Our results indicate that the therapy proved effective. Lysholm and Kujala Scores improved significantly, and only two patients (7.7%) suffered from redislocation, with no need to reoperate; both patients were performing highly-demanding activities. This recurrence rate is very similar to that reported in literature, which ranges from 1.2 to 13 percent [10,12,14,16,26-30]. Most previous works indicate improvement within the scope of functional scale. However, the populations included in these studies usually vary considerably with regard to age and implemented MPFL reconstruction methods, particularly concerning the use of TTO, and very few are based on groups with homogeneous age and maturation advancement. It is well known that the prior to adolescence, children demonstrate a much higher redislocation rate than adults. We believe that combining these groups does not provide a suitably homogeneous population to analyse the applied operating methods and preoperative qualification. In our cases, the treatment results were also confirmed by radiological indices: a significant improvement in two main indicators, namely CA and PFA, was observed in patients who did not have the TTO and lateral release performed. Interestingly, our findings indicate a significant correlation between the Kujala Score and the CA, which confirms the substantial impact this index has on treating RPD.
In our study, we elaborated our own qualification to undergo lateral release; it was performed only in patients with PFA of more than 10 degrees, diagnosing a severe tilt. It is important to note that our results indicate a statistically significant correlation between PFA and both the Kujala and Lysholm scores; there is hence a need for a more detailed examination of the value of PFA, and it should be considered when planning surgery, especially in the case of unsatisfactory results or in patellofemoral pain cases. Malatray et al. report no indication for systemic lateral release in a population of 33 patients (18-45 years old) with MPFL reconstruction; no differences in International Knee Documentation Committee (IKDC) score or patellar tilt were found between those who underwent lateral release during MPFL and those who did not during a one - year follow-up .
Another parameter that has been analysed in literature is the influence of MPFL reconstruction on patellar height, expressed with the CDI index. Although patellar height in our cases was not corrected, the administered treatment proved successful, both with regard to the recurrence, and to the result of the subjective survey evaluation during the three-year follow-up. Nevertheless, a study by Luceri et al. found the patellar height decreasing in a group of 95 knees in mature patients after isolated MPFL reconstruction, mean age 25 years . Similarly, Lykissas et al. report a significant decrease of patellar height indices after MPFL reconstruction in 38 patients, mean age 14.2 years, during a six month follow-up, as indicated by X-ray analysis .
The most controversial subject, and one that has been widely described in literature, is the mean of the femoral insertion positioning. In our practice, we use anatomical landmarks [18,19]. In the present study, none of the procedures used fluoroscopy guidance according to Schöttle; instead, graft isometry was employed, regardless of the femoral positioning. Despite this, McCarthy et al. propose that using non-anatomical points is associated with a worse result, and emphasise that graft tension is a more important factor . However, an analysis of 27 cases of MPFL reconstruction including different femoral insertion placements by Larson et al. did not confirm worse outcomes in those with non-anatomical placement of femoral tunnel after a one-year follow-up . Interestingly, in a study of 64 patients with a median age of 24 years old, Koenen et al. found that fluoroscopy enabled more accurate femoral tunnel positioning; however, this particular study did not include any comparison with the results obtained by other positioning methods .
Campos et al. emphasise that as far as trochlear dysplasia is concerned, the Schöttle’s point is not suitable for a femoral tunnel; their study based on 40 cases indicates that it is better to use a more proximal point in this group of patients, and that taking this approach should improve accuracy in pre-op planning .
The qualification to TTO is another extremely interesting and very controversial issue. As mentioned above, some papers propose that distal realignment is unnecessary, as MPFL reconstruction alone can yield good results. A review of 27 knees by Pesenti et al. in children (mean age 13.8 years) treated with isolated MPFL reconstruction, regardless of anatomical osseous abnormalities, identified one recurrence (3.8%), with a mean Kujala score of 95.5 points during 41 months of follow-up . In another study of 211 isolated MPFL reconstructions with an mean age of 20.6 years, Sappey-Marinier et al. report a significant increase in the Kujala score over a 5.8-year follow-up; in addition, 4.7% recurrences required revision. No TTO was performed in any patient, even those with the increased TT-TG, patella alta and J-sign before surgery . Similarly Mulliez et al. indicate no difference between patients who had TTO and those who did not, in a study of 129 knees with a minimum one-year follow-up . These findings are confirmed by those of Erickson et al., regarding 90 patients with a mean age of 19 years who underwent RPD treatment: the findings indicate a good result over a two-year follow-up, regardless of anatomical factors such as the increased TT-TG, CDI or Dejour index .
In our present study, although we decided to strengthen the criteria concerning the TTO, we continued to take certain anatomical factors into consideration, i.e. TT-TG exceeding 20 mm and lateralisation of the patella in 45 degrees Merchant view expressed in CA of more than five degrees. Based on our past and present studies, we recommend this methodology in daily practice.
When compared with the available literature, the greatest limitation of our paper is the relatively small size of the study group. Our attempts to ensure a homogenous population unfortunately came at the expense of its size, and some subjects were inevitably lost during the follow-up. However, the study group we were able to create was of sufficient size to allow standardised statistical analysis. Additionally, our group size is equivalent or even larger than many used in previous studies [10-12,16,31]. Another disadvantage of our publication might be associated with the follow-up period, which should be longer to assess the real long-term results; nevertheless, a three-year follow-up seems to be longer than most used previously [10-13,16,31,33].