Purpose

Osteochondritis dissecans (OCD) of the knee is a rare, invalidating disorder in which subchondral bone detaches, leading to an osteochondral fragment that can become unstable and progress into a loose body. The exact etiology is still unknown, although several biological and mechanical factors are described. We aim to give insight into epidemiological data of patients affected by OCD of the knee and to identify possible factors contributing to the etiology of this disorder.

Methods and Materials

A total of 222 patients (250 knees) affected by OCD were included in the UMC Utrecht Knee Registry (2005-2020) and retrospectively analyzed. Patient demographics were extracted from the medical records. Location and ICRS grade (I-IV) of OCD were assessed using MRI. If available, a full-leg standing radiograph was used to asses (mal)alignment.

Results

A total of 256 OCD lesions were identified in 250 knees, 64.4% on the medial femur condyle (MFC), 28.9% lateral femur condyle (LFC), 4.3% trochlea, 2.3% patella and 1.2% lateral tibia plateau. The male:female ratio was 1.3:1. A very high percentage of patients (71.2%, n=158) practiced sports, of which 70.3% (n=111) practiced high-impact sports. The location of OCD and the leg alignment (n=79) were statistically significantly correlated, MFC lesions had more varus than valgus alignment (40.0% vs 7.0%) and patients with LFC lesions had more valgus than varus alignment (46.2% vs 11.5%) (p=0.000). The mean ICRS grade was higher in patients reporting trauma prior to onset of symptoms (p=0.000).

Conclusion

This study provides insight into epidemiological data of 222 patients affected by OCD of the knee. There is an association between OCD of the MFC and varus malalignment and between OCD of the LFC and valgus malalignment. This, in combination with the high percentage of patients practicing (high-impact) sports, suggests an important role for mechanical overload in the pathogenesis of OCD.

Purpose

The patellofemoral joint can be a particularly challenging environment for treating chondral defects, due to the high loads acting on its surface. Among the different available surgical options for treatment of chondral defects, the single-stage AMIC procedure was performed, which uses a collagen I/III membrane to enhance bone-marrow stimulation. In order to ascertain the effectiveness of AMIC in treating chondral lesions, an ongoing registry has been established in order to record patient data and outcomes. Here, we evaluated the effectiveness of AMIC for patellar chondral lesions.

Methods and Materials

All data were retrieved from a multisite, prospective registry that recorded demographic data and outcomes for patients who had undergone surgical repair of patellar, chondral defects. In total, 63 patients from 5 surgeons were included in the analysis. All defects had been classified as Outerbridge III or IV and were treated with the 1-stage AMIC procedure.

Results

The mean lesion size was 3.2 ± 1.6 cm2. The most common surgical approach was mini-open while the most common fixation was via fibrin glue. Follow-up visits were conducted as part of the standard of care at each site. The figure below shows a significant improvement in the Lysholm

follow-up up to 10 years. Likewise, a significant decrease in pain VAS was noted at all post-operative timepoints (p<0.01). With regard to physical activity, the sports-recreation score showed a significant improvement, and at the latest follow-up was still significantly higher than the pre-operative score (P<0.05).

Conclusion

The data from this study demonstrate that the 1-stage AMIC procedure is an effective treatment for retropatellar cartilage defects, and provides positive results, as demonstrated by decreased pain and improved function of the patients. Importantly, these improvements were maintained up to 10 years after surgery.

Purpose

Cell-free biomaterials have been developed to restore defects of the articular surface, avoiding the problems related to cell-based procedures. Among these, an osteochondral scaffold made of type I collagen and hydroxyapatite has been introduced in the clinical practice. Aim of this study was to evaluate the clinical outcome after the implantation of this osteochondral scaffold for the treatment of isolated knee lesions.

Methods and Materials

One hundred and ten patients (80 men, 30 women), affected by grade III-IV acute or chronic chondral/osteochondral lesions or osteochondritis dissecans (OCD) lesions were consecutively treated. The mean age was 27.5±10.7 years, the mean lesion size was 3.0±1.9 cm². Fifty-five patients had undergone previous surgeries, whereas minor concurrent procedures (i.e. partial meniscectomy) were necessary in 14 cases. Patients were prospectively followed at baseline and at 6, 12, and 24 months for the primary outcome, the IKDC Subjective Score, and secondary outcomes including the IKDC objective score and Tegner score.

Results

All the scores significantly improved: IKDC score increased from the baseline to 12 months of follow-up (44.8±16.1 to 68.4±18.4, p<0.005), with a slight further increase up to 24 months’ follow-up (75.3±17.1). The Tegner score also increased significantly, but the pre-injury activity level did not recover. Patients who were operated for the first time had basal IKDC values of 47.4±14.4 and improved to 79.6±14.1, while patients with previous surgery passed from 41.9±16.8 to 71.3±18.9. Thirty-seven patients reported an adverse event (6% major) after the procedure, and 3 were considered surgical failures.

Conclusion

This one-step cell-free biomimetic approach developed to favor osteochondral tissue regeneration is effective in treating isolated knee lesions, leading to a significant clinical improvement, with few failures and complications at short-term follow-up.

Purpose

To identify whether retro-tubercle opening-wedge high tibial osteotomy (RT-OWHTO) produces more favorable radiographic outcomes on patellofemoral joint alignment and clinical outcomes than supra-tubercle opening-wedge high tibial osteotomy (ST-OWHTO).

Methods and Materials

From January 2017 to July 2018, patients who underwent biplanar OWHTO were allocated to 1 of 2 groups (ST-OWHTO and RT-OWHTO). Plain radiographs and computed tomography were used to analyze patellofemoral alignment and other radiologic parameters representing osteotomy configurations (Figure 1). Clinical outcomes were assessed using American Knee Society Score and Western Ontario and McMaster Universities
Osteoarthritis Index.

Results

In total, 50 knees that underwent ST-OWHTO and 44 knees that underwent RT-OWHTO were enrolled. Patellar height was significantly decreased only after ST-OWHTO (Caton-Deschamps ratio: p = .007; Blackburne-Peel ratio: p = .012). Patellar tilt angle was decreased in both groups (p =.009 and .004, respectively). Postoperative posterior tibial slope (PTS) (p = .013), PTS (Δ) (P < .001), retro-tuberosity gap distance (p = .001), and retro-tuberosity tip distance (p = .001) were significantly larger in RT-OWHTO. Retro-tuberosity tip distance was significantly correlated with retro-tuberosity gap distance (p =.002), thickness of second plane osteotomy fragment (p =.027), and anterior osteotomy ratio (p =.031) in ST-OWHTO. In RT-OWHTO, it was significantly correlated with PTS (Δ) (P < .001), retro-tuberosity gap distance (P < .001), and sagittal angle of bi-planar osteotomy (p = .005). There were 2 cases of tibial tuberosity fracture, 9 cases of delayed union on second plane osteotomy and 5 cases of tuberosity protrusion in RT-OWHTO (Figure 2).

Conclusion

Although the RT-OWHTO technique maintains patellofemoral joint alignment, no difference in clinical outcome was detected. The RT-OWHTO has increased risk of tuberosity fracture, delayed union, and prominent tibial tuberosity. The surgeon should consider these negative aspects of the technique and consider adjusting additional stabilization.

Purpose

The purpose of this study was to develop preventive strategies by identifying factors that affect LHFs. We hypothesized that (1) each LHF type would have different affecting factors and that (2) specific operative strategies that can contribute to the prevention of each LHF type can be developed.

Methods and Materials

We retrospectively analyzed 261 consecutive knees treated with biplanar OWHTO between March 2014 and December 2016. A total of 66 knees were diagnosed with LHF and subclassified into types I, II, III, and I-variant. Perioperative radiological variables that can affect LHFs were measured and divided into two categories, determined and modifiable (Figure 1). A regression model was developed, and subgroup analyses were performed between the non-LHF group and each LHF group. The interval change of the weight-bearing line (WBL) ratio between postoperative 2 weeks and 1 year was performed for each LHF type.

Results

Every LHF types consist of several determined and modifiable factors. Type I LHF was possible to prevent by sufficient retro-tubercular thickness. For type II, thicker lateral distal fragment thickness and larger osteotomy-condylar angle that means higher starting point were important. For type III and I-variant, thicker lateral proximal fragment thickness and smaller retro-tubercular angle were important. The WBL ratio was decreased in type I LHF (p<0.001) and increased in type II (p=0.001) and I-variant (p=0.006) in serial assessment (Figure 2).

Conclusion

Unmodifiable and modifiable factors for the development of LHFs after OWHTO differ among LHF types. To prevent LHFs, the causes of each LHF must be identified, the patient’s specific geometry must be considered in the preoperative planning, and the surgical technique must be modified according to the modifiable factors. In addition, during the rehabilitation period after OWHTO, specific caution and closed observation are necessary for alignment changes related to each LHF type.

Purpose

Bone marrow derived mesenchymal stem cell transplantation is a novel surgical technique in the management of osteochondral defects, with the potential fro cartilage regeneration. The aim of this study was to demonstrate the 2 year outcomes of this intervention.

Methods and Materials

114 patients between the ages of 15-55 who had MRI diagnosed full thickness osteochondral defects in the knee were included. Patients were prospectively reviewed at 6, 12 and 24 months with a repeat MRI scan at 2 years. Visual analogue score (VAS), Cincinatti and EQ5D (tto, VAS) were noted at each time point. Linear regression and paired t-tests were utilised for data analyses.

Results

110 patients were included in the analysis with 4 patients lost to follow-up. The average age of patients was 29 (15-50), 75 males and 35 females. Table 1 demonstrates significant improvement in outcome scores in all outcomes except the EQ-5D at 2 years.

Graph 1 depicts improved outcome scores at each interval . Age and size of defect were independent risk factors for poor outcomes with those under 30 and with defects smaller than 400mm² having significant improvements in their VAS, Cincinnati, and EQ VAS scores (P<0.05) at 2 years as opposed to older patients and those with larger defects. MR imaging indicating successful graft incorporation was associated with significant improvement in all outcome scores P<0.05 with 79% of patients demonstrating more than 50% regeneration of hyaline like cartilage.

Conclusion

This study is the first to demonstrate clinical and radiological improvement in those patients undergoing surgery with bone marrow derived stem cells at 2 years for osteochondral defects around the knee.

Purpose

Autologous Matrix Induced Chondrogenesis (AMIC) is a well-established treatment for full-thickness cartilage defects. The purpose of this study was to evaluate the long term clinical outcomes following repair, via AMIC procedure, of chondral defects of the knee.

Methods and Materials

A multi-site prospective registry recorded demographic data and outcomes for patients treated for repair of chondral defects. In total 131 patients were included in the study. Lysholm, KOOS and VAS-pain were used for outcome analysis. The average age of patients was 36.6±11.7 years. The mean body weight was 80.0±16.8 kg, with a mean height 176.3 ± 7.9 cm, and the mean defect size 3.3±1.8 cm2. Defects were classified as grade III / IV according to ICRS classification. A repeated measures ANOVA was used to compare outcomes across all time points.

Results

The median follow-up time for the patients in this cohort was 4.56 ± 2.92 years. Significant improvement (p<0.001) of all scores was observed at 1-2 years after AMIC and improved values were notable up to 7 years postoperatively. The mean preoperative Lysholm score was 46.9 (± 19.7). At the 1-2 year follow-up, a significant increase of Lysholm score mean values was noted (83.1 ± 14.0) with maintenance of the favorable outcome during follow up at 7 years: (78.6 ± 17.1). Similarly, The KOOS score also showed a significant improvement of the postoperative values compared to the preoperative data. The mean preoperative VAS was 5.7 ± 1.8 and this had significantly decreased to. 2.5 ± 2.1 at the 7 years follow up. Age, gender and defect size did not have a significant effect on the outcomes.

Conclusion

AMIC is an effective method of treating chondral defects of the knee and leads to reliably favorable results up to 7 years post-operatively.

Purpose

Osteochondritis dissecans (OCD) is a disease of the entire osteochondral unit affecting young and active patients. In case of unstable and unfixable fragments, reconstructive cartilage procedures are a viable solution. During recent years, osteochondral scaffolds were introduced in clinical practice to address osteochondral pathologies, including knee OCD. The aim of this study is to evaluate long-term results offered by the implantation of a nanostructured biomimetic collagen-hydroxyapatite construct for the treatment of OCD of the knee.

Methods and Materials

Twenty-seven patients (19 men, 8 women; mean age, 25.5 ± 7.7 years) were treated for symptomatic unfixable OCD lesions International Cartilage Repair Society (ICRS) grade 3 to 4 with a mean size of 3.4 ± 2.2 cm². All patients were prospectively evaluated at 2, 5, and at minimum 10 years follow-up (average 12 years) with IKDC scores, EQ-VAS, and Tegner score. Failures were also documented.

Results

A statistically significant improvement in all clinical scores was observed from baseline evaluation to 24 months and remained stable at the final follow-up (mean 148 ± 13.8 months). The mean IKDC subjective score improved from 48.4 ± 17.8 to 82.2 ± 12.2 at 2 years (p < 0.0005), and it then remained stable up to 12 years postoperatively (80.0 ± 13.5, p < 0.0005). EQ-VAS and Tegner scores presented similar trends. There were no clinical or surgical failures.

Conclusion

The biomimetic scaffold implantation is a valid treatment option for unfixable knee OCD lesions. The clinical improvement obtained is significant and stable, with good results maintained for up to long term follow-up.

Purpose

Cartilage lesions of the patellofemoral joint are a challenging condition for orthopedic surgeons. Hyaluronan-based matrix assisted autologous chondrocyte transplantation (MACT) seems to offer significant improvement in the short and mid-term follow-up. The aim of this prospective study was to analyze the long-term results of MACT technique to address patellofemoral cartilage lesions.

Methods and Materials

A total of 38 patients (23 men, 15 women) with full-thickness patellofemoral chondral lesions were treated with a hyaluronan-based MACT and followed prospectively for a minimum follow-up of 15 years (mean 17.8±1.7 years). Twenty-four lesions were located on patella, 10 on trochlea, and 4 patients had both patellar and trochlear defects. Results were evaluated using International Knee Documentation Committee (IKDC) subjective, EuroQol visual analogue scale (EQ-VAS) and Tegner scores.

Results

A statistically significant improvement in all scores was observed up to the final follow-up compared to the preoperative level. The IKDC subjective score improved from 35.3±12.8 at baseline to 75.5±18.9 at 5 years (P<0.0005), then remained stable at 10 years (77.7±19.8), while decreased (not significant) at the final follow-up (68.6±22.6). The mean of EQ-VAS score increased from 54.2±18.1 to 82,6±12.1 (P<0.0009) at 5 years and then remained stable up to 15 years (82.9±14) (P<0.0005). Finally, the sport activity level evaluated with the Tegner score improved significantly from the preoperative score of 1.8±1.1 to the final evaluation score of 3.5±1.7, even if it remained lower with respect to activity level before onset of symptoms (6.4±1.8). Trochlear lesions showed better results compared with patellar lesions (IKDC at 15 years: 80.2±22.9 vs 61.8±21.7, respectively). Three failures were reported: 2 patients required a total knee arthroplasty, and one patient received a scaffold-procedure).

Conclusion

Hyaluronan-based MACT showed positive clinical results and a low failure rate in patients with patellofemoral cartilage lesions up to long-term follow-up. Better results were observed in patients with isolated throclear lesions.

Purpose

Describe the cartilage defects, patient characteristics, and clinical outcomes for adult patients treated with MACI^® (autologous cultured chondrocytes on porcine collagen membrane) for cartilage restoration to the patella.

Methods and Materials

Following institutional review board approval, data were collected for patients treated by 10 surgeons between Jan 2017 and Sep 2019. Patient demographics, cartilage defect characteristics, and concomitant surgical procedures were summarized with descriptive statistics. All patient demographics and cartilage defect characteristics were entered in the database although collection of final clinical and patient reported outcomes is ongoing.

Results

A total of 136 patients that received MACI treatment to the patella were available for analysis. The population was predominantly female (68%), mean age of 32 years, and BMI of 26.4 kg/m². A majority of patients had undergone multiple previous knee surgeries. The most common prior surgical procedures, aside from chondroplasty/abrasion arthroplasty done at the time of the cartilage biopsy, were cartilage debridement (65%), loose body removal (15%), and meniscectomy (13.2%).

The average MACI treated patellar defect was 4.6 cm². Approximately 20% of patients had a bipolar trochlear defect treated with MACI, and 17% of patients also had a MFC defect treated with MACI. The mean non-patella defect size was 4.4 cm². At the time of MACI implantation, 46% of patients had a concomitant tibial tubercle osteotomy and 32% underwent medial patellofemoral ligament repair/reconstruction.

Two patients where the largest treated defect was the patella were considered treatment failures due to graft failure and requirement for major revision (both patients received osteochondral allografts with concomitant TTO within 2 years of MACI surgery).

Conclusion

This is the first multicenter report of patient and cartilage defect characteristics for patients receiving MACI implantation in the patella. Clinical and patient-reported outcomes will be included in the final presentation.