated with bone loss. They allow biologic attachment, which is required for long-term fixation. They are easier to use than cages. In my personal series of 564 acetabular revisions from 1986 to 2001, standard-size porous cups with a high hip center were used in 42 (7%) of the cases. Jumbo cups were used in 166 (29%) of the cases. Nineteen percent of the jumbo cups also were placed at a high hip center. The majority of these cups were placed into combined segmental and cavitary defects. The average follow-up was 6.1 years. One jumbo cup and 1 high hip center standard cup were revised for aseptic loosening (1%). The 5-year and 10-year survival rates for shell revision were 95% and 87%, respectively.