Lumbar spinal stenosis - surgical outcome and the odds of revision-surgery: Is it all due to the surgeon?

BACKGROUND: Surgical decompression is the intervention of choice for lumbar spinal stenosis (LSS) when non-operative treatment has failed. Apart from acute complications such as hematoma and infections, same-level recurrent lumbar stenosis and adjacent-segment disease (ASD) are factors that can occur after index lumbar spine surgery. OBJECTIVE: The aim of this retrospective case series was to evaluate the outcome of surgery and the odds of necessary revisions. METHODS: Patients who had undergone either decompressive lumbar laminotomy or laminotomy and spinal fusion due to lumbar spinal stenosis (LSS) between 2000 and 2011 were included in this analysis. Demographic, perioperative and radiographic data were collected. Clinical outcome was evaluated using numeric rating scale (NRS), the symptom subscale of the adapted version of the german Spinal Stenosis Measure (SSM) and patient-sreported ability to walk. RESULTS: Within the LSS- cohort of 438 patients, 338 patients underwent decompression surgery only, while instrumentation in addition to decompression was performed in 100 cases (22.3%). 38 patients had prior spinal operations (decompression, disc herniation, fusion) either at our hospital or elsewhere. Thirty-five intraoperative complications were documented with dural tear with CSF leak being the most common (33/35; 94.3%). Postoperative complications were defined as complications that needed surgery and differentiated between immediate postoperative complications (⩽ 3 weeks post operation) and complications that needed revisions surgery at a later date. Within all patients 51 revisions were classified as immediate complications of the index operation with infections, neurological deficits and hematoma being the most common. Within this group only 22 patients had fusion surgery in the first place, while 29 were treated by decompression. Revision surgery was indicated by 53 patients at a later date. While 4 patients decided against surgery, 49 revision surgeries were planned. 28 were performed at the same level, 10 at the same level plus an adjacent level, and 10 were executed at index level with indications of adjacent level spinal stenosis, adjacent level spinal stenosis plus instability and stand-alone instability. Pre- operative VAS score and ability to walk improved significantly in all patients. CONCLUSIONS: While looking for predictors of revision surgery due to re-stenosis, instability or same/adjacent segment disease none of these were found. Within our cohort no significant differences concerning demographic, peri-operative and radiographic data of patients with or without revision wer noted. Patients, who needed revision surgery were older but slightly healthier while more likely to be male and smoking. Surprisingly, significant differences were noted regarding the distribution of intraoperative and early postoperative complications among the 6 main surgeons while these weren't obious within the intial index group of late revisions.

The effect of autologous Achilles bursal tissue implants in tendon-to-bone healing of rotator cuff tears in rats.

BACKGROUND: The aim of this study was to investigate the influence of autologous bursal tissue derived from the Achilles bursa on tendon-to-bone healing after rotator cuff tear repair in a rat model. METHODS: A total of 136 Sprague-Dawley rats were randomly assigned to either an untreated or a bursal tissue application group or biomechanical testing and histologic testing after rotator cuff repair. After separating the supraspinatus tendon close to the greater tuberosity, the tendon was reattached either unaltered or with a bursal tissue interposition sewn onto the interface. Immunohistologic analysis was performed 1 and 7 weeks after supraspinatus tendon reinsertion. Biomechanical testing of the tendon occurred 6 and 7 weeks after reinsertion. RESULTS: Immunohistologic results demonstrated a significantly higher percentage of Type II collagen (P = .04) after 1 and 7 weeks in the tendon-to-bone interface using autologous bursal tissue in comparison to control specimens. The bursa group showed a significantly higher collagen I to III quotient (P = .03) at 1 week after surgery in comparison to the 7-week postsurgery bursa groups and controls. Biomechanical assessment showed that overall tendon stiffness (P = .002) and the tendon viscoelasticity in the bursa group (P = .003) was significantly improved after 6 and 7 weeks. There was no significant difference (P = .55) in force to failure between the bursa group and the control group after 6 and 7 weeks. CONCLUSION: Autologous bursal tissue derived from the Achilles bursa and implanted to the tendon-to-bone interface after rotator cuff repair facilitates a faster healing response to re-establish the biologic and biomechanical integrity of the rotator cuff in rats.

Patient-Reported and Magnetic Resonance Imaging Outcomes of Third-Generation Autologous Chondrocyte Implantation After 10 Years.

PURPOSE: To evaluate the long-term clinical and radiologic outcomes of third-generation autologous chondrocyte implantation (ACI) for the treatment of focal cartilage defects of the knee. METHODS: Data capture was carried out between 2004 and 2018. Included were patients with cartilage defects of the knee joint with an International Cartilage Repair Society grade of III or higher treated with third-generation ACI who had a minimum follow-up period of 10 years. International Knee Documentation Committee scores and assessment of pain at rest and on movement using visual analog scale scores were captured preoperatively and at 6 months postoperatively, as well as annually thereafter. In addition, we performed magnetic resonance imaging examinations in 13 cases after 10 years. The MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score was used to evaluate the ACI cartilage. RESULTS: A total of 54 patients met the inclusion criteria. Of these, 30 reached the 10-year follow-up point and were included in this assessment. At 10 years postoperatively, all clinical outcome parameters showed a statistically significant improvement compared with the preoperative situation, with a responder rate of 70%. The average MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score after 10 years was 59.2 points (range, 20-100 points), and over 60% of the evaluated patients showed good integration of the implant at 10 years postoperatively. CONCLUSIONS: The clinical and radiologic findings of this study show that third-generation ACI is a suitable and effective option in the treatment of full-thickness cartilage defects of the knee. At 10 years after surgery, third-generation ACI shows stable results and leads to significant improvement in all clinical outcome parameters. Despite these results, revision surgery after third-generation ACI is common and was needed in 23% of patients in this study. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Rotator Cuff Repair With Autologous Tenocytes and Biodegradable Collagen Scaffold: A Histological and Biomechanical Study in Sheep.

BACKGROUND: Large rotator cuff tears still represent a challenging problem in orthopaedics. The use of tenocytes on biomaterials/scaffolds for the repair of large rotator cuff defects might be a promising approach in the field of tendon regeneration. HYPOTHESIS: Cultivated autologous tenocytes seeded on a collagen scaffold lead to enhanced histological and biomechanical results after rotator cuff repair in a sheep model as compared with unseeded scaffolds in an acute setting. STUDY DESIGN: Controlled laboratory study. METHODS: At the tendon-bone junction of the infraspinatus tendon of the right foreleg of 24 sheep, a 3.5 × 1.5-cm tendon defect was created. Sheep were randomly allocated to group 1, a defect; group 2, where an unseeded collagen scaffold was implanted; or group 3, which received the implantation of a collagen scaffold seeded with autologous tenocytes. Twelve weeks postoperatively, tendon regeneration was examined histologically and biomechanically. RESULTS: The histology of the neotendons of group 3 showed better fiber patterns, a higher production of proteoglycans, and an increased genesis of collagen III in contrast to groups 1 and 2. Immunostaining revealed less tissue dedifferentiation, a more structured cartilage layer, and homogeneous cartilage-bone transition in group 3 in comparison with groups 1 and 2. Biomechanically, the tensile strength of the reconstructed tendons in group 3 (mean load to failure, 2516 N; SD, 407.5 N) was approximately 84% that of the native tendons (mean load to failure, 2995 N; SD, 223.1 N) without statistical significance. A significant difference (P = .0095) was registered between group 1 (66.9% with a mean load to failure of 2004 N; SD, 273.8 N) and the native tendons, as well as between group 2 (69.7% with a mean load to failure of 2088 N; SD, 675.4 N) and the native tendons for mean ultimate tensile strength. In breaking stress, a significant difference (P = .0095) was seen between group 1 (mean breaking stress, 1335 N/mm2; SD, 182.7 N/mm2) and the native tendons, as well as between group 2 (breaking stress, 1392 N/mm2; SD, 450.2 N/mm2) and the native tendons (mean breaking stress, 1996 N/mm2; SD, 148.7 N/mm2). Again, there was no significant difference between group 3 (mean breaking stress, 1677 N/mm2; SD, 271.7 N/mm2) and the native tendons. CONCLUSION: Autologous tenocytes seeded on collagen scaffolds yield enhanced biomechanical results after tendon-bone reconstruction as compared with unseeded scaffolds in an acute setting. Biomechanical results and histological outcomes were promising, showing that the use of autologous tenocytes with specific carrier matrices could be a novel approach for repairing rotator cuff tears. CLINICAL RELEVANCE: This study supports the use of tenocytes and scaffolds for improving the quality of tendon-bone regeneration.

Graft Hypertrophy After Third-Generation Autologous Chondrocyte Implantation Has No Correlation With Reduced Cartilage Quality: Matched-Pair Analysis Using T2-Weighted Mapping.

BACKGROUND: Graft hypertrophy is common after matrix-based autologous chondrocyte implantation (ACI) in the knee joint. However, it is not clear whether graft hypertrophy is a complication or an adjustment reaction in the cartilage regeneration after ACI. PURPOSE: To analyze the cartilage quality of the ACI regeneration with graft hypertrophy using T2-weighted mapping. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: A total of 91 patients with isolated cartilage defects (International Cartilage Repair Society [ICRS] grade III-IV) of the knee were treated with Novocart 3D, a third-generation, matrix-based, ACI procedure in the knee joint. All patients were evaluated with a standardized magnetic resonance imaging protocol after 3, 6, 12, 24, 36, and 48 months postoperatively. For morphological and biochemical assessment, the T2-weighted relaxation times of the ACI grafts as well as the healthy surrounding cartilage were determined. The results of the 20 patients with graft hypertrophy (hypertrophic group) were compared with the results of 21 matched patients without graft hypertrophy (nonhypertrophic group) after ACI. Match-paired analysis was performed by comparison of age, defect size, and body mass index. RESULTS: The T2-weighted relaxation times of the ACI graft showed significant improvement, with values decreasing from 52.1 milliseconds to 33.3 milliseconds after 48 months. After 12 months, the T2-weighted relaxation times were constant and comparable with the healthy surrounding cartilage. Graft hypertrophy was seen in 22% (n = 20) of the patients who underwent ACI. A significant difference in T2-weighted relaxation times between the hypertrophic and nonhypertrophic ACI grafts could not be found except after 36 months (hypertrophic T2-weighted relaxation time/nonhypertrophic T2-weighted relaxation time: 3 months, 48.0/56.4 ms, P = .666; 6 months, 45.6/42.5 ms, P = .280; 12 months, 39.3/34.7 ms, P = .850; 24 months, 34.8/32.2 ms, P = .742; 36 months, 34.6/38.2 ms, P = .030; 48 months, 34.2/32.3 ms, P = .693). CONCLUSION: The T2-weighted relaxation time of the ACI graft cartilage showed significant improvements over the observation period of 4 years postoperatively. After 2 years, graft maturation was completed. Graft hypertrophy after ACI was seen in 22% of the patients. Reduced cartilage quality could not be found in patients with graft hypertrophy after ACI.

Allogenic Myocytes and Mesenchymal Stem Cells Partially Improve Fatty Rotator Cuff Degeneration in a Rat Model.

PURPOSE: Rotator cuff (RC) tears result not only in functional impairment but also in RC muscle atrophy, muscle fattening and eventually to muscle fibrosis. We hypothesized that allogenic bone marrow derived mesenchymal stem cells (MSC) and myocytes can be utilized to improve the rotator cuff muscle fattening and increase the atrophied muscle mass in a rat model. METHODS: The right supraspinatus (SSP) tendons of 105 inbred rats were detached and muscle fattening was provoked over 4 weeks; the left side remained untouched (control group). The animals (n = 25) of the output group were euthanized after 4 weeks for reference purposes. The SSP-tendon of one group (n = 16) was left unoperated to heal spontaneously. The SSP-tendons of the remaining 64 rats (4 groups with n = 16) were repaired with transosseous sutures. One group received a saline solution injection in the SSP muscle belly, two other groups received 5 × 106 allogenic myocytes and 5 × 106 allogenic MSC injections from donor rats, respectively, and one group received no additional treatment. After 4 weeks of healing, the supraspinatus muscle mass was compared quantitatively and histologically to all the treated groups and to the untreated contralateral side. RESULTS: In the end of the experiments at week 8, the myocyte and MCS treated groups showed a significantly higher muscle mass with 0.2322 g and 0.2257 g, respectively, in comparison to the output group (0.1911 g) at week 4 with p < 0.05. There was no statistical difference between the repaired, treated, or spontaneous healing groups at week 8. Supraspinatus muscle mass of all experimental groups of the right side was significantly lower compared to the untreated contralateral muscle mass. CONCLUSION: This defect model shows that the injection of allogenic mycocytes and MSC in fatty infiltrated SSP muscles is better than no treatment and can partially improve the SSP muscle belly fattening. Nevertheless, a full restoration of the degenerated and fattened rotator cuff muscle to its original condition is not possible using myocytes and MSC in this model.

The Primary Stability of a Bioabsorbable Poly-L-Lactic Acid Suture Anchor for Rotator Cuff Repair Is Not Improved with Polymethylmethacrylate or Bioabsorbable Bone Cement Augmentation.

BACKGROUND: The incidence of osteoporosis and rotator cuff tears increases with age. Cement augmentation of bones is an established method in orthopedic and trauma surgery. QUESTIONS/PURPOSES: This study analyses if polymethylmethacrylate or bioabsorbable cement can improve the primary stability of a bioabsorbable suture anchor in vitro in comparison to a non-augmented suture anchor in osteoporotic human humeri. METHODS: The trabecular bone mineral density was measured to ensure osteopenic human specimens. Then the poly-l-lactic acid Bio-Corkscrew® FT was implanted in the greater tuberosity footprint with polymethylmethacrylate Refobacin® cement augmentation (n = 8), with Cerament™ Bone Void Filler augmentation (n = 8) and without augmentation (n = 8). Using a cyclic testing protocol, the failure loads, system displacement, and failure modes were recorded. RESULTS: The Cerament™ augmented Bio-Corkscrew® FT yielded the highest failure loads (206.7 N), followed by polymethylmethacrylate Refobacin® augmentation (206.1 N) and without augmentation (160.0 N). The system displacement was lowest for Cerament™ augmentation (0.72 mm), followed by polymethylmethacrylate (0.82 mm) and without augmentation (1.50 mm). Statistical analysis showed no significant differences regarding the maximum failure loads (p = 0.1644) or system displacement (p = 0.4199). The main mode of failure for all three groups was suture slippage. CONCLUSION: The primary stability of the Bio-Corkscrew® FT is not influenced by bone cement augmentation with polymethylmethacrylate Refobacin® or with bioabsorbable Cerament™ in comparison to the non-cemented anchors. The cement augmentation of rotator cuff suture anchors in osteoporotic bones remains questionable since biomechanical tests show no significant advantage.

Reference Values of Flexion and Supination in the Elbow Joint of a Cohort without Shoulder Pathologies.

BACKGROUND: After surgery of the long head of the biceps tendon, the examination of the biceps brachii muscle function and strength is common clinical practice. The muscle strength is usually compared with the uninjured contralateral side or with a matched pair group assuming that the uninjured side can be used as an appropriate reference. HYPOTHESIS/PURPOSE: The purpose of this study was to define reference values of the supination and flexion strength in the elbow joint and to investigate the influence of the arm positions and various anthropometric factors. METHODS: 105 participants without any shoulder pathologies were enrolled. A full medical history was obtained and a physical examination was performed. The bilateral isometric testing included the supination torque in various forearm positions and elbow flexion strength with a custom engineered dynamometer. Multiple linear regression analysis was used to investigate the correlation of the strength and anthropometric factors. RESULTS: Only age and gender were significant supination and flexion strength predictors of the elbow. Hence, it was possible to calculate a gender-specific regression line for each forearm position to predict the age-dependent supination torque. The supination strength was greatest with the arm in 90° elbow flexion and the upper arm in full pronation.

Cell Toxicity in Fibroblasts, Tenocytes, and Human Mesenchymal Stem Cells-A Comparison of Necrosis and Apoptosis-Inducing Ability in Ropivacaine, Bupivacaine, and Triamcinolone.

PURPOSE: To analyze the ability of ropivacaine, bupivacaine, and triamcinolone to induce apoptosis and necrosis in fibroblasts, tenocytes, and human mesenchymal stem cells. METHODS: Human dermal fibroblasts, adipose-derived human mesenchymal stem cells (hMSCs), and tenocytes gained from the rotator cuff tendon were seeded with a cell density of 0.5 × 104/cm2. One specimen of ropivacaine, bupivacaine, and triamcinolone was tested separately on the cells with separate concentrations of 0.5%, 0.25%, and 0.125% for each specimen. The negative control received no agent, only a change of medium. The incubation period for each agent was 30 minutes. After a change of medium and 1 hour, 24 hours, and 7 days of incubation, 104 cells were harvested and analyzed via fluorescence-activated cell sorting with double-staining with annexin V and propidium iodide. Statistical analysis to determine significant difference (P < .05) between the groups with SPSS statistics 23 through one-way analysis of variance with a univariate general linear model was performed. RESULTS: Bupivacaine showed necrosis-inducing effects on fibroblasts and tenocytes, with the necrotic effect peaking at 0.5% and 0.25%. Ropivacaine and triamcinolone caused no significant necrosis. Compared with fibroblasts and tenocytes, hMSCs did not show significant necrotic or apoptotic effects after exposure to bupivacaine. Overall, no significant differences in apoptosis were detected between different cell lines, varying concentrations, or time measurements. CONCLUSIONS: Bupivacaine 0.5% and 0.25% have the most necrosis-inducing effects on fibroblasts and tenocytes. Ropivacaine caused less necrosis than bupivaine. Compared with fibroblasts and tenocytes, hMSCs were not affected by necrosis using any of the tested agents. A significant apoptosis-inducing effect could not be detected for the different cell lines. CLINICAL RELEVANCE: Possible cell toxicity raises questions of concern for intra-articular injections using local anesthetics and corticosteroids. The present study demonstrates the necrotic and apoptotic effects of ropivacaine, bupivacaine, and triamcinolone and may give recommendations for intra-articular use of local anesthetics and corticosteroids.

Analysis of the autologous chondrocyte quality of matrix-based autologous chondrocyte implantation in the knee joint.

PURPOSE: Matrix based autologous chondrocyte implantation is an established method for treatment of full cartilage defects in the knee joint, but little is known about the influence of the implanted autologous chondrocyte quality and its clinical value. The aim of this study is to evaluate the influence of the gene expression of the implanted autologous chondrocytes on the clinical outcomes in the follow-up period of three years. METHODS: Biological parameters of the implanted chondrocytes were analysed histologically and immunohistologically. An analysis of the gene expression of the relevant chondrogenic dedifferentiation markers was performed as well. In order to detect the rate of apoptosis, we analysed specific apoptosis markers. To evaluate the clinical outcome, the International Knee Documentation Committee (IKDC) subjective score and the visual analogue scale (VAS) were used pre-operatively and after 0.5, one, two and three years. RESULTS: Significantly improved clinical scores were observed. The subjective IKDC score increased from 50.6 ± 20.7 points to 69.3 ± 26.1 points at three years (p = 0.001). The implanted chondrocytes showed a typical expression of the chondrogenic markers with a high rate of collagen type II expression without dedifferentiation. The analysed differentiation, dedifferentiation and apoptosis markers showed no influence on the clinical outcome. CONCLUSIONS: The implanted autologous chondrocytes have a high chondrogenic quality with a high rate of collagen type II expression without dedifferentiation. An influence of differentiation, de-differentiation and apoptosis marker gene expression on the clinical outcomes could not be found in a follow-up period of three years. LEVEL OF EVIDENCE: Case series; Level of evidence, 3.

Revision surgery after third generation autologous chondrocyte implantation in the knee.

PURPOSE: Third generation autologous chondrocyte implantation (ACI) is an established treatment for full thickness cartilage defects in the knee joint. However, little is known about cases when revision surgery is needed. The aim of the present study is to investigate the complication rates and the main reasons for revision surgery after third generation autologous chondrocyte implantation in the knee joint. It is of particular interest to examine in which cases revision surgery is needed and in which cases a "wait and see" strategy should be used. METHODS: A total of 143 consecutive patients with 171 cartilage defects were included in this study with a minimum follow-up of two years. All defects were treated with third generation ACI (NOVACART®3D). Clinical evaluation was carried out after six months, followed by an annual evaluation using the International Knee Documentation Committee (IKDC) subjective score and the visual analogue scale (VAS) for rest and during activity. Revision surgery was documented. RESULTS: The revision rate was 23.4 % (n = 36). The following major reasons for revision surgery were found in our study: symptomatic bone marrow edema (8.3 %, n = 3), arthrofibrosis (22.2 %, n = 8) and partial graft cartilage deficiency (47.2 %, n = 17). The following revision surgery was performed: retrograde drilling combined with Iloprost infusion therapy for bone marrow oedema (8.4 %, n = 3), arthroscopic arthrolysis of the suprapatellar recess (22.2 %, n = 8) and microfracturing/antegrade drilling (47.3 %, n = 17). Significant improvements of clinical scores after revision surgery were observed. CONCLUSION: Revision surgery after third generation autologous chondrocyte implantation is common and is needed primarily in cases with arthrofibrosis, partial graft cartilage deficiency and symptomatic bone marrow oedema resulting in a significantly better clinical outcome.

Bone Marrow Edema in the Knee and Its Influence on Clinical Outcome After Matrix-Based Autologous Chondrocyte Implantation: Results After 3-Year Follow-up.

BACKGROUND: Third-generation autologous chondrocyte implantation (ACI) is an established method for treatment of full-thickness cartilage defects in the knee joint. Subchondral bone marrow edema (BME) is frequently observed after ACI, with unknown pathogenesis and clinical relevance. PURPOSE: To investigate the occurrence and clinical relevance of BME after third-generation ACI in the knee joint during the postoperative course of 36 months. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 38 circumscribed full-thickness cartilage defects in 30 patients were included in this study. All defects were treated with third-generation ACI (Novocart 3D). A standardized MRI examination was carried out after 1.5, 3, 6, 12, 24, and 36 months. Bone marrow edema was observed in 78.9% of defects over the postoperative course, with initial occurrence in the first 12 months. The size of the BMEs were determined according to their maximum diameter and were classified as small (<1 cm), medium (<2 cm), large (<4 cm), and very large (diffuse; >4 cm). Clinical outcomes in patients were analyzed by use of the International Knee Documentation Committee (IKDC) scoring system and a visual analog scale for pain. RESULTS: There were 5.3% (n=2) small, 28.9% (n=11) medium, 34.2% (n=13) large, and 10.5% (n=4) very large BMEs. In a subgroup analysis, cartilage defects of the medial femoral condyle showed significantly higher frequency of BME than did patellar defects. Clinical scores showed significant improvements throughout the entire study course (P<.05). Clinical patient outcome did not correlate with presence of BME at any time period (P>.05). CONCLUSION: Midterm clinical results of the matrix-based third-generation ACI showed a substantial amount of BME over a 36-month follow-up, but this did not correlate with worse clinical outcome. Patients with femoral cartilage defects were more often affected than were those with patellar cartilage defects.

Influence of Temperature on the Biomechanical Stability of Titanium, PEEK, Poly-L-Lactic Acid, and ß-Tricalcium Phosphate Poly-L-Lactic Acid Suture Anchors Tested on Human Humeri In Vitro in a Wet Environment.

PURPOSE: The purpose of this study was to analyze the biomechanical integrity of suture anchors of different materials (titanium, PEEK [polyether ether ketone], poly-L-lactic acid [PLLA], and ß-tricalcium phosphate PLLA) and almost identical design for rotator cuff repair in human humeri positioned in a water bath at room and body temperature undergoing cyclic loading rather than single-pull or static tests. METHODS: Four different anchor models (n = 6) were tested using healthy human cadaveric humeri in a water bath thermostatically regulated at 20°C and 37°C. A cyclic testing protocol was used. The maximum failure load, the system displacement, and the respective mode of failure were recorded. RESULTS: There were no significant differences regarding the maximum failure load values between the 20°C groups and 37°C groups for the 4 different anchor materials. The displacement values for the 20°C groups and 37°C groups also were not statistically significant. Anchor and suture dislocations were the predominant modes of failure; suture ruptures were observed in few cases. CONCLUSIONS: This study shows that there are no significantly relevant differences regarding the maximum failure loads and the displacement values of the tested suture anchor systems in a wet environment at 20°C or 37°C. The temperature differences do not seem to affect the modes of failure either. CLINICAL RELEVANCE: Titanium, PEEK, PLLA, and ß-tricalcium phosphate PLLA suture anchors for rotator cuff repair can be expected-on the basis of this investigation comparing laboratory temperature with body temperature and a wet environment-to perform in vivo similar to in vitro testing.

Assessment of essential characteristics of two different scaffolds for tendon in situ regeneration.

PURPOSE: Rotator cuff tears are challenging as the rate of re-ruptures remains high. Thus, new therapeutic strategies need to be developed. Tendon in situ regeneration (TSR) attempts to produce cell-scaffold constructs in vitro, which can produce tendinous tissue of high quality after replantation. Therefore, it is essential to find suitable scaffolds that can provide acceptable biofunctionality and biocompatibility. This study compares characteristics of scaffolds for in situ regeneration: a polyglycolic acid/PDS scaffold (PP-sca) (Ethisorb, Ethicon, Germany) and a collagen sponge (col-spo) (TissueTek, Germany) with a basal strengthening membrane. METHODS: Tendon-derived cells (TDCs) were isolated from the long head of the biceps tendon. Gene expression for collagen type I, collagen type III, decorin, scleraxis and tenomodulin was analysed in the third cell passage. Cell proliferation in cell seeded scaffolds was tested using a WST-1 assay. In addition, the tensile strength of both scaffolds was measured using a universal-testing machine (Zwick/Roell, Ulm, Germany). RESULTS: The results from this study indicate a genotypic drift during the in vitro cultivation of the TDCs. The PP-sca showed good biofunctional results, including low initial loss of cells after cell seeding. The proliferation rates were approximately equal in each type of scaffold. The col-spo provided superior tensile strength compared with the PP-sca (p < 0.01). CONCLUSION: Overall, the col-spo seems to be more suitable for TSR. It may become a clinical alternative in the future to achieve more satisfying results, concerning function and pain. LEVEL OF EVIDENCE: Experimental study/case series, Level IV.

Does footprint preparation influence tendon-to-bone healing after rotator cuff repair in an animal model?

PURPOSE: The aim of this study was to investigate the influence of footprint spongialization and radiofrequency ablation on rotator cuff repair outcomes compared with an untreated group in a rat model. METHODS: We randomly assigned 189 Sprague-Dawley rats to either a spongialization, radiofrequency ablation, or untreated group. After separation of the supraspinatus tendon from the greater tubercle, the footprint was prepared by removing the cortical bone with a burr (spongialization), was prepared by ablating soft tissue with a radiofrequency ablation device, or was left unaltered (untreated). Biomechanical testing (after 7 weeks, n = 165) and histologic analysis after 1 and 7 weeks (n = 24) followed reinsertion. RESULTS: The mean load to failure was 17.51 ± 4.46 N/mm(2) in the spongialization group, 15.56 ± 4.85 N/mm(2) in the radiofrequency ablation group, and 19.21 ± 5.19 N/mm(2) in the untreated group. A significant difference was found between the spongialization and radiofrequency ablation groups (P = .0409), as well as between the untreated and radiofrequency ablation groups (P = .0014). There was no significant difference between the spongialization and untreated groups (P = .2456). The mean area of fibrocartilage transition, characterized by the presence of type II collagen, was larger after 1 and 7 weeks in the spongialization group (0.57 ± 0.1 mm(2) and 0.58 ± 0.1 mm(2), respectively) and untreated group (0.51 ± 0.1 mm(2) and 0.51 ± 0.2 mm(2), respectively) than in the radiofrequency ablation group (0.11 ± 0.1 mm(2) and 0.4 ± 0.1 mm(2), respectively) with P < .05 and P < .01. CONCLUSIONS: The results of this study show that radiofrequency ablation of the footprint results in a poor biomechanical and histologic outcome in an animal model. No preparation of the footprint has the same effect as spongialization. CLINICAL RELEVANCE: Different techniques of footprint preparation in rotator cuff repair may influence tendon-to-bone healing.

Fentanyl is less toxic on adult human mesenchymal stem cells compared to ropivacaine when used intraarticularly. A controlled in vitro study.

The purpose of this study was to evaluate the toxicity of ropivacaine and fentanyl on adult human mesenchymal stem cells (hMSC). hMSC's were seeded in monolayer triple-flasks and then plated into 96-well plates at a density of 5000 cells per well. After fully aspirating the culture medium, ropivacaine or fentanyl in its corresponding concentration (0.5%, 0.25%, 0.125% for ropivacaine and 0.05%, 0.025%, 0.0125% for fentanyl) or culture medium only was added to each well. After 30 min, the anaesthetic was removed and fresh culture medium was added. hMSCs mitochondrial activity as a marker of cell proliferation and apoptosis marker was evaluated after 1, 24 h and 7 days. Proliferation was significantly decreased after a 30 min exposure to 0.5% and 0.125% ropivacaine, respectively compared to the control group after 24 h (p < 0.001). Simultaneously, apoptosis was significantly induced. Proliferation of hMSC's was decreased after 24 h when exposed to 0.05%, 0.025% and 0.0125% fentanyl (p < 0.001). Apoptosis was only induced 24 h after an exposure to 0.05% fentanyl. Our data suggest that both drugs have a concentration-dependent effect on proliferation in adult hMSC's in vitro. This effect was more distinct with ropivacaine compared to fentanyl. Translating these results into clinical practice, this in vitro study suggests fentanyl as a potentially less toxic analgetic drug for intraarticular application after arthroscopic bone marrow stimulation or rotator cuff repair with comparable to prolonged pain reduction.

Sports activities after medial unicompartmental knee arthroplasty Oxford III-what can we expect?

PURPOSE: Excellent long-term results have been reported for implantation of unicompartmental knee arthroplasty (UKA). In many patients the desire for improvement in function often includes an aspiration to return to sports. The purpose of our study was to evaluate physical activities after medial Oxford-III (Biomet) UKA surgery. METHODS: Patients' physical activity before and after the surgery was assessed using a self reporting questionnaire. We used the Oxford knee scoring system (OKS), the WOMAC-, the Knee society- (KSS) and the UCLA-score to assess postoperative knee function. The mean follow-up was 4.2 years. The female-to-male ratio was 1.3:1. The mean age at surgery was 65.3 years. RESULTS: Of the 131 patients studied 78 participated in some kind of sports before surgery (mean age 64.4 years), while 53 patients did not perform any sports (mean age 66.5 years) (p > 0.05). At follow-up the patients in the active group were significantly younger than the patients in the inactive group (p < 0.05). The majority of patients (80.1 %) returned to their level of sports activity after UKA surgery. Six patients took up sports after surgery while 15 patients stopped their sports. Among the active patients we found a shift from high- towards low-impact sports. The active patients had significantly higher scores for the OKS, KSS, WOMAC and UCLA score. The complication rate was comparable in both groups. CONCLUSION: Our study demonstrates that a high degree of patient satisfaction in terms of sports activity can be achieved using the Oxford-III UKA for medial osteoarthritis.

The incidence and clinical relevance of graft hypertrophy after matrix-based autologous chondrocyte implantation.

BACKGROUND: Graft hypertrophy is the most common complication of periosteal autologous chondrocyte implantation (p-ACI). PURPOSE: The aim of this prospective study was to analyze the development, the incidence rate, and the persistence of graft hypertrophy after matrix-based autologous chondrocyte implantation (mb-ACI) in the knee joint within a 2-year postoperative course. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Between 2004 and 2007, a total of 41 patients with 44 isolated cartilage defects of the knee were treated with the mb-ACI technique. The mean age of the patients was 35.8 years (standard deviation [SD], 11.3 years), and the mean body mass index was 25.9 (SD, 4.2; range, 19-35.3). The cartilage defects were arthroscopically classified as Outerbridge grades III and IV. The mean area of the cartilage defect measured 6.14 cm(2) (SD, 2.3 cm(2)). Postoperative clinical and magnetic resonance imaging (MRI) examinations were conducted at 3, 6, 12, and 24 months to analyze the incidence and course of the graft. RESULTS: Graft hypertrophy developed in 25% of the patients treated with mb-ACI within a postoperative course of 1 year; 16% of the patients developed hypertrophy grade 2, and 9% developed hypertrophy grade 1. Graft hypertrophy occurred primarily in the first 12 months and regressed in most cases within 2 years. The International Knee Documentation Committee (IKDC) and visual analog scale (VAS) scores improved during the postoperative follow-up time of 2 years. There was no difference between the clinical results regarding the IKDC and VAS pain scores and the presence of graft hypertrophy. CONCLUSION: The mb-ACI technique does not lead to graft hypertrophy requiring treatment as opposed to classic p-ACI. The frequency of occurrence of graft hypertrophy after p-ACI and mb-ACI is comparable. Graft hypertrophy can be considered as a temporary excessive growth of regenerative cartilage tissue rather than a true graft hypertrophy. It is therefore usually not a persistent or systematic complication in the treatment of circumscribed cartilage defects with mb-ACI.

Heat distribution of polymerisation temperature of bone cement on the spinal canal during vertebroplasty.

PURPOSE: In the last 15 years, vertebroplasty and kyphoplasty have become established operative procedures for treating osteoporotic vertebral-body fractures and vertebral bodies afflicted with metastases. These procedures are quickly performed with few personnel and material resources and have a low rate of complications. However, cases of neurological impairment are reported in the scientific literature. We analysed whether potentially harmful heat is radiated/conducted by the polymerisation temperature of polymethylmethacrylate (PMMA) bone cement in the spinal canal. METHODS: We performed vertebroplasty on 25 vertebral bodies and measured the temperature distribution during polymerisation of bone cement within the spinal canal using heat probes placed in the respective areas. The vertebral bodies were located in a circulating water bath at 37°C. RESULTS: During polymerisation of the bone cement, a temperature rise was measured. The peak temperature was reached after few minutes. Temperature curves differed; a maximum temperature of up to 43.16°C was detected for a few seconds only. CONCLUSION: When vertebroplasty is performed correctly, there is no temperature development that could eventually damage the spinal cord or spinal nerves.