Distalization and Medialization of Tibial Tuberosity for the Treatment of Potential Patellar Instability with Patella Alta.

Purpose The aim of the study was to test the distalization and medialization of the tibial tuberosity (DMTT) for the treatment of patellar instability associated with patella alta, focusing on residual instability and pain. Methods Twenty-four consecutive patients (26 knees) suffering from patellofemoral instability and patella alta were treated by DMTT. Two groups were identified, which differed for documented history of frank patella dislocation. The groups were named objective patellar instability (OPI) (history of dislocation) and potential patella instability (PPI) (no dislocation). Outcome was measured with visual analogue scale (VAS), Kujala score, and Tegner score. Comparison between groups was performed using Student's t -test, Wilcoxon rank score, and Fisher's exact test (significance at p < 0.05). Results At 50 ± 18 and 41 ± 18 months of follow-up, respectively, both PPI and OPI groups obtained a significant pain reduction and functional improvement. The PPI group showed a significant decrease of the subjective instability. No procedure-related complications were reported. Conclusion This study suggests that DMTT is a viable option for PPI patients with patella alta. The outcome was comparable between PPI and OPI cases; however, decrease in subjective instability was significantly greater in PPI patients. Level of Evidence Level III, retrospective comparative study.

The effect of particle size on the in vivo degradation of poly(d,l-lactide-co-glycolide)/α-tricalcium phosphate micro- and nanocomposites.

This paper reports the effect of particle size within a resorbable composite on the in vivo degradation rate and host response. Resorbable composites based on poly(d,l-lactide-co-glycolide) (PLGA) reinforced with tricalcium phosphate (TCP) have shown suitable degradation, biological and mechanical properties for bone repair. Composites with nano-sized TCP particles degrade more homogenously in vitro than equivalent composites with micro-sized particles. In this study, PLGA and PLGA/TCP composites containing micro- or nano-sized α-TCP particles were implanted into an ovine distal femoral condyle defect and harvested at 6, 12, 18 and 24weeks. An intimate interface was observed between the new bone tissue and degrading implants. Visual scoring of histological images and semi-automated segmentation of X-ray images were used to quantify implant degradation and the growth of new bone tissue in the implant site. Bone growth into the implant site occurred at a similar rate for both composites and the PLGA control. However, the in vivo degradation rate of the nanocomposite was slower than that of the microcomposite and consequently more closely matched the rate of bone growth. For the first 6weeks, the rate of in vivo degradation matched that of in vitro degradation, but lagged significantly at longer time points. These results point to the potential use of ceramic particle size in controlling composite degradation whilst maintaining good bone formation. STATEMENT OF SIGNIFICANCE: This paper concerns degradable composites for orthopaedic application. The effect of particle size on implant degradation in vivo is not yet well characterised and these results give the first opportunity to directly compare in vitro and in vivo degradation rates for composites with micro- and nano-sized particles. This type of data is vital for the validation of models of composite degradation behaviour, which will lead to the design and manufacture of composites with a tailored, predictable degradation profile. The trainable segmentation tool can be used for future studies where X-rays of partially degraded implants (which have complicated greyscales and morphologies) need to be quantified without bias.

Evaluation of patello-femoral alignment by CT scans: interobserver reliability of several parameters.

Patello-femoral malalignment (PFM) is a common cause of disability often related to patello-femoral syndrome (PFS). Several causes have been taken into account; a proper diagnosis requires instrumental imaging and a methodical evaluation of different parameters. The aim of the present study was to identify the most reliable parameters for measuring patello-femoral and inferior limb alignment by CT. Twenty randomly selected patients suffering from PFS for a total of 40 knees were studied by static CT scans in order to assess patellar tilt, patellar displacement, patellar and trochlear morphology and inferior limb alignment. All known parameters were measured; the variability of the measurements between observers was evaluated by boxplots, Pearson's correlation coefficients, and infraclass correlation coefficient [ICC(2,1)] based on a two-way random effect model. Bland-Altman mean differences and 95 % limits of agreement were computed for each pair of measurements. Patellar tilt parameters appeared equally reliable; patellar displacement is best measured with BoTot that showed an ICC of 0.889; morphology is best measured with WibergTot, with an ICC of 0.862; lastly, for the inferior limb alignment parameters' analysis, FTV outperformed the others in terms of reliability. The present study allowed us to select a limited number of reliable parameters in the evaluation of patello-femoral and inferior limb alignment. The use of these parameters may also result in a more reliable comparison of studies on PFM and in a better evaluation of the treatment outcomes.

Late-diagnosed large osteochondral fracture of the lateral femoral condyle in an adolescent: a case report.

In this case report, we describe a large osteochondral fracture of the anterolateral femoral condyle in an adolescent athlete while dancing. At 3 months after the misdiagnosed injury, the condylar defect was covered by a layer of disorganized fibrous tissue rich in blood vessels. To achieve good repair, an accurate curettage of the fractured surfaces, a precise reduction, and a stable internal fixation of the fragments were performed. Two poly-L-lactic acid bioabsorbable screws were used to obtain appropriate compression. At the 2-year follow-up, the patient was asymptomatic and had resumed her previous dancing activity. An MRI scan showed no interruptions of the cartilage layer at the boundary with the healthy tissue, but cartilage thinning and extensive subchondral remodeling were detected.

Collagen fibre implant for tendon and ligament biological augmentation. In vivo study in an ovine model.

PURPOSE: Although most in vitro studies indicate that collagen is a suitable biomaterial for tendon and ligament tissue engineering, in vivo studies of implanted collagen for regeneration of these tissues are still lacking. The objectives of this study were the following: (1) to investigate the regeneration of the central third of the ovine patellar tendon using implants made of an open array of collagen fibres (reconstituted, extruded bovine collagen); and (2) to compare two collagen crosslinking chemistries: carbodiimide and carbodiimide associated with ethyleneglycoldiglycidylether. METHODS: Forty-eight Welsh Mountain sheep were operated on their right hind leg. The central third of patellar tendon was removed and substituted with carbodiimide (n = 16) and carbodiimide-ethyleneglycoldiglycidylether-crosslinked implants (n = 16). In the control group the defect was left empty (n = 16). The central third of contralateral unoperated tendons was used as positive controls. Half of the sheep in each group were killed at 3- and 6-month time points. After proper dissection, tendon sub-units (medial, central and lateral) were tested to failure (n = 6 for each group), whilst 2 non-dissected samples were used for histology. RESULTS: Both the implants had significantly lower stress to failure and modulus with respect to native tendon at both 3- and at 6-month time points. The implants did not statistically differ in stress to failure, whilst carbodiimide-crosslinked implants had significantly higher modulus than carbodiimide-ethyleneglycoldiglycidylether-crosslinked implants both at 3 and at 6 months. Histology showed carbodiimide-crosslinked implants to have a better integration with the native tendon than carbodiimide-ethyleneglycoldiglycidylether-crosslinked implants. Carbodiimide-crosslinked implants appeared partially resorbed and showed increased tissue ingrowth with respect to carbodiimide-ethyleneglycoldiglycidylether-crosslinked implants. CONCLUSIONS: To deliver collagen implants as an open array of fibres allows optimal tendon-implant integration and good ingrowth of regenerated tissue. In the present study the resorption rate of both the examined implants was too low due to the high level of crosslinking. This led to only minor substitution of the implant with regenerated tissue, which in turn produced a low-strength implanted region. Further studies are needed to find the right balance between strength and resorption rate of collagen fibres.

Arthroscopic knee cartilage repair with covered microfracture and bone marrow concentrate.

In recent years several single-stage cartilage repair approaches have been devised to treat focal cartilage lesions. These usually associate microfracture (MFX) and a coverage scaffold. We describe a novel arthroscopic technique that combines MFX, autologous bone marrow concentrate (BMC), and a protective scaffold. Bone marrow aspirate from the iliac crest is centrifuged to obtain BMC. The cartilage defect is debrided, MFX holes are created, and the final defect is measured by use of a bent K-wire. The scaffold is then shaped to match the defect, immersed in BMC, introduced into the joint with a grasper, and fixed in place with a mixture of fibrin glue and BMC. This technique aims to augment the original single-stage procedure with a number of mesenchymal stem cells and growth factors contained in the BMC, to increase the defect filling and the rate of hyaline-like cartilage regeneration. The procedure combining MFX, BMC, and a protective scaffold is inexpensive and reproducible and has already shown the ability to regenerate hyaline-like cartilage. Its use as an alternative to autologous chondrocyte implantation requires further investigation.

Matrix-induced autologous chondrocyte implantation (MACI) in the knee.

PURPOSE: Matrix-induced autologous chondrocyte implantation (MACI) has been in use for chondral defect repair since 2000, but to date, only little is known about its histological outcomes in the repair of knee cartilage defects. This prospective multicentre study aims to evaluate (1) the quality of the repair tissue obtained from biopsies taken during second-look arthroscopy and (2) the relationship between the histological outcome, the macroscopic appearance of the repair and the patients' functional status. METHODS: Thirty-three second-look core biopsies from 30 patients treated with MACI were analysed. At the time of biopsy, the surgeon reported the reason for the second-look arthroscopy, the quality of the repair tissue and the patient's functional status on a standardised form. Biopsies together with patient data were sent to our centre to undergo blind histological evaluation and data analysis. RESULTS: The median overall ICRS II histological score of the examined population was 57 (1st-3rd quartile 41-75). According to the ICRS cartilage repair assessment (CRA) arthroscopic evaluation, 10 biopsies (30%) were classified as normal, 17 (51%) as nearly normal, 4 (12%) as abnormal and 2 (6%) as severely abnormal. The histological outcome was not significantly related either to the macroscopic appearance of the lesion or to the patient's functional status at the time of biopsy. CONCLUSIONS: In the examined population, the macroscopic appearance of the repair tissue gave an overly favourable impression in comparison with the real histological composition of the tissue, which was possibly still maturing in many cases. The healing process after MACI needs to be better understood through a larger histological study, and a longer follow-up is needed to better clarify the relationship between histology and long-term functional status. LEVEL OF EVIDENCE: IV.

Extruded collagen fibres for tissue engineering applications: effect of crosslinking method on mechanical and biological properties.

Reconstituted collagen fibres are promising candidates for tendon and ligament tissue regeneration. The crosslinking procedure determines the fibres' mechanical properties, degradation rate, and cell-fibre interactions. We aimed to compare mechanical and biological properties of collagen fibres resulting from two different types of crosslinking chemistry based on 1-ethyl-3-(3-dimethyllaminopropyl)carbodiimide (EDC). Fibres were crosslinked with either EDC or with EDC and ethylene-glycol-diglycidyl-ether (EDC/EGDE). Single fibres were mechanically tested to failure and bundles of fibres were seeded with tendon fibroblasts (TFs) and cell attachment and proliferation were determined over 14 days in culture. Collagen type I and tenascin-C production were assessed by immunohistochemistry and dot-blotting. EDC chemistry resulted in fibres with average mechanical properties but the highest cell proliferation rate and matrix protein production. EDC/EGDE chemistry resulted in fibres with improved mechanical properties but with a lower biocompatibility profile. Both chemistries may provide useful structures for scaffolding regeneration of tendon and ligament tissue and will be evaluated for in vivo tendon regeneration in future experiments.

Distal realignment and patellar autologous chondrocyte implantation: mid-term results in a selected population.

The aim of this prospective observational study was to assess the 3-year clinical outcome of distal realignment and membrane-seeded autologous chondrocyte implantation (MACI) in selected patients with patellofemoral malalignment and large, isolated, patellar cartilage lesions. Twelve patients (14 knees; 6 females, 6 males; mean age 31 years) with Fulkerson type II patellofemoral malalignment (lateralized and tilted patella) and Outerbridge grade III-IV isolated patellar cartilage lesions were treated. All had tibial tuberosity and trochlear sulcus >20 mm on a preoperative CT scan and a cartilage defect >3 cm2. Patients with Outerbridge grade III-IV trochlear cartilage lesions, those with rheumatic, infective or neoplastic conditions, or ligament instability, diabetes or obesity and those aged >40 years were excluded. Follow-up was at 36 months. Patients were enrolled after diagnostic arthroscopy. Cartilage was harvested and sent for culture. After a mean period of 30 days (range 25-40) patients underwent transfer of the tibial tuberosity according to Fulkerson associated with a MACI procedure. Clinical assessment was performed with the Kujala, Lysholm, Tegner and Modified Cincinnati scores. The Patient Satisfaction Survey was administered at 36 months. Consistently improved knee function and activity levels were reflected by significantly increased Kujala, Lysholm, Tegner and Modified Cincinnati scores at 36 months. The significant clinical improvement support the value of associating distal realignment and autologous chondrocyte implantation in treating large, isolated, patellar cartilage lesions associated with patellofemoral malalignment.