Patient specific instrumentation.

Patient specific instrumentation (PSI) has recently been developed as a replacement for traditional instrumentation in total knee arthroplasty (TKA). The study aim was to assess efficiency via the mean total OR time using the PSI versus computer-assisted (CAS) TKAs with accuracy as a secondary endpoint. Sixty patients were randomized to CAS or PSI. A formula was developed to derive a profit ratio (PR) that incorporated costs, revenue, and total OR time. The PSI cases were 1.45 times more profitable than CAS allowing for approximately 3 PSI cases versus 2 CAS cases in one 8 hour OR day. Results from this series show that PSI improves OR efficiency, but does not improve accuracy.

Protection of repaired patellar tendons a surgical technique.

Patellar tendon avulsion repairs are a frequent necessity in knee arthroplasty and revisions. These repairs are often accompanied by compromised healing from previous surgeries, resulting in devitalization of tissues and vascular support with scar tissue formation. This study describes the use of a dynamic and flexible leash to limit excursion of the patella while protecting the fragile repair.

A comparison of wound closure techniques for total knee arthroplasty.

Four wound closure techniques for total knee arthroplasty were compared in a prospective, randomized, controlled, institutional review board-approved study with 75 subjects. The study compared tissue adhesives, stapling, and suturing with respect to procedure time and cost, together with functional and clinical outcome. Total knee arthroplasty closure time (capsule to cutaneous) favored staples at 26 s/cm, followed by adhesives (45 and 37 s/cm for 2-octyl and n-butyl-2, respectively) and, finally, subcuticular suturing at 54 s/cm (P < .0007). Reduced procedure time translated into intraoperative cost reduction where closure cost per centimeter was $70, $62, $57, and $75 for 2-octyl, n-butyl-2, staples, and sutures, respectively. No significant differences in infection, dehiscence, cosmesis, general health (SF-12v2 (QualityMetric Inc., Lincoln, RI)), and functional and clinical assessments (range of motion, Knee Society knee score, and pain) were observed.

Minimizing electromagnetic interference from surgical instruments on electromagnetic surgical navigation.

BACKGROUND: Electromagnetic computer-assisted surgery (EM-CAS) can be affected by various metallic or ferromagnetic factors. QUESTIONS/PURPOSES: We determined to what extent metals interfere with accuracy and identified measures to prevent interference from occurring. METHODS: Using an EM-CAS system, we made six standard measurements of tibiofemoral position and alignment on a surrogate knee. A stainless steel mallet was positioned 10 cm from the stylus, and then 10 cm from the localizer to create errors attributable to electromagnetic interference. The experiment was repeated with bars of different metals placed 10 cm from the stylus. RESULTS: The maximum errors recorded with a mallet were: varus/valgus alignment, -2.7 degrees and 2.4 degrees; flexion/extension, -5.8 degrees and 3.0 degrees; lateral resection level, -3.1 and 7.5 mm; and medial resection level, -4.0 and 2.3 mm, respectively. The smallest errors were recorded with cylinders of titanium, cobalt-chrome alloy, and stainless steels. When moved more than 10 cm away from the stylus, errors became negligible. CONCLUSIONS: The accuracy of EM navigation systems is affected substantially by the size, type, proximity, and shape of metal objects. CLINICAL RELEVANCE: Stainless steel objects, such as cutting blocks and trial prostheses, should be kept more than 10 cm from EM-CAS instruments to minimize error.

Periprosthetic Fracture of Greater Trochanter in Total Hip Replacement Stemming from Pin Site Placement in Navigation-Assisted Surgery.

Surgeons are looking to use computer computer-assisted surgery (CAS) in total hip arthroplasty (THA) in order to quantify leg length measurement, angular cup placement, and enhance stability to provide enhanced accuracy in implant placement. As a result, CAS in THA is gaining popularity. This technology employs the use of pins and provides the surgeon with real-time feedback on positioning intraoperatively. Previous total knee arthroplasty (TKA) literature has reported pin-associated complications such as infections, neuropraxia, and suture abscess. To our knowledge, there have been reports of tibial stress fracture after CAS TKA, but this is the first report of a pin causing fracture of the greater trochanter leading to dislocation in THA. Further studies may be warranted to optimize pin placement for trackers to prevent fractures of the greater trochanter.

What role does metal allergy sensitization play in total knee arthroplasty revision?

BACKGROUND: Clinicians are often faced with the decision whether to revise a painful total knee replacement in patients who have chronic vague pain with no apparent explanation. A sensitive metal testing assay called the lymphocyte stimulation test has been used to detect nickel sensitization in patients with orthopedic implants. We hypothesize that nickel sensitization plays a role in the pathology of failed joint arthroplasty in patients with unexplained dissatisfaction. METHODS: 32 patients with symptomatic total knee arthroplasty without obvious mechanical findings were tested prior to revision surgery. 19 nickel-sensitized and 13 non-sensitized patients were compared by cell counts of synovium surgical specimens for CD4+ and CD8+ cell lines. Patients were then revised with ceramic-coated implants. Secondary evaluation of functional outcomes, range of motion, and pain relief were assessed. RESULTS: Nickel-sensitive patients showed a statistical increase in CD4+ reactivity compared to CD8+ reactivity. The ratio of CD4+/CD8+ T lymphocytes was 1.28 in nickel-sensitive patients versus 0.76 in the control (p = 0.009). There was no difference in functional scores, clinical scores, or range of motion after revision. CONCLUSIONS: This study provides objective data via histological analysis in support of a nickel allergic sensitization in failed arthroplasties where clinical and/or radiographic abnormalities may not be apparent. Biopsy for CD4+/CD8+ cell counts may provide further proof of the existence of nickel sensitization in lymphocyte stimulation test positive patients, and more importantly, may implore the surgeon to consider low nickel implant design in these patients.

Pregabalin for the treatment of postoperative pain: results from three controlled trials using different surgical models.

PURPOSE: To evaluate the efficacy and safety of pregabalin (150 or 300 mg/d) as an adjunctive therapy for the treatment of postoperative pain. PATIENTS AND METHODS: This study reports findings from three separate, multicenter, randomized, double-blind, placebo-controlled trials of adjunctive pregabalin for the treatment of postoperative pain. Patients underwent one of three categories of surgical procedures (one procedure per study): elective inguinal hernia repair (post-IHR); elective total knee arthroplasty (post-TKA); or total abdominal hysterectomy (posthysterectomy). The primary endpoint in each trial, mean worst pain over the past 24 hours, was assessed 24 hours post-IHR and posthysterectomy, and 48 hours post-TKA. Patients rated their pain on a scale from 0 to 10, with higher scores indicating greater pain severity. RESULTS: In total, 425 (post-IHR), 307 (post-TKA), and 501 (posthysterectomy) patients were randomized to treatment. There were no statistically significant differences between the pregabalin and placebo groups with respect to the primary endpoint in any of the three trials. The least squares mean difference in worst pain, between 300 mg/d pregabalin and placebo, was -0.7 (95% confidence interval [CI] =-1.4, -0.1; Hochberg adjusted P=0.067) post-IHR; -0.34 (95% CI =-1.07, 0.39; P=0.362) post-TKA; and -0.2 (95% CI =-0.66, 0.31; P=0.471) posthysterectomy. CONCLUSION: There were no significant differences between pregabalin and placebo with respect to the primary pain intensity measure in each of the three clinical trials. These studies encompass a large dataset (1,233 patients in total), and their results should be considered when assessing pregabalin's effectiveness in postoperative pain. Further studies are required to determine the potential pain-reducing benefit of pregabalin in the postoperative setting.

Assessing whether preoperative templates and planning can replace intraoperative computer-assisted surgery measurements in total knee arthroplasty.

It is incumbent on the orthopedic community to assess current technologies available to predict the size of implants used for total knee arthroplasty (TKA) and whether they can accurately represent what will be visualized by surgeons intraoperatively. This study highlights the traditional practice of TKA by applying digitization software to streamline existing knowledge preoperatively in an effort to more accurately dimension the implants. The primary goal of the study was to assess the predictive value of a digitized templating system for TKA. The secondary goal was to ascertain whether varus, valgus, and flexion deformities were accurately predicted to intraoperative measures using computer-assisted surgery. Forty-three patients were prospectively assessed using standard-of-care 36-inch anteroposterior evaluations for determining mechanical angle and flexion contractures. Simultaneously, traditional radiographs were used as a sizing tool for the digitized software program. Statistical evaluation was completed by 2-tailed t test with incorporation of a varied window of acceptance (± 3° and ± 2° in mechanical angle and flexion contracture measurements, respectively). This study showed a poor correlation between the predictive value of the digitization software; just one-third of the cases were accurately predicted.

Is computer-assisted surgery in total knee arthroplasty as accurate as it can be?

Three hundred and eighty computer-assisted total knee arthroplasty cases were reviewed for accuracy of mechanical alignment. The 331 patients in the first set, designated Group A, showed a consistent valgus error of 1° from neutral alignment. It was hypothesized that a manual 1° varus correction during femur resection would yield a significantly greater level of accuracy in the second set of 49 patients, designated Group B. A mechanical alignment of ±3° was achieved in 91% of the uncalibrated Group A patients, which was significantly lower (p = 0.035) than the rate of 98% achieved in the calibrated Group B. Further statistical analysis of the data showed the time expenditure was not significantly changed once a new target value was recalibrated. By quantifying mean errors of measures at an early timeframe, enhanced accuracy in CAS can be achieved.

Improved knee flexion following high-flexion total knee arthroplasty.

BACKGROUND: The application of new techniques and materials in total knee arthroplasty (TKA) continue to be a primary focus in orthopedic surgery. The primary aim of the present study is to evaluate post TKA total range of motion (ROM) among a group of patients who received a gender specific high-flexion design modification implant compared to a control group of patients who received non-gender specific implants. METHODS AND RESULTS: The control group was comprised of 39 TKAs that were recruited pre-operatively and received the non-gender specific implant while the study group consisted of 39 TKAs who received gender specific implants. The study group yielded an improvement in mean post-operative ROM of 21° at 12 months, whereas the mean improvement in ROM among the control group was 11°. Thus, the study group had a 10° increased ROM improvement (91%) over the control group (p = 0.00060). In addition, 100% of the subjects with gender specific high-flexion implants achieved greater or equal ROM post-operatively compared to 82% for the control cohort. Lastly, women who exhibited greater pre-operative ROM and lower body mass index (BMI) were found to benefit the most with the gender specific prosthesis. CONCLUSION: Our study demonstrates that among subjects with a normal BMI, the gender specific high-flexion knee implant is associated with increased ROM as compared to the non-gender specific non-high-flexion implant designs.

Diclofenac epolamine topical patch relieves pain associated with ankle sprain.

BACKGROUND: Sports-related injuries, such as sprains and strains, commonly occur during exercise and athletic events. Current therapy includes nonsteroidal anti-inflammatory drugs (NSAIDs), which have a high incidence of upper gastrointestinal side effects. The present study assessed the efficacy and safety of the diclofenac epolamine topical patch (DETP, 1.3%), a topical NSAID for the treatment of acute minor sprains and strains. METHODS: This multicenter, randomized, placebo-controlled clinical study enrolled adult patients (n = 134) with acute ankle pain (due to a minor sprain) occurring less than 48 hours prior to entering the study. Patients were treated with either the DETP or a placebo topical patch daily for seven days. Pain intensity was evaluated during the first six hours after application of the patch, and on treatment days 1, 2, 3, and 7. RESULTS: Patients treated with the DETP experienced a significantly greater reduction in pain associated with their ankle injury compared with placebo, beginning four hours after the first patch application (P = 0.02). The DETP was well tolerated and was comparable with placebo in terms of safety. CONCLUSION: Overall, the results of this study demonstrate that the DETP is an effective analgesic for local treatment of pain in mild acute ankle sprain.

Pooled analysis of clinical trial data evaluating the safety and effectiveness of diclofenac epolamine topical patch 1.3% for the treatment of acute ankle sprain.

This pooled analysis assessed the efficacy and safety of the diclofenac epolamine topical patch 1.3% (DETP) for the treatment of acute mild-to-moderate ankle sprain. Data from 2 randomized, double-blind, placebo-controlled studies enrolling 274 male and female patients aged 18 to 65 years with acute ankle sprain were pooled and evaluated. The primary end point was pain reduction on movement assessed using a 100 mm visual analog scale (VAS). Safety and tolerability were also assessed. Beginning approximately 3 hours after initial treatment, DETP-treated patients experienced statistically significant and sustained lower mean VAS scores in pain intensity on movement (mean ± SD, 54.1 ± 20.0 mm versus 60.3 ± 16.8 mm) compared with placebo-treated patients, representing a 20% versus 13% reduction in VA S pain scores from baseline (P = 0.012). This statistically significant difference in mean VAS score was maintained through day 7 (9.4 ± 14.4 mm versus 18.4 ± 18.2 mm, P < 0.0001). The DETP and placebo patches were well tolerated. These results further confirm the efficacy and safety of DETP for the treatment of acute pain from ankle sprains.

Topical nonsteroidal anti-inflammatory drugs for the treatment of pain due to soft tissue injury: diclofenac epolamine topical patch.

The objective of this article is to review published clinical data on diclofenac epolamine topical patch 1.3% (DETP) in the treatment of acute soft tissue injuries, such as strains, sprains, and contusions. Review of published literature on topical nonsteroidal anti-inflammatory drugs (NSAIDs), diclofenac, and DETP in patients with acute soft tissue injuries was included. Relevant literature was identified on MEDLINE using the search terms topical NSAIDs, diclofenac, diclofenac epolamine, acute pain, sports injury, soft tissue injury, strain, sprain, and contusion, and from citations in retrieved articles covering the years 1978-2008. Review of published, randomized clinical trials and meta-analyses shows that topical NSAIDs are significantly more effective than placebo in relieving acute pain; the pooled average relative benefit was 1.7 (95% confidence interval, 1.5-1.9). In a limited number of comparisons, topical and oral NSAIDs provided comparable pain relief, but the use of topical agents produced lower plasma drug concentrations and fewer systemic adverse events (AEs). The physical-chemical properties of diclofenac epolamine make it well suited for topical use. In patients with acute soft tissue injuries treated with DETP, clinical data report an analgesic benefit within hours of the first application, and significant pain relief relative to placebo within 3 days. Moreover, DETP displayed tolerability comparable with placebo; the most common AEs were pruritus and other application site reactions. Review of published literature suggests that DETP is generally safe and well tolerated, clinically efficacious, and a rational treatment option for patients experiencing acute pain associated with strains, sprains, and contusions, and other localized painful conditions.

Relationship between patient-reported disease severity in osteoarthritis and self-reported pain, function and work productivity.

INTRODUCTION: Understanding the relationship between patient-reported osteoarthritis (OA) severity and other patient-reported outcomes in the real-world clinical setting can provide a basis for appropriate patient management. The objective of this study was to determine how patient-reported OA severity correlates with patient-reported outcomes including pain, function and productivity. METHODS: We used the Adelphi Disease Specific Programme (DSP) for OA, a database aggregated from large, multinational, observational studies for specific chronic diseases. Data were obtained based on a 0 to 100 mm pain visual analogue scale (VAS) and a series of questions including functioning (that is, activities of daily living) and work productivity. OA severity was rated by the patients based on the question "How bad would you say your arthritis is now?" with potential responses of "mild," "moderate," and "severe." Regression models and chi-square analyses were used to evaluate the relationships between self-reported OA severity and other outcomes. RESULTS: Of 998 subjects in the OA DSP U.S. database, 714 (72.5%) agreed to participate. This sample was predominantly female (61.7%) with a mean age of 63.8 ± 12.9 years. Increased OA severity was associated with an older population (P < 0.05). With increasing OA severity (mild, moderate, severe), statistically significant differences (P < 0.05) were observed in increased pain VAS scores (23.5, 50.2, 70.8, respectively), lower functioning outcomes, and a higher percent of overall work impairment due to OA (17%, 37%, 48%, respectively). The increased work impairment at greater severity levels also resulted in higher costs related to lost work productivity, with annual costs due to lost productivity estimated at $6,096, $13,2510, and $17,214 per patient for self-reported mild, moderate, and severe OA, respectively (P < 0.05 for pairwise comparisons). CONCLUSIONS: In the clinical practice setting, patient-reported OA severity was associated with other key patient-reported outcomes and thus may provide an accurate and tangible assessment of patients' perceptions of their disease. Identifying OA patients by their perceived severity level may be of benefit to patients and health-care providers when choosing treatment options aimed at reducing pain, and improving function and productivity.

How does electromagnetic navigation stack up against infrared navigation in minimally invasive total knee arthroplasties?

Forty-six primary total knee arthroplasties were performed using either an electromagnetic (EM) or infrared (IR) navigation system. In this IRB-approved study, patients were evaluated clinically and for accuracy using spiral computed tomographic imaging and 36-in standing radiographs. Although EM navigation was subject to metal interference, it was not as drastic as line-of-sight interference with IR navigation. Mechanical alignment was ideal in 92.9% of EM and 90.0% of IR cases based on spiral computed tomographic imaging and 100% of EM and 95% of IR cases based on x-ray. Individual measurements of component varus/valgus and sagittal measurements showed EM to be equivalent to IR, with both systems producing subdegree accuracy in 95% of the readings.

Celecoxib does not affect osteointegration of cementless total hip stems.

Celecoxib's effect on prosthetic osteointegration in patients undergoing total hip arthroplasty was studied. In a prospective, placebo-controlled, double-blind study of 49 patients, 24 were randomized to celecoxib (200 mg/d) and 25 to placebo over 6 weeks. Bone markers, N-teleopeptide, and bone-specific alkaline phosphatase were obtained postoperatively, and at 6 and 12 weeks. No radiographic prosthetic subsidence occurred. There were no significant differences from baseline in periprosthetic bone mineral density between the celecoxib and placebo groups at 3 and 6 months. There were no significant differences in baseline BSAlkP values between the 2 groups. At 6 and 12 weeks, average BSAlkP values increased. Urinary NTx concentrations followed a skewed distribution. Normalized NTx concentrations were statistically significantly greater in the celecoxib group than the placebo group at 6 weeks but not at 12 weeks.