Hot and cold knees: exploring differences in patella skin temperature in patients with patellofemoral pain.

OBJECTIVES: To investigate the distribution of patella skin temperature (Tsk) measurements and to explore the presence of temperature subgroups in patellofemoral pain (PFP) patients. DESIGN: Cross-sectional observational study design. PARTICIPANTS: One dataset of 58 healthy participants and 232 PFP patients from three different datasets. MAIN OUTCOME MEASURES: Patella skin temperature, measured by physiotherapists using a low cost hand held digital thermometer. The distribution of patella skin temperature was assessed and compared across datasets. To objectively determine the clinically meaningful number of subgroups, we used the average silhouette method. Finite mixture models were then used to examine the presence of PFP temperature subgroups. Receiver operating characteristic curves were used to estimate optimal patella Tsk thresholds for allocation of participants into the identified subgroups. RESULTS: In contrast to healthy participants, the patella skin temperature had an obvious bimodal distribution with wide dispersion present across all three PFP datasets. The fitted finite mixture model suggested three temperature subgroups (cold, normal and hot) that had been recommended by the average silhouette method with discrimination cut-off thresholds for subgroup membership based on receiver operating curve analysis of Cold=<30.0°C; Normal 30.0-35.2°C; Hot ≥35.2°C. CONCLUSION: A low cost hand held digital thermometer appears to be a useful clinical tool to identify three PFP temperature subgroups. Further research is recommended to deepen understanding of these clinical findings and to explore the implications to different treatments.

Double-Blind Randomized Controlled Trial: Injection of Autologous Blood in the Treatment of Chronic Patella Tendinopathy-A Pilot Study.

OBJECTIVE: To assess the efficacy of autologous blood injections (ABIs) against saline in patients with chronic recalcitrant patella tendinopathy (PT). DESIGN: Double-blind randomized controlled study. SETTING: Homerton Hospital Sports Medicine department. PATIENTS: Those with a diagnosis of refractory patellar tendinopathy were recruited between March 2010 and March 2012. INTERVENTIONS: Using 2 practitioners, patients were randomized to either receive ABIs or saline injections. MAIN OUTCOME MEASURES: All patients completed the Short-Form McGill Pain Questionnaire (MPQ), a visual analog scale (VAS), and a Victoria Institute of Sport Assessment for Patella Tendinopathy scale over a 12-month period. RESULTS: Twenty-two patients completed the final review at 12 months and were included in the study. Subjects ranged in age from 22 and 61 years and were randomized to 11 in each ABI and saline groups. Autologous blood injection group had a mean duration of symptoms of 16.7 months, whereas that of the saline group was 19.2 months. The saline group mean VAS score was reduced from 7.9 to 4.5 at 1 month (P = 0.003) and 3.3 (P = 0.005) at 1 year. With ABI, the score was reduced from 7.5 to 4.5 (P = 0.005) at 1 month and 3.1 (P = 0.003) at 1 year. Victoria Institute of Sport Assessment for Patella Tendinopathy, MPQ, and VAS scores improved significantly in both groups. CONCLUSIONS: This study demonstrated that both the ABI and saline groups experienced a significant improvement in symptoms. However, when the results were compared, there was no statistical difference between the 2 groups. CLINICAL RELEVANCE: This research showed that tendon fenestration is an alternative cost-effective treatment for recalcitrant PT.