Does early operative treatment improve outcomes of primary patellar dislocation? A systematic review

Patella alta and increased TT-TG distance do not adversely affect patient-reported outcomes following isolated MPFL reconstruction: A systematic review

OBJECTIVES

To analyze the effect of patellofemoral anatomical variations (patella alta, increased tibial tubercle-trochlear groove [TT-TG] distance, and trochlear dysplasia) on clinical outcomes after isolated medial patellofemoral ligament (MPFL) reconstruction.

METHODS

A comprehensive search from PubMed, Embase, and the Cochrane Library databases was conducted to identify studies that compared outcomes based on the presence or absence of patella alta, elevated tibial tubercle-trochlear groove (TT-TG) distance, and/or trochlear dysplasia. Exclusion criteria included reviews and meta-analyses, studies that included patients who underwent associated bony procedures, and those reporting outcomes after isolated MPFL reconstruction with no comparison between varying anatomical groups.

RESULTS

After application of selection criteria, 19 studies were included. Patella alta was not predictive of failure or poorer outcomes among 13 studies; however, 2 studies demonstrated poorer patient-reported outcome scores and/or higher failure rates with increasing patellar height. Increasing TT-TG distance demonstrated a statistically significant correlation with poorer outcomes in only one study, whereas 12 other studies showed no association. Trochlear dysplasia resulted in worse outcomes and greater failure rates in 6 studies, while 10 studies showed no statistically significant correlation between trochlear dysplasia and postoperative outcomes.

CONCLUSION

Patella alta and increased TT-TG distance did not adversely affect outcomes following isolated MPFL reconstruction in the preponderance of reviewed studies. Data are mixed regarding the impact of trochlear dysplasia on the outcomes of isolated MPFL reconstruction.

LEVEL OF EVIDENCE

IV.

Changes in Patellar Morphology Following Soft Tissue Surgical Correction of Recurrent Patellar Dislocation in Children with Low-Grade Trochlear Dysplasia

Objective

To investigate the changes in patellar morphology following soft tissue surgical correction of recurrent patellar dislocation in children with low‐grade trochlear dysplasia.

Methods

The prospective cohort study was performed between November 2007 and December 2012. Finally, 25 cases, with the mean age of 8.4 years (range from 7 to 10 years), were admitted to the study. All patients were diagnosed as bilateral recurrent patellar dislocation associated with femoral trochlear dysplasia. The knee that suffered injury or was dislocated was treated with medial patellar retinacular plasty (surgery group). The contralateral knee, which served as a control, was treated conservatively (conservative group). Axial CT scans were undertaken in all patients to assess the patellar morphological characteristics.

Results

The mean follow‐up time was 60.8 months (range 48 to 75 months). Preoperatively, there were no statistically significant differences between the patellar morphology in the two groups (P > 0.05). Many radiological parameters of patellar morphology were significantly different between the two groups at the final follow‐up, including well‐known parameters, such as the mean patellar width (surgery group, 40.58 mm [SD 1.26]; conservative group, 36.41 mm [SD 1.17]; P < 0.05), the mean patellar thickness (surgery group, 11.59 mm [SD 0.74]; conservative group, 9.38 mm [SD 0.56]; P < 0.05) and the mean Wiberg index (surgery group, 0.54 [SD 0.06]; conservative group, 0.72 [SD 0.08]; P < 0.05). There are also little‐known parameters, such as the ratio of length of lateral patella to medial patella (surgery group, 1.26 [SD 0.17]; conservative group, 1.69 [SD 0.21]; P < 0.05), which was a measurement of facet asymmetry. However, the Wiberg angle was not significantly different between the two groups (surgery group, 128.63° [SD 9.05]; conservative group, 125.47° [SD 13.96°]; P > 0.05) at the final follow‐up. No complications were found.

Conclusions

The patellar morphology can be significantly improved by early soft tissue surgical correction in children with patellar instability associated with low‐grade femoral trochlear dysplasia.

Changes in cartilage and subchondral bone in a growing rabbit experimental model of developmental trochlear dysplasia of the knee

Purpose: Trochlear dysplasia is one of the most frequent lower extremities deformities. Aim of this research was to investigate the changes in cartilage and subchondral bone of trochlea after patellar dislocation in growing rabbits. Materials and Methods: Ninety-six knees from 48 one-month-old rabbits were divided into two groups (experimental, control). Lateral patellar dislocation was established in the experimental group and distal femurs were collected at 4, 8, 12 and 24-week time points, respectively. General examination and histological observations were conducted to research the anatomical structure of the trochlear cartilage and subchondral bone. Structural parameters of trochlear subchondral bone were measured by MicroCT. Subsequently, the expression of TRPV4, collagen II and MMP-13 in cartilage were detected by western blot and RT-PCR analysis, respectively.Results: Subchondral bone loss was found in experimental group from 4 weeks after patellar dislocation, accompanied by increased TRAP-positive osteoclasts in subchondral bone. The trochlear dysplasia model was well established from 8 weeks after patellar dislocation. In addition, degeneration of cartilage was found from 8 weeks, accompanied by decreased expression of mechanically sensitive TRPV4 and collagen II, and increased expression of MMP-13.Conclusions: This study proved that trochlear dysplasia can be caused by patellar dislocation in growing rabbits, accompanied by significant subchondral bone loss. What is more, this study also shows that degenerative cartilage changes occur in the patellar dislocation model and become aggravated with time, accompanied by decreased TRPV4 and collagen II, but increased MMP-13.

Changes in femoral trochlear morphology following surgical correction of recurrent patellar dislocation associated with trochlear dysplasia in children

Aims

The aim of this study was to investigate the changes in femoral trochlear morphology following surgical correction of recurrent patellar dislocation associated with trochlear dysplasia in children.

Patients and Methods

A total of 23 patients with a mean age of 9.6 years (7 to 11) were included All had bilateral recurrent patellar dislocation associated with femoral trochlear dysplasia. The knee with traumatic dislocation at the time of presentation or that had dislocated most frequently was treated with medial patellar retinacular plasty (Group S). The contralateral knee served as a control and was treated conservatively (Group C). All patients were treated between October 2008 and August 2013. The mean follow-up was 48.7 months (43 to 56). Axial CT scans were undertaken in all patients to assess the trochlear morphological characteristics on a particular axial image which was established at the point with the greatest epicondylar width based on measurements preoperatively and at the final follow-up.

Results

Preoperatively, there were no statistically significant differences between the trochlear morphology in the two groups (sulcus angle, p 0.852; trochlear groove depth, p 0.885; lateral trochlear inclination, p 0.676; lateral-to-medial facet ratio, p 0.468; lateral condylar height, p 0.899; medial condylar height, p 0.816). Many radiological parameters of trochlear morphology were significantly different between the two groups at the final follow-up, including well-known parameters, such as the mean sulcus angle (Group S, 146.27° (sd 7.18); Group C, 160.61° (sd 9.29); p < 0.001), the mean trochlear groove depth (Group S, 6.25 mm (sd 0.41); Group C, 3.48 mm (sd 0.65); p < 0.001) and the mean lateral trochlear inclination (Group S, 20.99° (sd 3.87); Group C, 12.18° (sd 1.85); p < 0.001). Lesser known parameters such as the ratio of the lateral to medial trochlear length (Group S, 1.46 (sd 0.19); Group C, 2.14 (sd 0.42); p < 0.001), which is a measurement of facet asymmetry, and the lateral and medial condylar height were also significantly different between the two groups (p < 0.001).

Conclusion

The femoral trochlear morphology can be improved by early (before epiphyseal closure) surgical correction in children with recurrent patellar dislocation associated with femoral trochlear dysplasia. Cite this article: Bone Joint J 2018;100-B:811–21.

Primary patellar dislocations without surgical stabilization or recurrence: how well are these patients really doing?

PURPOSE

While a significant research has gone into identifying patients at highest risk of recurrence following primary patellar dislocation, there has been little work exploring the outcomes of patients who do not have a recurrent patellar dislocation. We hypothesize that patients without recurrent dislocation episodes will exhibit significantly higher KOOSs than those who suffer recurrent dislocations, but lower scores than published age-matched normative data.

METHODS

A retrospective review of patients with nonoperatively treated primary lateral patellar dislocations was carried out, and patients were contacted at a mean of 3.4 years (range 1.3-5.5 years) post-injury. Information regarding subsequent treatment and recurrent dislocations along with patient-reported outcome scores and activity level was collected.

RESULTS

One hundred and eleven patients (29.8 %) of 373 eligible patients agreed to study participation, seven of whom were excluded because they underwent subsequent patellar stabilization surgery on the index knee. Seventy-six patients (73.1 %) reported no further dislocation events, and the mean KOOS subscales at follow-up were: symptoms-80.2 ± 18.8, pain-81.8 ± 16.2, ADL-88.7 ± 15.9, sport/recreation-72.1 ± 24.4, and QOL-63.9 ± 23.8 at a mean follow-up of 3.3 years (range 1.3-5.5 years). No significant differences in any of the KOOS subscales were noted between these patients and the group that reported recurrent patellar dislocations. Only 26.4 % of the patients without further dislocations reported they were able to return to desired sport activities without limitations following their dislocation.

CONCLUSION

Patients who do not report recurrent patellar dislocations following nonoperative treatment of primary patellar dislocations are in many cases limited by this injury 3 years following the initial dislocation event.

LEVEL OF EVIDENCE

Retrospective cohort study, Level III.