Randomized Controlled Trial of Posterior Lumbar Interbody Fusion With Ti- and CaP-Nanocoated Polyetheretherketone Cages: Comparative Study of the 1-Year Radiological and Clinical Outcome.

BACKGROUND: Polyetheretherketone (PEEK) is a popular material for posterior lumbar interbody fusion (PLIF) cages, although osseointegration remains limited. To optimize PEEK cage characteristics, titanium (Ti) and calcium phosphate (CaP) nanocoatings have been developed with proven mechanical safety. This multicenter randomized controlled trial compared the clinical and radiological outcome parameters of nanocoated and uncoated PEEK cages, up to 1 year after surgery. METHODS: Standard open PLIF surgery was performed on 127 patients, randomized in 3 groups: Ti-nanocoated (n = 44), CaP-nanocoated (n = 46), and uncoated PEEK cages (n = 37). Clinical assessments up to 1 year after surgery included visual analogue scales (VASs), Oswestry Disability Index (ODI), and 36-Item Short Form Survey (SF-36). Primary radiological outcome parameters were implant stability and fusion status, assessed by x-ray and computed tomography (CT) scans. Patients, surgeons, and postsurgery analysts were blinded. RESULTS: PLIF surgery with all cage types resulted in significant improvements of clinical outcome parameters, exceeding the minimum clinically important differences. No significant differences in VAS, ODI, or SF-36 scores were found among the 3 groups. One year after the surgery, 65.6% of patients with uncoated PEEK cages achieved definite fusion. Significantly more patients with nanocoated PEEK cages achieved definite fusion: 93.9% for Ti nanocoating (P = .0034) and 88.0% for CaP nanocoating (P = .032). No significant differences in fusion were found between the nanocoated cage types (P = .4318). CONCLUSIONS: The similar clinical outcome improvements after 1 year suggest that nanocoated PEEK cages have the same safety and efficacy as the clinically accepted uncoated PEEK cages. Furthermore, nanocoated PEEK cages achieved a better fusion rate than uncoated PEEK cages at the 1-year follow-up. A 5-year follow-up study is warranted to revisit the findings. CLINICAL RELEVANCE: The safety, efficacy, and enhanced osseointegration of nanocoated PEEK cages were demonstrated. Osseointegration is a significant predictor of positive long-term clinical outcomes and improved implant longevity, implying a clinical added value of nanocoatings. Enhanced osseointegration becomes even more important in minimally invasive spine surgery and in patients at risk for incomplete fusion.

Resistance of coated polyetheretherketone lumbar interbody fusion cages against abrasion under simulated impaction into the disc space.

In order to improve osseointegration, polyetheretherketone (PEEK) interbody fusion cages are frequently surface coated. The bonding strength of the coatings is mostly investigated under unrealistic loading conditions. To close this gap, in this study, uncoated and coated cages were loaded in a clinical setup in order to investigate their real resistance against abrasion. Six uncoated, six calcium phosphate (CaP) nanocoated, and six titanium (Ti) nanocoated PEEK cages were tested in this study. The experimental setup was designed to mimic cage impaction into the intervertebral disc space using polyurethane (PU) foam blocks as vertebral body substitutes. The cage surface was inspected before and after impaction, and their weight was measured. Impaction resulted in abrasion at the tip of the ridges on the implant surface. The mean weight loss was 0.39 mg for the uncoated cages, 0.57 mg for the CaP nanocoated cages, and 0.75 mg for the Ti nanocoated cages. These differences were statistically significant. In conclusion, differences between the three cage types were found concerning the amount of abrasion. However, all three cages lost less weight than a comparative Ti plasma spray coated cage, which showed a mean weight loss of 2.02 mg. This may be because the plasma spray coating is significantly thicker than the two nanocoatings. If compared with the permitted amount of weight loss derived from an FDA guidance document, which is approximately 1.7 mg, the wear of the Ti plasma spray coated cage is above this limit, whereas the wear for all other cage types is below.

The M6-C Cervical Disk Prosthesis: First Clinical Experience in 33 Patients.

STUDY DESIGN: Retrospective study. OBJECTIVE: To determine the short-term clinical succesrate of the M6-C cervical disk prosthesis in primary and secondary surgery. SUMMARY OF BACKGROUND DATA: Cervical disk arthroplasty (CDA) provides an alternative to anterior cervical decompression and fusion for the treatment of spondylotic radiculopathy or myelopathy. The prevention of adjacent segment disease (ASD), a possible complication of anterior cervical decompression and fusion, is its most cited--although unproven--benefit. Unlike older arthroplasty devices that rely on a ball-and-socket-type design, the M6-C cervical disk prosthesis represents a new generation of unconstrained implants, developed to achieve better restoration of natural segmental biomechanics. This device should therefore optimize clinical performance of CDA and reduce ASD. MATERIALS AND METHODS: All patients had preoperative computed tomography or magnetic resonance imaging and postoperative x-rays. Clinical outcome was assessed using the Neck Disability Index, a Visual Analog Scale, and the SF-36 questionnaire. Patients were asked about overall satisfaction and whether they would have the surgery again. RESULTS: Thirty-three patients were evaluated 17.1 months after surgery, on average. Nine patients had a history of cervical interventions. Results for Neck Disability Index, Visual Analog Scale, and SF-36 were significantly better among patients who had undergone primary surgery. In this group, 87.5% of patients reported a good or excellent result and 91.7% would have the procedure again. In contrast, all 4 device-related complications occurred in the small group of patients who had secondary surgery. CONCLUSIONS: The M6-C prosthesis appears to be a valuable addition to the CDA armatorium. It generates very good results in patients undergoing primary surgery, although its use in secondary surgery should be avoided. Longer follow-up is needed to determine to what measure this device can prevent ASD.

Fine grained osseointegrative coating improves biocompatibility of PEEK in heterotopic sheep model.

BACKGROUND AND AIM: Polyetheretherketone (PEEK) materials already have been used successfully in orthopedic and especially spine surgery. PEEK is radiolucent and comparable with bone regarding elasticity. However, PEEK is inert and the adhesion of PEEK implants to bone tissue proceeds slowly because of their relatively low biocompatibility. The aim of the study is to evaluate the effect of titanium and CaP coating on the adhesion of bone tissue. MATERIAL AND METHODS: Six adult sheep (body weight 57.6 ± 3.9 kg) were included in this study. Three different types of cylindrical dowels (12 mm length x 8 mm diameter) were implanted in long bones (tibia and femur): PEEK dowels without coating (the control group), and PEEK dowels with a nanocoating of calcium phosphate (CaP group) or titanium (titanium group). Animals were sacrificed after 6, 12 and 26 weeks. Dowels were explanted for micro CT and histology. RESULTS: Bone implant contact (BIC) ratio was significantly higher in the titanium versus control groups in the 6 to 12 weeks period (p = 0.03). The ratio between bone volume and tissue volume (BV/TV) was significantly higher in titanium versus control in the 6 to 12 weeks period (p = 0.02). A significant correlation between BIC and BV/TV was seen (r = 0.85, p < 0.05). CONCLUSION: Coating of PEEK dowels with a nanocoating of titanium has beneficial effects on adhesion of bone tissue.

Arthroscopic release of suprascapular nerve entrapment at the suprascapular notch: technique and preliminary results.

PURPOSE: We describe a novel all-arthroscopic technique for suprascapular nerve (SSN) decompression and present our preliminary results for this procedure. METHODS: A prospective series of 10 patients with preoperative electromyographic findings consistent with chronic SSN compression, posterior shoulder pain, and subjective weakness were treated with arthroscopic SSN decompression. There were 8 men and 2 women, with a mean age of 50 years. The mean follow-up was 15 months (range, 6 to 27 months). In 8 of 10 patients, we performed an electromyographic examination postoperatively to evaluate nerve recovery after decompression. The clinical outcomes measures used to assess preoperative and postoperative function were the visual analog scale for pain, the Constant score, strength testing of the supraspinatus and infraspinatus, and a subjective satisfaction questionnaire. In all patients preoperative and postoperative computed tomography arthrograms were obtained to document the absence of a rotator cuff tear. RESULTS: There were no complications resulting from SSN decompression. Of 10 patients, 8 had postoperative electromyography at a mean of 6 months after SSN release and 2 refused to undergo this study after surgery. Of the 8 postoperative electromyograms, 7 had complete normalization of the latency in the motor fibers of the SSN and normalization of the voluntary motor action potential for the supraspinatus and infraspinatus muscles. Two of the electromyograms showed evidence of partial recovery. The preoperative and postoperative Constant scores for these patients were 60.3 and 83.4, respectively (P < .001). All patients returned to their normal work and sports activity at a mean of 3 weeks (range, 2 days to 3 months). The abduction and external rotation strength also significantly improved. At the time of last follow-up, 9 patients graded their clinical outcome as excellent and responded that they had complete relief of pain. One of the study subjects reported a satisfactory result with moderate relief of pain. CONCLUSIONS: Arthroscopic release of the SSN can be performed safely and effectively. All of the patients in this preliminary study had improvement in their postoperative electromyographic findings and had marked improvement in pain relief and function. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Spinal osteotomy in patients with ankylosing spondylitis: complications during first postoperative year.

STUDY DESIGN: A historic cohort to determine short-term complications after 115 corrective osteotomies of the cervical and lumbar spine in patients with ankylosing spondylitis. OBJECTIVES: To describe the nature of complications of spinal osteotomies and sequelae. SUMMARY OF BACKGROUND DATA: Little is known about the rate and nature of complications after spinal osteotomy in these patients. METHODS: A chart review of 106 patients (age, 21-82 years) was conducted. The following surgical techniques were performed: cervical-thoracic extending osteotomy at C6-Th1 (n = 22), lumbar closing-wedge osteotomy (n = 62), polysegmental lumbar osteotomy (n = 20), or a combined anterior-posterior lumbar correction (n = 11). RESULTS: Many complications (7.8% permanent neurologic deficit, 9.6% deep wound infections, and 10.4% major general complications) occurred after performing a spinal correction. Since 1998, there is a tendency for a lower rate of infections but a higher rate of neurologic and major general complications. Because of 27% deep wound infections and 18% major general complications, the technique of combined anterior and posterior surgery has been abandoned. CONCLUSION: High complication rates in this group of patients are partly due to the difficult surgery but also to the underlying disease. The surgery should be concentrated in specialized centers.

Tricalcium phosphate granules or rigid wedge preforms in open wedge high tibial osteotomy: a radiological study with a new evaluation system.

The capacity of two forms of porous beta-tricalcium phosphate bone substitutes (TCP) to promote bone healing in open wedge high tibial osteotomy (OWHTO) was studied. We reviewed the X-rays of 27 osteotomies, with either TCP wedges or TCP granules as filling material, to compare the bone healing rates and bone remodelling, at specific postoperative intervals. A new radiologic rating system for OWHTO was created and tested for clinical applicability. All osteotomies healed uneventfully and complete resorption of TCP was demonstrated at 1 year postoperative in 85% (n = 23) of the procedures. In 44% (n = 10) of these 23 procedures, the osteotomy site was no longer visible. No difference in bone healing rate and bone remodelling was found when comparing the use of granules to a wedge, and no adverse effects of TCP were observed. The good inter- (k = 0.7) and intraobserver (k = 0.6) reliability of the new radiologic rating system enables clinical use. Good bone healing was found in OWHTO with both wedges and granules of TCP.

The Kudo total elbow arthroplasty in patients with rheumatoid arthritis.

A Kudo total elbow arthroplasty (TEA) was performed in 36 elbows in 35 patients with rheumatoid arthritis. Of those 35, 4 died, 6 prostheses were revised, and 2 were lost to follow-up. Twenty-four elbows with a mean follow-up of 58 months were radiologically and clinically reviewed. Sixteen were scored as excellent by use of the Mayo score and Hospital for Special Surgery 2 score. The mean increase in active motion was 25 degrees. Two humeral and four ulnar radiologic loosenings were noted. Two early dislocations were successfully treated with closed reduction and cast immobilization, two patients used an elbow brace after the closed reduction, and one patient underwent a resection arthroplasty for instability and deep wound infection. Four aseptic loosenings, of which three had an intraoperative fracture at the index operation and one had instability, were revised. Despite initially excellent results, longer follow-up of TEA in rheumatoid patients demonstrated deterioration of the outcome and increased loosening.