MOSAICPLASTY TECHNIQUES IN THE TREATMENT OF OSTEOCHONDRAL INJURIES

Introduction : Articular cartilage damage is quite a common problem within the general population, especially in the younger and more athletic populations. These defects, if left untreated, would lead to post-traumatic osteoarthritis. Taking into consideration the high frequency and socioeconomic burden of osteoarthritis, the treatment of osteochondral lesions presents a unique challenge for surgeons. Materials/Methods: Several hypotheses were formulated to discover whether mosaicplasty could be used in order to successfully treat osteochondral lesions. Furthermore, open mini and arthroscopic surgery were tested to determine whether they could achieve the same result as mosaicplasty. A sample of 45 patients from the general population volunteered for the study, of whom 13 patients underwent open mosaicplasty, 17 mini-open and 15 patients arthroscopic mosaicplasty. Assessment of the knee articular cartilage reconstruction was done during each visit, utilising Lysholm and the VAS scale. A histological examination was also performed. Results : A significant difference was observed be-tween pre-and post-surgical Lysholm score, as well as be-tween pre-and post-surgical VAS score. Additionally, histological analysis confirmed the success of osteochondral autograft transfer and integration into the recipient’s knee. Conclusion : The study demonstrated that several mosaicplasty techniques could be used in articular cartilage reconstruction. Moreover, the histological examination further confirmed the viability of the autograft.


INTRODUCTION
Osteochondral lesions, while occurring regularly, present an unremitting challenge to surgeons.The reason for this is that the therapy should not only consider anatomical reconstruction but also the prevention of osteoarthritis as a long-term complication and provide adequate pain relief [1].This is particularly true for younger patients, for whom hemi or total knee arthroplasty is rarely advised [2,3,4,5,6].Using multiple cylinders, mosaicplasty allows the restoration of the contour of the affected surface thus restoring the integrity of the joint surface.
Treatment of osteochondral lesions through mosaicplasty is shown to be an appropriate, cost-efficient method, which could restore the articular cartilage to its original condition in patients for whom arthroplasty is otherwise contra-indicated [2,7,8,9].Furthermore, mosaicplasty could be performed as a single-stage procedure as an open, semi-open or arthroscopic surgery.

MATERIALS AND METHODS
Clinical research was conducted at the Clinic of Orthopaedics and Traumatology of University Hospital Pleven "Dr Georgy Stranski" from 2010 to 2018.
A sample of 45 patients (27 males and 18 females, mean age 37 ± 10 years) from the general population volunteered for the study, of whom 13 patients were selected to undergo open mosaicplasty, 17 mini-open and 15 patients to undergo arthroscopic mosaicplasty.
Initially, each study began with a pre-operative assessment at the first meeting at the hospital (Table 1).After surgery, patients received follow ups several more times.
The assessment of the successfulness of the knee articular cartilage reconstruction was done during each visit utilising the Lysholm scale [10,11] and the Verbal Analogue Scale (VAS) scale [12].
Ethical approval for the study was granted by the Medical University -Pleven Research Department.Informed consent was obtained from all individual participants included in the study, and all participants were provided with correct and adequate information to take part in the study.Furthermore, patients were informed about the possible necessity of taking a graft from the contralateral knee.All surgeries were performed either under spinal or full anaesthesia, and all patients underwent prophylaxis for pulmonary embolism with low molecular weight heparin (Fraxiparine) 0.6 ml and broad-spectrum antibiotic.At the start of the operation, a diagnostic arthroscopy was performed.The default choice for all patients was to undergo the arthroscopic method of operation.Depending on the lesion size and localisation, the decision to continue with arthroscopic or to transform into mini-open or open surgery was made peri-operatively.

MOSAICPLASTY TECHNIQUES IN THE TREAT-MENT OF OSTEOCHONDRAL INJURIES
Anteromedial and anterolateral portals were used for arthroscopic operation, whereas medial parapatellar access was used during open mosaicplasty.We propose using a spinal needle percutaneously to the joint to choose the initial right access to the joint and for the correct orientation of the instruments.Furthermore, it is recommended to make vertical incisions, which will simplify the procedure of acquiring grafts.
After access to the joint, the defects were localised and probed.The length and depth of the cartilage lesions were then measured.Debridement of all damaged, free or unstable cartilage was performed, followed by resection, in order to achieve stable and healthy cartilage edges.The floor of the defects was also prepared with burs until subchondral bone could have been seen.After assessment of the number of chondral cylinders required, the OAT--reconstruction (Arithrex, osteo-chondral autograft transfer system) with a diameter of 4, 6 or 8 mm was used to acquire cylindrical osteochondral grafts from the periphery of medial patella-femoral groove.The aim was to take grafts of at least 6 mm.When restoring femoral defects, we preferred in our study to take grafts from the medial and lateral periphery patellar surface of the femur.From the studies concerning contact pressure on the retro-patellar surface, it known that average contact pressure is higher on the lateral side of the femoral condyle than the medial.Thus, the peripheral area of the medial patellofemoral joint was the first choice donor site for grafts.Furthermore, the most distal part of the lateral femoral condyle, above the terminal sul-cus, could be used as a donor area.Donor cylinders should be acquired at no less than 2 -3 mm from each other.Otherwise, tunnels may cross, and it will lead to a deficiency of subchondral bone in the graft.
A step-by-step procedure was used to fill in the defects with press-fit to recipient tunnels, which were prepared in advance at the site of chondral defect.Furthermore, a table of additional operational procedures that were performed during surgical operations is supplied (Table 2).

Rehabilitation
All groups of patients have followed the same rehabilitation protocol.Knee braces, which allow motion from 0 to 90 degrees, were installed on the day after the operation, and patients were instructed to begin rehabilitation within a determined degree of range of movement (0 -90 degrees).The patients were encouraged to perform isometric quadriceps exercises.The main focus of early rehabilitation was to restore the range of movement and to decrease post-operational oedema.Patients were, however, not allowed to weight bear on the operated knee for the first 6 weeks and were instructed to use crutches when walking using the toe-touch technique.This was done to allow the integration of allografts into recipient tunnels.Subsequently, 6 weeks post-operation, patients were allowed to progressively bear weight on the operated knee on the con-

ACL plastics 1
Plica resection 1 dition of satisfactory x-ray findings and lack of subjective complaints.After 6 months, patients were permitted to return to full activity, including sports activity.

RESULTS
Statistical analysis was performed with Statistical Package for the Social Sciences (SPSS Inc., Chicago, Illinois, USA) and Microsoft Excel [14].
According to the results from a study, the medial femoral condyle was affected in more than 80% of operated patients, with the remaining 20% being the lateral condyle (p <0.01).
More than 1/3 of patients (18; 40%) correlated their disease with previous history of trauma.Osteochondritis dissecans was found in 18 (40%) of patients, and in the other 9 cases (20%), the cause was unknown.An absolute majority of chondral defects were located on the medial femoral condyle (89%), and in the rest cases, the lateral femoral condyle was affected.
From 45 patients, partial meniscectomy was performed in 17 patients, ACL reconstruction in 7 patients, lateral release procedure in 3 patients, free body removal in 2 patients and 1 patient plicae resection, respectively.
The average time of surgery was recorded to be around 60 ± 15 minutes.
All patients were with lesion through the subchondral bone (ICRS -4).
The average history of complaints was 9.5 months.Pre-operative Lysholm score was 43.6 (from 18 -61).Post-operative Lysholm score increased to an average of 93.5 (from 74 -100), which is statistically significant compared to an average pre-operative score of 43.6 (p = 0.001).In 40 patients (91.4%) received excellent or good outcomes, with restored joint function, and patient have returned to normal daily life activities.The average result was received with 5 patients (8.6%).

DISCUSSION
Surgical treatment of articular cartilage requires special caution due to the absence of a direct blood supply, lymphatics and nerves, relying solely on synovial fluid nourishment [3,15,16,17,18] .
From the literature perspective, mosaicplasty provides very good results, ranging from 72% to 92%.According to Versier and Dubrana [19], factors that provide a better prognosis were reported as follows: lesions on medial condyle, osteochondritis desiccans, deep, small lesions and the shortest possible surgical time.The results of this study, therefore, also support the findings of Versier and Dubrana [19].
The Lysholm score has been reported to be used in numerous studies regarding cartilage surgery, including mosaicplasty.Furthermore, Briggs et al. 2006, have proved that the Lysholm score has an acceptable test-retest reliability, floor and ceiling effects, criterion validity, construct validity, and accurately records responsiveness to change [11].Moreover, the Lysholm score is easy to understand and complete for patients, which is important for the general population.Hence, the Lysholm score was used in this study and confirmed that mosaic grafting could be used to restore the cartilaginous surface.Additionally, this study has found that all 3 surgical techniques provide a similar Lysholm score, meaning all 3 surgical techniques could be applied in the management of osteochondral lesions.
The results of this study confirms that mosaicplasty could be used for the treatment of osteochondral lesions of the knee [20].Furthermore, our study has found that all 3 surgical techniques could be used to provide long-term pain and functional relief with the same result.
However, in the opinion of the author, arthroscopic procedures should be used initially or at least attempted.Although not measured in the present study, after the arthroscopy procedure, patients reported feeling less pain immediately after surgery.This was noted to be in contrast with patients who had undergone mini or open surgery instead.
Furthermore, a study has compared patients with an excellent outcome and those with a good or poor outcome.It was found that patients with a poor outcome had a significantly longer duration of pre-operative symptoms (~23 months compared with ~7.5 months in those with an excellent outcome).Additionally, the two subgroups also differed in age.
A comparative analysis of patients under 45 years of age and those over 45 years of age furthermore revealed a significant difference in the final Lysholm score (92.3 in the under -45 years of age and 87.1 in the other subgroup).
Histological analysis of 7 patients also confirmed the successful osteochondral autograft transfer and their integration into the recipient knee (Fig. 4, Fig. 5).Nevertheless, fibrous cartilage was found in 2 patients, with both reporting the same Lysholm score, we can, therefore, assume that histological findings would be true and similar in the other patients with an equal score.Furthermore, it was found that in patients who received 6 or more grafts, the average Lysholm score (V4) was 84.7 compared to patients who only received up to 3 grafts (V4 was 93.4; p = 0.007).As such, we may conclude that mosaicplasty demonstrates certain benefits, such as being a low cost and efficient procedure, which could be used to reconstruct normal hyaline cartilage (Fig. 5).This was proven by histology (Fig. 4) and may be performed as a single surgical procedure [21].
The disadvantage of the mosaicplasty technique is the issue of the donor site morbidity [22].In the systemic review of Andarde et al., it was found that osteochondral mosaicplasty harvesting often leads to arthritic changes at the donor sites [23].However, within the same report, it was stated that no correlation was found between the number of and the size of the plugs and the donor site morbidity.None-theless, Andarde et al. also report that further studies should specifically report donor site morbidity due to a lack of information on donor site morbidity [23].
Thus, we may conclude that our study provides support for the use of mosaicplasty as a reconstructive technique, which could be used to provide good functional results and symptomatic relief.Surgeons should also be wary of possible complications from using the mosaicplasty technique.

CONCLUSION
Treatment of osteochondral lesions up to this day still presents a challenge [16,23,24].Once damaged, they will have little ability to regenerate and will stay damaged [16,22].
The present study has shown by virtue of histological examination, Lysholm score and VAS score that mosaicplasty could be successfully used to transplant the autografts and integrate them into traumatised cartilage and provide acceptable clinical results [21].Surgeons should be wary of possible donor site morbidity from the use of the mosaicplasty technique.

Fig. 1 .
Fig. 1.Open osteochondral autograft transfer (OAT) surgery through the medial para-patellar incision and debridement of the defect

Fig. 2 .
Fig. 2. Preparation and implantation of the osteochondral grafts.The right side photo shows the reconstructed defect with 4 grafts of 8 mm each.Further down, Fig. 5 will present arthroscopic findings after 6 months of the same patient.

Fig. 5 .
Fig. 5. Arthroscopic finding of successful integration of the osteochondral grafts

Table 2 .
List of additional operational procedures