The most common recurrent symptom reported by people is patella or knee cap instability. It may be associated with abnormal shape of the knee joint bones, weakness of the muscles around the hip or knees or tightness of soft tissues on the outside of the knee.
When the patella dislocates, injury to the soft tissues of the knee joint occurs, which requires a period of rehabilitation. This may include treatments such as immobilisation and bracing (to limit knee movement), exercises, manual therapy, taping and electrotherapy modalities such as therapeutic ultrasound or electrical stimulation. However, some surgeons have suggested that people may have a better outcome if surgery is performed to repair or reconstruct the injured ligaments and muscles, re-shape the lower femur or change the position of where the patella attaches to the shinbone (tibia) to restrain the kneecap from dislocating again.
Results of the search and description of studies
This is an update of a previous Cochrane review. We searched the medical literature until October 2014 and we found six relevant studies (344 participants) that looked at the results of surgery compared with non-surgical treatment for people who had a kneecap dislocation. The studies allocated people to a surgical or non-surgical treatment group randomly. All study participants were being treated for a first-time dislocation. The mean ages in the individual studies ranged from 19 to 26 years, with four studies including children, mainly adolescents, as well as adults. Follow-up for study participants in the six included studies ranged from two to nine years.
Key results
The review found evidence of lower risk of repeated knee cap dislocation for those who underwent surgery compared with non-surgical intervention following first-time dislocation at two to five years follow-up. There was weaker evidence of a lower risk at six to nine years follow-up and an increased risk after surgery could not be ruled out. Very limited evidence for patient-rated knee and physical function outcome measures did not show a difference between the two groups. Although, evidence for an outcome measure that was specific to kneecap disorders was in favour of surgery at two to five years follow-up, the evidence at six to nine years follow-up did not show a benefit of surgery and tended to favour non-surgical treatment. One study only reported on adverse effects of treatment. This reported four major complications after surgery. Although slightly more people in the surgery group had subsequent surgery at six to nine years, the evidence for this outcome was inconclusive.
Quality of the evidence
These studies were small and had some weaknesses in their design and conduct. Overall, the quality of the evidence is very low and thus we were very uncertain about these findings.
Conclusions
Our review concludes that the evidence is not of sufficient quality to confirm a significant difference in outcome between surgical or non-surgical initial management of people who have dislocated their kneecap for the first time. There were no studies of people with recurrent patellar dislocation. Good quality research studies that are based on expert consensus about the condition and interventions and that involve a large number of people are required.
Authors' conclusions:
Although there is some
evidence to support surgical over non-surgical management of primary
patellar dislocation in the short term, the quality of this evidence is
very low because of the high risk of bias
and the imprecision in the effect estimates. We are therefore very
uncertain about the estimate of effect. No trials examined people with
recurrent patellar dislocation. Adequately powered, multi-centre,
randomised controlled trials, conducted and reported to contemporary
standards, are needed. To inform the design and conduct of these trials,
expert consensus should be achieved on the minimal description of both
surgical and non-surgical interventions, and the anatomical or
pathological variations that may be relevant to both choice of these
interventions and the natural history of patellar instability.
Furthermore, well-designed studies recording adverse events and
long-term outcomes are needed.