Hypermobility is an acknowledged risk factor for patellar instability. In this case control study the influence of hypermobility on clinical outcome following medial patellofemoral ligament (MPFL) reconstruction for patellar instability was studied. A total of 25 patients with hypermobility as determined by the Beighton criteria were assessed and compared with a control group of 50 patients who were matched for age, gender, indication for surgery and degree of trochlear dysplasia. The patients with hypermobility had a Beighton Score of ≥ 6; the control patients had a score of < 4. All patients underwent MPFL reconstruction performed using semitendinosus autograft and a standardised arthroscopically controlled technique. The mean age of the patients was 25 years (17 to 49) and the mean follow-up was 15 months (6 to 30). Patients with hypermobility had a significant improvement in function following surgery, with reasonable rates of satisfaction, perceived improvement, willingness to repeat and likelihood of recommendation. Functional improvements were significantly less than in control patients (p < 0.01). Joint hypermobility is not a contraindication to MPFL reconstruction although caution is recommended in managing the expectations of patients with hypermobility before consideration of surgery

Aims

The aim of this study was to determine and compare the congruency of the articular surface contact area of the patellofemoral joint (PFJ) during both active and passive movement of the knee with the use of an MRI mapping technique in both the stable and unstable PFJ.

Patellar instability most frequently presents during adolescence. Congenital and infantile dislocation of the patella is a distinct entity from adolescent instability and measurable abnormalities may be present at birth. In the normal patellofemoral joint an increase in quadriceps angle and patellar height are matched by an increase in trochlear depth as the joint matures. Adolescent instability may herald a lifelong condition leading to chronic disability and arthritis.

Restoring normal anatomy by trochleoplasty, tibial tubercle transfer or medial patellofemoral ligament (MPFL) reconstruction in the young adult prevents further instability. Although these techniques are proven in the young adult, they may cause growth arrest and deformity where the physis is open. A vigorous non-operative strategy may permit delay of surgery until growth is complete. Where non-operative treatment has failed a modified MPFL reconstruction may be performed to maintain stability until physeal closure permits anatomical reconstruction. If significant growth remains an extraosseous reconstruction of the MPFL may impart the lowest risk to the physis. If minor growth remains image intensifier guided placement of femoral intraosseous fixation may impart a small, but acceptable, risk to the physis.

This paper presents and discusses the literature relating to adolescent instability and provides a framework for management of these patients.

Cite this article: Bone Joint J 2017;99-B:159–70.

We report a prospective analysis of clinical outcome in patients treated with medial patellofemoral ligament (MPFL) reconstruction using an autologous semitendinosus graft. The technique includes superolateral portal arthroscopic assessment before and after graft placement to ensure correct graft tension and patellar tracking before fixation. Between October 2005 and October 2010, a total of 201 consecutive patients underwent 219 procedures. Follow-up is presented for 211 procedures in 193 patients with a mean age of 26 years (16 to 49), and mean follow-up of 16 months (6 to 42). Indications were atraumatic recurrent patellar dislocation in 141 patients, traumatic recurrent dislocation in 50, pain with subluxation in 14 and a single dislocation with persistent instability in six. There have been no recurrent dislocations/subluxations. There was a statistically significant improvement between available pre- and post-operative outcome scores for 193 patients (all p < 0.001). Female patients with a history of atraumatic recurrent dislocation and all patients with history of previous surgery had a significantly worse outcome (all p < 0.05). The indication for surgery, degree of dysplasia, associated patella alta, time from primary dislocation to surgery and evidence of associated cartilage damage at operation did not result in any significant difference in outcome.

This series adds considerably to existing evidence that MPFL reconstruction is an effective surgical procedure for selected patients with patellofemoral instability.

We assessed hyperextension of the knee and joint laxity in 169 consecutive patients who underwent an anterior cruciate ligament reconstruction between 2000 and 2002 and correlated this with a selected number of age- and gender-matched controls. In addition, the mechanism of injury in the majority of patients was documented. Joint laxity was present in 42.6% (72 of 169) of the patients and hyperextension of the knee in 78.7% (133 of 169). All patients with joint laxity had hyperextension of their knee. In the control group only 21.5% (14 of 65) had joint laxity and 37% (24 of 65) had hyperextension of the knee. Statistical analysis showed a significant correlation for these associations. We conclude that anterior cruciate ligament injury is more common in those with joint laxity and particularly so for those with hyperextension of the knee.

We present the ten- to 15-year follow-up of 31 patients (34 knees), who underwent an Elmslie-Trillat tibial tubercle osteotomy for chronic, severe patellar instability, unresponsive to non-operative treatment. The mean age of the patients at the time of surgery was 31 years (18 to 46) and they were reviewed post-operatively, at four years (2 to 8) and then at 12 years (10 to 15). All patients had pre-operative knee radiographs and Cox and Insall knee scores. Superolateral portal arthroscopy was performed per-operatively to document chondral damage and after the osteotomy to assess the stability of the patellofemoral joint. A total of 28 knees (82%) had a varying degree of damage to the articular surface. At final follow-up 25 patients (28 knees) were available for review and underwent clinical examination, radiographs of the knee, and Cox and Insall scoring. Six patients who had no arthroscopic chondral abnormality showed no or only early signs of osteoarthritis on final radiographs; while 12 patients with lower grade chondral damage (grade 1 to 2) showed early to moderate signs of osteoarthritis and six out of ten knees with higher grade chondral damage (grade 3 to 4) showed marked evidence of osteoarthritis; four of these had undergone a knee replacement. In the 22 patients (24 knees) with complete follow-up, 19 knees (79.2%) were reported to have a good or excellent outcome at four years, while 15 knees (62.5%) were reported to have the same at long-term follow-up. The functional and radiological results show that the extent of pre-operatively sustained chondral damage is directly related to the subsequent development of patellofemoral osteoarthritis.

Cite this article: Bone Joint J 2013;95-B:478–85.