Patients who undergo tibial tubercle anteromedialization with medial patellofemoral ligament reconstruction demonstrate similar rates of return to sport compared to isolated MPFL reconstruction

Reasons for and Complications Following Revision Tibial Tubercle Osteotomy

Background

While tibial tubercle osteotomy (TTO) is a highly effective treatment for patellofemoral malalignment, some patients may have recurrent symptoms after surgery. To date, there are little data on revision TTO (rTTO) and its outcomes.

Purpose

To evaluate the (1) reasons for and (2) complications following rTTO.

Study Design

Case series; Level of evidence, 4.

Methods

This was a retrospective review of patients who underwent rTTO from a single high-volume patellofemoral surgeon between 2016 and 2023. All included patients had a minimum of 3 months of follow-up data. Demographic characteristics, indications for primary and revision surgery, operative characteristics, concomitant procedures, range of motion at 6 and 12 weeks postoperatively, radiographic data, and complications were collected.

Results

There were 16 knees (14 patients) that underwent rTTO, including 10 (63%) for persistent malignment (all of which had chondral damage requiring concomitant intervention) and 6 (38%) for fracture/nonunion. The knees undergoing rTTO for malalignment were 90% female, compared with 33% female for fracture/nonunion (P = .04). For persistent malalignment rTTO, the only complication (10% [1/10]) was arthrofibrosis (0°-65° at 6 weeks postoperatively), requiring arthroscopic lysis of adhesions (0°-140° at 12 weeks postoperatively). Within the follow-up available (median, 2.2 years; range, 9 months-5.3 years), there were no cases of new or recurrent patellar instability after rTTO. Similarly, at a median follow-up of 1.2 years (range, 4 months-3.0 years), all 6 knees that underwent rTTO for fracture/nonunion achieved union, with delayed union requiring percutaneous bone marrow grafting at 4 months postoperatively being the only complication in this cohort.

Conclusion

Patients who underwent rTTO demonstrated low complication rates and high union rates in this study. There was a high prevalence of chondral damage requiring concomitant intervention among patients undergoing rTTO for persistent malalignment. While rTTO is a relatively rare procedure, these data suggest that it can be a safe and effective option for patients with recurrent symptoms or fracture/nonunion after primary TTO.

Recurrent patellar dislocation patients with high-grade J-sign have multiple structural bone abnormalities in the lower limbs

PURPOSE

To explore the relationship between preoperative J-sign grading and structural bone abnormalities in patients with recurrent patellar dislocation (RPD).

METHODS

A retrospective study was conducted on RPD patients over 5 years. Patients were categorised based on J-sign grade into low (J- and J1+), moderate (J2+) and high groups (J3+). Trochlear dysplasia (TD) and osseous structures (femoral anteversion angle [FAA], knee torsion, tibial tuberosity-trochlear groove [TT-TG] distance, Caton-Deschamps index) were assessed and grouped according to risk factor thresholds. The χ2 test was used to compare composition ratio differences of structural bone abnormalities among the groups.

RESULTS

A total of 256 patients were included, with 206 (80.5%) females. The distribution of J-sign grade was as follows: 89 knees (34.8%) of low grade, 86 moderate (33.6%) and 81 high (31.6%). Among the five structural bone abnormalities, TD was the most common with a prevalence of 78.5%, followed by increased TT-TG at 47.4%. Excessive tibiofemoral rotation had the lowest occurrence at 28.9%. There were 173 (67.6%) patients who had two or more abnormalities, while 45 (17.6%) had four to five bony abnormalities. Among patients with any bony abnormality, the proportion of high-grade J-sign surpassed 40%. Patients with moderate and high-grade J-sign had more increased FAA and more pronounced patella alta (all p < 0.001). The proportion of excessive knee torsion and TD increased with increasing each J-sign grade, with the more notable tendency in knee torsion (high vs. moderate vs. low-grade: 61% vs. 22% vs 7%, p < 0.001). Furthermore, the higher J-sign grade was also associated with more combined bony abnormalities (p < 0.001). In the high-grade J-sign group, 90.2% of the knees had two or more bony risk factors and 40.7% had four or more, which were significantly higher than the moderate and low-grade J-sign groups (40.7% vs. 11.6% vs. 2.2%, p < 0.001).

CONCLUSION

In patients with a high-grade J-sign, over 90% of the lower limbs had two or more structural bone risk factors, and more than 40% had four or more. These proportions were significantly higher compared to knees with low-grade and moderate J-sign. In clinical practice, when treating high-grade patellar mal-tracking, it is important to focus on and correct these strongly correlated abnormal bone structures.

LEVEL OF EVIDENCE

Level III.

Increased tibial tuberosity torsion has the greatest predictive value in patients with patellofemoral instability compared to other commonly assessed parameters

PURPOSE

The multifactorial nature of patellofemoral instability requires a comprehensive assessment of the affected patients. While an association between tibial tuberosity (TT) torsion and patellofemoral instability is known, its specific effect has not yet been investigated. This study investigated the effect of TT torsion on patellofemoral instability.

METHODS

This retrospective cohort study compared patients who underwent surgical intervention for patellofemoral instability and asymptomatic controls. TT torsion was measured in addition to other commonly assessed risk factors for patellofemoral instability using standardised computed tomography (CT) data of the lower extremities. The diagnostic performances of the assessed parameters were evaluated using receiver operating characteristic curve analysis and odds ratios (ORs) were calculated.

RESULTS

The patellofemoral instability group consisted of 79 knees, compared to 72 knees in the asymptomatic control group. Both groups differed significantly in all assessed parameters (p < 0.001), except for tibial torsion (n.s.). Among all parameters, TT torsion presented the best diagnostic performance for predicting patellar instability with an area under the curve of 0.95 (95% confidence interval [CI], 0.91-0.98; p < 0.001). A cut-off value of 17.7° yielded a 0.87 sensitivity and 0.89 specificity to predict patellar instability (OR, 55.2; 95% CI, 20.5-148.6; p < 0.001).

CONCLUSION

Among the evaluated risk factors, TT torsion had the highest predictive value for patellofemoral instability. Patients with TT torsions ≥ 17.7° showed a 55-fold increased probability of patellofemoral instability. Therefore, TT torsion should be included in the assessment of patients with patellofemoral instability.

LEVEL OF EVIDENCE

Level III.