What parameters affect knee function in patients with untreated cartilage defects: baseline data from the German Cartilage Registry

[The first decade of the DGOU's cartilage register-insights for clinical practice]

BACKGROUND

Registry data provide valuable epidemiological insights that help to further improve process and outcome quality in patient care. The German Cartilage Registry (KnorpelRegister DGOU) was established in 2013 as an instrument for quality assurance after surgical cartilage regenerative procedures on hip, knee and ankle joints.

DATA COLLECTION

Participation in the German Cartilage Registry is optional for hospitals and practices. Currently, more than 160 institutions in Germany, Austria and Switzerland participate in the data collection.

DATA COLLECTED AND INITIAL FINDINGS

The implementation of PROMs ("patient related outcome measurement"), as well as the recording of surgery-related influencing factors, enable a differentiated scientific analysis and represent a key quality feature of the registry. Initial analyses of the registry data have already provided clinically relevant findings for immediate patient care. For example, patients who underwent focal cartilage therapy prior to ACT show a clinically relevant, significantly worse outcome than patients who underwent primary ACT. First conclusions could also be drawn regarding the relevance of concomitant cartilage therapy. For example, in patients with focal cartilage damage of the medial knee joint compartment, registry data indicate that leg axis correction is indicated even in cases of mild deviation of the mechanical leg axis.

CONCLUSION

The data and findings obtained from the Cartilage Registry represent an important aspect of clinical care research and serve as a complement to well-designed, clinically prospective cohort studies, RCTs, and meta-analyses.

The Effect of Smoking on the Outcome of Matrix-Based Autologous Chondrocyte Implantation: Data from the German Cartilage Registry

Smoking is known to have various deleterious effects on health. However, it is not clear whether smoking negatively affects the postoperative outcome following matrix-based autologous cartilage implantation (MACI) in the knee. The purpose of this study was to evaluate the effect of smoking on the outcome of MACI in the knee. A total of 281 patients receiving MACI in the knee between 2015 and 2018 were registered in the German Cartilage Database. The cohort was divided into ex-smokers, smokers, and nonsmokers. Data regarding the Knee Injury and Osteoarthritis Outcome Score (KOOS), the numeric rating scale (NRS) for pain, and satisfaction with the outcome were analyzed and compared. Follow-ups were performed at 6, 12, and 24 months after surgery. Of the 281 patients, 225 (80.1%) were nonsmokers, 43 (15.3%) were smokers, and 13 (4.6%) were ex-smokers. The three groups were comparable with respect to age, sex, body mass index (BMI), height, defect size, the need for additional reconstruction of the subchondral bone defect, number of previous knee surgeries, and defect location. However, nonsmokers had a significantly lower weight as compared with smokers. Besides a significantly lower preoperative NRS of nonsmokers as compared with smokers, there were no significant differences between the three groups with respect to KOOS, NRS, and satisfaction at 6, 12, and 24 months of follow-ups. The present study of data retrieved from the German Cartilage Registry suggests that the smoking status does not influence the outcome of MACI in the knee.

Application Effect of Different Concentrations of Platelet-Rich Plasma Combined with Quadriceps Training on Cartilage Repair of Knee Osteoarthritis

We investigated the application effect of different concentrations of platelet-rich plasma (PRP) combined with quadriceps training on cartilage repair of knee osteoarthritis. Data of 37 patients with knee osteoarthritis (KOA) treated in our hospital (November 2019–February 2021) were retrospectively analyzed and the patients were divided into low concentration group (LCG) (n = 12), medium concentration group (MCG) (n = 12), and high concentration group (HCG) (n = 13) according to the order of admission. All patients received quadriceps training. Three groups above received knee injection of PRP, and the platelet concentrations were 1000–1400 × 10⁹/L, 1400–1800 × 10⁹/L, and 1800–2100 × 10⁹/L, respectively. Articular cartilage thickness of the medial and lateral femur, knee joint function scores, inflammatory factor levels, and matrix metalloproteinases (MMPs) levels were compared. After treatment, compared with the MCG and HCG, articular cartilage thickness of the medial and lateral femur of the diseased side in the LCG was obviously lower (P < 0.05). At 2 months after treatment (T₃), compared with the HCG, articular cartilage thickness of the medial and lateral femur of the diseased side in the MCG was obviously higher (P < 0.05), without remarkable difference in articular cartilage thickness of the medial and lateral femur of the healthy side among three groups (P > 0.05). After treatment, compared with the LCG, knee joint function scores of the MCG and HCG were obviously better (P < 0.001). Compared with the HCG, the knee function score at T₃ in the MCG was obviously better (P < 0.001). After treatment, compared with the LCG, inflammatory factor levels and levels of MMPs in the MCG and HCG were obviously lower (P < 0.05). Compared with the HCG, inflammatory factor levels and levels of MMPs at T₃ in the MCG were obviously lower (P < 0.05). PRP combined with quadriceps training can accelerate cartilage repair of patients with KOA and reduce inflammatory factor levels and levels of MMPs, but the treatment effect of PRP depends on platelet concentration, with the best range of 1400–1800 × 10⁹/L. Too high or too low platelet concentrations will affect recovery of knee function.

Effect of Previous Knee Surgery on Clinical Outcome After ACI for Knee Cartilage Defects: A Propensity Score-Matched Study Based on the German Cartilage Registry (KnorpelRegister DGOU)

BACKGROUND

Autologous chondrocyte implantation (ACI) is an established procedure for the treatment of cartilage damage in the knee joint. At present, it is still unclear how previous surgery influences outcome after ACI.

PURPOSE

To evaluate the effect of previous knee surgery related or nonrelated to the treated cartilage defect on clinical outcome after ACI for knee cartilage defects.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

An overall 730 patients with ACI who underwent previous unspecific knee surgery, whether related to the defect being currently treated or not, were identified from a cohort of 5961 patients registered in the German Cartilage Registry. Propensity score matching was used to match these patients to 690 patients with analogous characteristics but without previous surgery. Subsequently, 317 patients with previously failed cartilage treatment at the defect site were identified and compared with a matched collective of 254 patients without previous cartilage treatment. In a subgroup analysis, the type of previous cartilage surgery was additionally investigated. Outcome was evaluated by Knee injury and Osteoarthritis Outcome Score (KOOS), visual analog scale for pain, rate of reintervention, and patient satisfaction up to 36 months. A chi-square test was used to compare categorial variables and an unpaired t test to compare continuous variables.

RESULTS

Patients with previous knee surgery not related to the cartilage defect showed a lower KOOS at 6 months (68.3 vs 70.8; P = .026), while patients with previous cartilage surgery showed significantly lower KOOS values at all follow-up time points when compared with patients without any previous knee or cartilage surgery (all P < .05). A comparison of KOOS values in patients with previous therapy at the cartilage defect with ACI versus bone marrow stimulation did not show any significant differences at any follow-up.

CONCLUSION

Previously failed cartilage treatment at the defect site represents a negative prognostic factor up to 3 years after ACI. However, this influence appears to be independent of the type of previous treatment at the defect site and applies equally to failed bone marrow stimulation as well as previous ACI. In contrast, a negative effect of previous surgery to the knee unrelated to the cartilage defect could not be shown in the 3-year follow-up.

Does Gender Influence Outcome in Cartilage Repair Surgery? An Analysis of 4,968 Consecutive Patients from the German Cartilage Registry (Knorpel Register DGOU)

The goal was to examine gender differences of patient characteristics and outcome after cartilage repair based on a collective of nearly 5,000 patients. Patient characteristics, accompanying therapies, and outcome (Knee Injury and Osteoarthritis Outcome Score [KOOS], reoperations, patient satisfaction) of 4,986 patients of the German cartilage register DGOU were assessed by t test for possible gender differences. P values <0.05 were considered statistically significant. Women were older than men (38.07 ± 12.54 vs. 26.94 ± 12.394 years, P = 0.002), more often preoperated (0.30 ± 0.63 vs. 0.24 ± 0.55, P = 0.001), and had a longer symptom duration (25.22 ± 41.20 vs. 20.67 ± 35.32 months, P < 0.001). Men had greater mean leg axis malalignment than women (3.24° ± 3.26° vs. 2.67° ± 3.06°, P < 0.001), less favorable meniscal status (P = 0.001), worse defect stage (P = 0.006), and a more severely damaged corresponding articular surface (P = 0.042). At baseline (59.84 ± 17.49 vs. 52.10 ± 17.77, P < 0.001), after 6 months (72.83 ± 15.56 vs. 66.56 ± 17.66, P < 0.001), after 12 months (77.88 ± 15.95 vs. 73.07 ± 18.12, P < 0.001), and after 24 months (79.311 ± 15.94 vs. 74.39 ± 18.81, P < 0.001), men had better absolute KOOS values, but women had better relative KOOS increases 6 months (14.59 ± 17.31 vs. 12.49 ± 16.3, P = 0.005) as well as 12 months postoperatively (20.27 ± 18.6 vs. 17.34 ± 17.79, P = 0.001) compared with preoperatively, although 12 and 24 months postoperatively they were subjectively less satisfied with the outcome (P < 0.001) and had a higher reintervention rate at 24 months (0.17 ± 0.38 vs. 0.12 ± 0.33, P = 0.008). In summary, the present work shows specific gender differences in terms of patient characteristics, defect etiology, defect localization, concomitant therapy, and the choice of cartilage repair procedure. Unexpectedly, contrary to the established scientific opinion, it could be demonstrated that women show relatively better postoperative KOOS increases, despite a higher revision rate and higher subjective dissatisfaction.

BioCartilage augmentation of marrow stimulation procedures for cartilage defects of the knee: Two-year clinical outcomes

BACKGROUND

The present study evaluated short-term outcomes of microfracture augmented with micronized allograft cartilage matrix (BioCartilage) and platelet-rich plasma (PRP) for symptomatic focal femoral condyle or trochlea cartilage defects.

METHODS

Patients who underwent microfracture augmented with BioCartilage and PRP for isolated contained chondral defects were evaluated. Magnetic resonance imaging (MRI) was performed at one year postoperatively. Two-year postoperative outcomes included patient-reported outcome measures (PROMs) and rates of return-to-work and return-to-sport.

RESULTS

Mean age of the 10 patients who completed the study was 39.7 years (range, 19-66 years), and five (50%) were female. Mean post-debridement defect size of the five femoral condyle and five trochlea defects was 2.4 cm² (range, 0.7-5.0 cm²). One-year postoperative MRI analysis demonstrated that two chondral lesions were <50% filled, four sites were >50% filled, two sites were completely filled, and two sites had hypertrophied. Patients experienced improvements in three PROMs at six months, one year, and two years postoperatively (p < 0.01). Postoperative Marx Activity scores revealed no decrease in activity level compared to baseline preoperatively. Nine patients (90%) returned to their pre-injury level of work by one year postoperatively and remained at that level through two years postoperatively.

CONCLUSIONS

Our findings suggest that small, contained focal chondral injuries in the femoral condyle and trochlea treated with a marrow stimulation procedure augmented with BioCartilage and PRP are associated with significant improvements in patient-reported outcomes at two years postoperatively. Further studies are needed to evaluate the long-term durability and imaging characteristics of this intervention. Level of evidence Therapeutic Level IV.

Coronavirus disease 2019 pandemic: should we delay cartilage regenerative procedures and accept the consequences, or can we find a new normality?

The COVID-19 pandemic changed elective surgery routine. During the initial spread of the novel coronavirus, elective surgery has been stopped and only emergency and trauma and oncologic procedures were allowed. Following the decrease of the contagion curve, elective surgery is slowly being recovered. The hospitals should create a pre-hospitalization path to identify possible infected patient and further postpone surgery. In this setting, cartilage repair surgery should not be neglected, because this could potentially lead to an increase of patients needing major joint replacement surgery.

Autologous costal chondral transplantation and costa-derived chondrocyte implantation: emerging surgical techniques

It is a great challenge to cure symptomatic lesions and considerable defects of hyaline cartilage due to its complex structure and poor self-repair capacity. If left untreated, unmatured degeneration will cause significant complications. Surgical intervention to repair cartilage may prevent progressive joint degeneration. A series of surgical techniques, including biological augmentation, microfracture and bone marrow stimulation, autologous chondrocyte implantation (ACI), and allogenic and autogenic chondral/osteochondral transplantation, have been used for various indications. However, the limited repairing capacity and the potential pitfalls of these techniques cannot be ignored. Increasing evidence has shown promising outcomes from ACI and cartilage transplantation. Nevertheless, the morbidity of autologous donor sites and limited resource of allogeneic bone have considerably restricted the wide application of these surgical techniques. Costal cartilage, which preserves permanent chondrocytes and the natural osteochondral junction, is an ideal candidate for the restoration of cartilage defects. Several in vitro and in vivo studies have shown good performance of costal cartilage transplantation. Although costal cartilage is a classic donor in plastic and cosmetic surgery, it is rarely used in skeletal cartilage restoration. In this review, we introduce the fundamental properties of costal cartilage and summarize costa-derived chondrocyte implantation and costal chondral/osteochondral transplantation. We will also discuss the pitfalls and pearls of costal cartilage transplantation. Costal chondral/osteochondral transplantation and costa-based chondrocytotherapy might be up-and-coming surgical techniques for recalcitrant cartilage lesions.