Effect of shape and size of supraspinatus tears on rotator cuff strain distribution: an in vitro study.

BACKGROUND: The impact of the size and shape of a supraspinatus tear on the strain of the intact rotator cuff and the kinematics of the shoulder is still unknown. This, however, can be relevant when deciding whether surgical reconstruction is required to prevent an increase in a tendon defect. In this study, the effect of tear width and shape on rotator cuff strain and glenohumeral kinematics was evaluated during active abduction. METHODS: Twelve fresh-frozen cadaveric shoulders with intact rotator cuffs were used in this study. We created 50% and 100% wide (full-thickness) crescent-shaped (CS) tears (n = 6) and reverse L-shaped (rLS) tears (n = 6) in the supraspinatus tendon and measured strain and kinematics during active humeral elevation until 30°. RESULTS: Both tear shapes and sizes led to an increase in internal rotation, supraspinatus loading force, and superior translation of the humerus. For the 100% wide tear size, anterior translation was observed in the CS tear group, whereas in the rLS tear group, this translation occurred mainly in the posterior direction. Strain was higher in the infraspinatus during the first 25° of abduction in comparison with the supraspinatus tendon in both tear shape groups. An analysis of the anterior and posterior tear borders showed a higher strain concentration on the same side of the tear in the CS tear group with 50% and 100% wide tears. CONCLUSIONS: The influence of different tear shapes on translation in the anterior-posterior direction was evident as both CS and rLS tears led to an oppositely directed translation of the humeral head. The strain analysis showed a stress-shielding effect of the infraspinatus at the beginning of abduction. Therefore, special attention must be paid to correctly identify the tear extension and adequately reconstruct the rotator cuff footprint. Moreover, the constant location of maximum strain in the CS tear group may lead to an earlier progression than in the rLS tear group.

Effect of the defect localization and size on the success of third-generation autologous chondrocyte implantation in the knee joint.

INTRODUCTION: Femoral and patellar cartilage defects with a defect size > 2.5 cm2 are a potential indication for an autologous chondrocyte implantation (ACI). However, the influence of the localization and the absolute and relative defect size on the clinical outcome has not yet been determined. The purpose of this study is to analyze the influence of the localization and the absolute and relative defect size on the clinical outcome after third-generation autologous chondrocyte implantation. METHODS: A total of 50 patients with cartilage defects of the knee were treated with third-generation autologous chondrocyte implantation (Novocart® 3D). A match paired analysis was performed of 25 treated femoral and 25 treated patella defects with a follow-up of three years. MRI data was used to do the manual segmentation of the cartilage layer throughout the knee joint. The defect size was determined by taking the defect size measured in the MRI in relation to the whole cartilage area. The clinical outcome was measured by the IKDC score and VAS pre-operatively and after six, 12, 24, and 36 months post-operatively. RESULTS: IKDC and VAS scores showed a significant improvement from the baseline in both groups. Femoral cartilage defects showed significantly superior clinical results in the analyzed scores compared to patellar defects. The femoral group improved IKDC from 33.9 (SD 18.1) pre-operatively to 71.5 (SD 17.4) after three years and the VAS from 6.9 (SD 2.9) pre-operatively to 2.4 (SD 2.5) after three years. In the patellar group, IKDC improved from 36.1 (SD 12.6) pre-operatively to 54.7 (SD 20.3) after three years and the VAS improved from 6.7 (SD 2.8) pre-operatively to 3.4 (SD 2.) after three years. Regarding the defect size, results showed that the same absolute defect size at med FC (4.8, range 2-15) and patella (4.6, range 2-12) has a significantly different share of the total cartilaginous size of the joint compartment (med FC: 6.7, range 1.2-13.9; pat: 18.9, range 4.0-47.0). However, there was no significant influence of the relative defect size on the clinical outcome in either patellar or femoral localization. CONCLUSION: Third-generation autologous chondrocyte implantation in ACI-treated femoral cartilage defects leads to a superior clinical outcome in a follow-up of three years compared with patellar defects. No significant influence of the defect size was found in either femoral or patellar cartilage defects.

Accuracy of a non-invasive CT-based measuring technique for cement penetration depth in human tibial UKA.

BACKGROUND: Aseptic loosening of the tibial component remains a major cause of failure in unicompartmental knee arthroplasty (UKA) and may be related to micro-motion at the cement-bone interface due to insufficient cement penetration depth. Cement penetration is therefore taken as an indicator of solid fixation strength and primary stability. However, its non-invasive clinical assessment remains difficult in vivo as conventional x-ray is prone to distortion and CT-scans (computed tomography) are difficult to assess due to metal artifacts. The purpose of this study was to develop and validate a reliable in vivo measuring technique of cement penetration depth in human tibial UKA. METHODS: In an experimental setting, twelve UKA were implanted in fresh-frozen human cadaver knees using a minimal-invasive medial approach. Cement penetration depth was then measured via 1) virtual 3D-models based on metal artifact reduced CT-scans and 2) histological evaluation of nine serial cross-section cuts through the implant-cement-bone-interface. Subsequently, a concordance analysis between the two measuring techniques was conducted. RESULTS: The average cement penetration depth was 1) 2.20 mm (SD 0.30 mm) measured on metal artifact reduced CT-scans and 2) 2.21 mm (SD = 0.42) measured on serial cuts (p = 0.956). The mean difference between both techniques was 0.01 mm (SD 0.31 mm) and the Person correlation coefficient was r = 0.686 (p = 0.014). All differences were within the upper and lower limit of agreement. There was no evidence of any significant proportional bias between both techniques (p = 0.182). CONCLUSIONS: CT-based non-invasive measurement of cement penetration depth delivers reliable results in measuring the penetration depth in tibial UKA. Thereby, it enables clinicians and researchers to assess the cement penetration for in vivo diagnostics in the clinical setting as well as in vitro biomechanical research with subsequent application of load to failure on the implant-cement-bone-interface.

Impact of a double-layer cementing technique on the homogeneity of cementation and the generation of loose bone cement fragments in tibial unicompartmental knee arthroplasty.

BACKGROUND: The objective of this study was to evaluate the impact of a single- vs. double-layer cementing technique on morphological cementation and the generation of microscopic cement layers or loose cement fragments in unicompartmental knee arthroplasty (UKA). METHODS: UKAs were implanted in 12 cadaver knees. The specimens were divided into two groups of comparable bone mineral density. Six UKAs were implanted using a single-layer cementing technique (group A) and six UKAs were implanted using a double-layer cementing technique (group B). Morphological cementation was assessed on nine cuts through the implant-cement-bone interface in the frontal plane. Loose bone cement fragments and the microscopically quality of layer formation were evaluated. RESULTS: Contact between bone and prosthesis was observed in 45.4% of interfaces in group A and 27.8% in group B (p = 0.126). The significant increase of areas without visible cement interlocking in the anteroposterior direction in group A (p = 0.005) was not evident in group B (p = 0.262). Penetration around the peg tended to occur more frequently in group B (67.5% vs. 90.6% p = 0.091). Scanning electron microscopy identified no evidence of fissure formations within the bilaminar cement mantle. Free bone cement fragments were documented in 66.7% in both groups with no difference concerning mass (p = 1.0). CONCLUSIONS: This in-vitro study showed a tendency towards a more homogenous cementation of tibial UKAs using a double-layer cementing technique, although most of the differences did not reach the level of significance. However, theoretical downsides of the double-layer cementing technique such as an increased formation of free bone fragments or a microscopically fissure formation within the cement layer could not be detected either.

Periprosthetic bone quality affects the fixation of anatomic glenoids in total shoulder arthroplasty: in vitro study.

BACKGROUND: Glenoid loosening, a common complication of shoulder arthroplasty, could relate to implant design and bone quality. However, the role of bone density has not been tested experimentally yet. In this study, tests on cadaveric specimens of varying bone density were performed to evaluate the effects of bone quality on loosening of typical anatomic glenoid implants. METHODS: Cadaveric scapulae scanned with a quantitative computed tomography scanner to determine bone mineral density (BMD) were implanted with either pegged or keeled cemented glenoid components and tested under constant glenohumeral load while a humeral head component was moved cyclically in the inferior and superior directions. Implant superior and inferior edge lifting, defined as displacement from the underlying bone, was measured with linear variable differential transducers until we reached 23,000 test cycles, and statistical testing was performed for differences in edge lifting due to implant design and related to periprosthetic BMD. RESULTS: Edge lifting was statistically significant at all time points, but on average, implant design had no effect. Lifting was highest in specimens in which BMD below the lifting edge was lower, with trends of increased displacement with decreased BMD. CONCLUSIONS: Implant lifting was greater in glenoids of lower bone density for both implant designs. This finding suggests that fixation failure will most likely occur in bone of lower density and that the fixation design itself may play a secondary role.

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.

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.

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.

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.

Early resumption of physical activities leads to inferior clinical outcomes after matrix-based autologous chondrocyte implantation in the knee.

PURPOSE: Matrix-based autologous chondrocyte implantation is a well-established operation procedure for full cartilage defects. When to resume physical activity after matrix-based autologous chondrocyte implantation is controversial. Our hypothesis was that early resumption of physical activity leads to a worse clinical outcome after matrix-based autologous chondrocyte implantation in the knee two years post-operatively. Physical activity is defined as any kind of impact sport. METHODS: Forty-four patients with cartilage defects of the knee were treated with matrix-based autologous chondrocyte implantation (Novocart3D). All patients were assessed preoperatively and after a period of 24 months with the University of California Los Angeles (UCLA) Activity score. The return to physical activities or sports after matrix-based autologous chondrocyte implantation was documented. Patients were evaluated using the International Knee Documentation Committee Knee Examination Form and visual analogue scale for pain after 6, 12 and 24 months. RESULTS: Fifty-five percent showed an unchanged level of physical activity in the UCLA Activity score post-operatively. About 35% showed a lower level and 10% a higher level of physical activity. The average return to physical activities or sports after matrix-based autologous chondrocyte implantation procedure was 10.2 months. Patients with a later return of sports after 12 months showed significantly better clinical results after two years. In particular, patients who started practicing impact sport after 12 months post-operatively showed significantly better results. CONCLUSION: Resuming physical activity including impact sports without waiting at least 12 months after the operation leads to inferior outcomes up to 24 months after matrix-based autologous chondrocyte implantation. LEVEL OF EVIDENCE: Level IV.

Graft hypertrophy of matrix-based autologous chondrocyte implantation: a two-year follow-up study of NOVOCART 3D implantation in the knee.

PURPOSE: Graft hypertrophy is a major complication in the treatment for localized cartilage defects with autologous chondrocyte implantation (ACI) using periosteal flap and its further development, Novocart (a matrix-based ACI procedure). The aim of the present study is to investigate individual criteria for the development of graft hypertrophy by NOVOCART 3D implantation of the knee in the post-operative course of 2 years. METHODS: Forty-one consecutive patients with 44 isolated cartilage defects of the knee were treated with NOVOCART 3D implants. Individual criteria and defect-associated criteria were collected. Follow-up MRIs were performed at 3, 6, 12 and 24 months. The NOVOCART 3D implants were measured and classified. The modified MOCART Score was used to evaluate quality and integration of the NOVOCART 3D implants in MRI. RESULTS: Graft hypertrophy was observed in a total of 11 patients at all post-operative time points. We were able to show that NOVOCART 3D implantation of cartilage defects after acute trauma and osteochondritis dissecans (OCD) led to a significantly increased proportion of graft hypertrophy. No other individual criteria (age, gender, BMI) or defect-associated criteria (concomitant surgery, second-line treatment, defect size, fixation technique) showed any influence on the development of graft hypertrophy. The modified MOCART Score results revealed a significant post-operative improvement within 2 years. CONCLUSION: The aetiology of cartilage defects appears to have a relevant influence for the development of graft hypertrophy. Patients, who were treated with NOVOCART 3D implants after an acute event (acute trauma or OCD), are especially at risk for developing a graft hypertrophy in the post-operative course of two years. LEVEL OF EVIDENCE: Case series, Level IV.

UKA can be safely revised to primary knee arthroplasty by using an autologous bone plate from the proximal lateral tibia.

The bone-preservation by UKA in medial osteoarthritis constitutes only an advantage if in the case of revision an unconstrained TKA can be implanted. The aim of this study was to evaluate a revision technique using an autologous bone slice from the lateral to the medial proximal tibia. We report on 17 patients with a mean follow up of 3.1years. Patient's satisfaction and pain, WOMAC- and Oxford-Knee-Score, radiological and clinical knee symptoms/function were assessed. No loosening, wear or implant subsidence could be detected during the follow up. In comparison with results after primary TKA in the literature we found our clinical results to be within the range. The study demonstrates that thismethod is safe and produces good midterm results.

Conversion of UKA to TKA using identical standard implants-How does it compare to primary UKA, primary TKA and revision TKA?

BACKGROUND: UKA is a well-established treatment option for anteromedial osteoarthritis of the knee, resulting in superior functional outcomes but also higher revision rates than TKA. This study aimed to compare the outcomes of UKA, TKA, UKA converted to TKA using identical standard implants and revised TKA to support clinical decision-making. METHODS: In this study, we retrospectively examined 116 patients who underwent UKA, 77 patients who received TKA, 28 patients whose UKA was converted to TKA using identical standard implants, and 21 patients who had a one-stage revision of TKA. The mean age at operation was 66.5 years (39-90 years), with a mean BMI of 28.8 kg/m2 (17.4-58.8) and a mean follow-up period of four years (0.9-9.9 years). We assessed various PROMs, including Oxford Knee Score, UCLA score, KSS score, and a modified WOMAC-Score as well as patient satisfaction and ability to resume daily activities, work, and sports. RESULTS: The highest patient satisfaction was seen in the UKA. All scores were significantly higher for UKA than for TKA, converted UKA, and revised TKA. None of the scores showed a significant inferiority of converted UKA to TKA. In the case of revision, two scores showed significantly better results for converted UKA than for revised TKA. CONCLUSIONS: Our results indicated that patients initially treated with UKA did not have significantly worse functional outcomes after conversion to TKA, given the use of identical standard implants. This highlights the effectiveness of UKA as a therapeutic option with outcomes superior to those of primary TKA and the importance of a bone-sparing procedure. Conversely, revision TKA is linked to poorer functional outcomes compared to both primary arthroplasties.

[Functional outcomes and return to sports, work, and daily activities after revision UKA compared to primary UKA and TKA]. / Funktionelle Ergebnisse und Wiederaufnahme von Sport, Arbeit und Alltagsaktivitäten nach Revision eines Monoschlittens im Vergleich zur Primärimplantation eines Mono- und Doppelschlittens.

BACKGROUND: Unicompartmental knee arthroplasty (UKA), in addition to total knee arthroplasty (TKA), has been shown to be effective in the surgical treatment of knee osteoarthritis with appropriate patient selection. In clinical studies, it has demonstrated superior functional results with lower complication rates. In clinical practice, these advantages must be weighed against the disadvantage of an increased revision rate, especially in younger patients with sports and work activities. OBJECTIVES: The aim of this study was to compare the functional outcome as well as the time to return to daily activities, work, and sports after revision of UKA to TKA with those of primary UKA and primary TKA using a matched-pair analysis. MATERIALS AND METHODS: The study was based on a matched-pair analysis at two defined time points, always comparing 28 patients who underwent either revision of a UKA to a TKA, primary UKA, or primary TKA. Patients completed the Oxford Knee Score, UCLA score, Knee Society score, and WOMAC score during standardized follow-up. In addition, postoperative patient satisfaction and return to activities of daily living, work, and sports were recorded in a standardized manner, and a clinical examination was performed. RESULTS: The four functional scores studied showed a common trend in favor of UKA, followed by primary TKA and revision TKA. The differences between converted UKA and primary TKA were not significant. However, at 3.2 years after the last surgery, the results of the converted UKA were significantly lower than those of the primary UKA. Return to work and sports tended to occur the earliest after UKA, followed by TKA and the revision group. All groups showed a tendency to engage in low-impact sports. CONCLUSION: The functional results of revised UKA were significantly inferior to those of primary UKA based on a 3-year follow-up. Return to work, sports, and activities of daily living tended to take longer after revision than after primary implantation of either a UKA or a TKA.

Follow-up Treatment after Cartilage Therapy of the Knee Joint - a Recommendation of the DGOU Clinical Tissue Regeneration Working Group. / Nachbehandlung nach Knorpeltherapie am Kniegelenk ­ eine Empfehlung der AG Klinische Geweberegeneration der DGOU.

The first follow-up treatment recommendation from the DGOU's Clinical Tissue Regeneration working group dates back to 2012. New scientific evidence and changed framework conditions made it necessary to update the follow-up treatment recommendations after cartilage therapy.As part of a multi-stage member survey, a consensus was reached which, together with the scientific evidence, provides the basis for the present follow-up treatment recommendation.The decisive criterion for follow-up treatment is still the defect localisation. A distinction is made between femorotibial and patellofemoral defects. In addition, further criteria regarding cartilage defects are now also taken into account (stable cartilage edge, location outside the main stress zone) and the different methods of cartilage therapy (e. g. osteochondral transplantation, minced cartilage) are discussed.The present updated recommendation includes different aspects of follow-up treatment, starting with early perioperative management through to sports clearance and resumption of contact sports after cartilage therapy has taken place.

Improved accuracy in computer-assisted unicondylar knee arthroplasty: a meta-analysis.

PURPOSE: Inaccurate implantation rates of up to 30 % have been reported in cases using the conventional technique for implantation of a unicompartmental knee arthroplasty. Navigation should permit a more precise implantation, and several studies have investigated its role, albeit with a limited number of patients and inconsistent results. The aim of this meta-analysis was to compare risks of unsatisfactory outcomes in patients with navigated and conventional technique. METHODS: An electronic search was performed, and ten studies were eligible and included in the meta-analysis, with a total of 258 prostheses implanted with the navigated technique and 295 with the conventional one. The following items were analysed: radiological positioning of the femoral and the tibial component in the AP and lateral view, radiological analysis of the tibiofemoral mechanical axis and the difference in operating time between the two groups. Relative risks (RR) were calculated from the reported percentages of implants outside the optimal ranges defined by the manufacturers or the study groups. Natural logarithms of the relative risks were pooled by means of random effects models. RESULTS: For all the analysed radiological parameters, the RR of measurements outside the optimal ranges were less than 1 in the navigation group suggesting a reduction in the risk of outliers with navigation. The average operating time in the navigated group was 15.4 min (95 % CI: 10.2-20.6) longer than in the conventional group. CONCLUSION: The meta-analysis shows that the use of navigation systems in UKA leads to a more precise component position. Whether the more accurate position in UKA results in a better clinical outcome or long-term survival is yet unknown. Nevertheless, as a precise implant position appears to be beneficial, the use of navigation should be recommended for UKA. The limits defined by the manufacturers for an optimal positioning are not consistent.

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.

Analysis of orthopedic surgery of bone metastases in breast cancer patients.

BACKGROUND: Breast cancer is the most common malignancy and the second leading cause of death in women. Because bone metastases are a common finding in patients with breast cancer, they are of major clinical concern. METHODS: In 115 consecutive patients with bone metastases secondary to breast cancer, 132 surgical procedures were performed. Medical records and imaging procedures were reviewed for age, treatment of the primary tumor, clinical symptoms, surgical treatment, complications, and survival. RESULTS: The overall survival of patients with metastatic breast cancer was dependent on the site and the amount of the metastases. Age was not a prognostic factor for survival. If the result of the orthopaedic surgery was a wide resection (R0) survival was significantly better than in the R1 (marginal resection - tumor resection in sane tissue) or R2 (intralesional resection) situation. Concerning the orthopaedic procedures there was no survival difference. CONCLUSION: In conclusion a wide (R0) resection and the absence of pathological fracture and visceral metastases were predictive for longer survival in univariate analysis. Age and the type of orthopaedic surgery had no impact on survival in multivariate analysis. The resection margins lost significance. The standard of care for patients with metastatic breast cancer to the bone requires a multidisciplinary approach.

Collagen type I and decorin expression in tenocytes depend on the cell isolation method.

BACKGROUND: The treatment of rotator cuff tears is still challenging. Tendon tissue engineering (TTE) might be an alternative in future. Tenocytes seem to be the most suitable cell type as they are easy to obtain and no differentiation in vitro is necessary. The aim of this study was to examine, if the long head of the biceps tendon (LHB) can deliver viable tenocytes for TTE. In this context, different isolation methods, such as enzymatic digestion (ED) and cell migration (CM), are investigated on differences in gene expression and cell morphology. METHODS: Samples of the LHB were obtained from patients, who underwent surgery for primary shoulder arthroplasty. Using ED as isolation method, 0.2% collagenase I solution was used. Using CM as isolation method, small pieces of minced tendon were put into petri-dishes. After cell cultivation, RT-PCR was performed for collagen type I, collagen type III, decorin, tenascin-C, fibronectin, Scleraxis, tenomodulin, osteopontin and agreccan. RESULTS: The total number of isolated cells, in relation to 1 g of native tissue, was 14 times higher using ED. The time interval for cell isolation was about 17 hours using ED and approximately 50 days using CM. Cell morphology in vitro was similar for both isolation techniques. Higher expression of collagen type I could be observed in tenocyte-like cell cultures (TLCC) using ED as isolation method (p < 0.05), however decorin expression was higher in TLCC using CM as isolation method (p < 0.05). Dedifferentiation potential seemed to be similar for both isolation techniques. CONCLUSION: In summary tenocyte-like cells can be obtained with both isolation methods (ED and CM) from the LHB. As no obvious disadvantage could be seen using ED, this method is more suitable for clinical use, as time for cell isolation is shorter and a remarkably higher number of cells can be obtained. However, both isolation methods can further be improved.