The following electronic only articles are published in conjunction with this issue of BJSM (see also pages 253 and 297)

High strain mechanical loading rapidly induces tendon apoptosis: an ex vivo rat tibialis anterior model

A Scott, K M Khan, J Heer, et al

Background: The role of apoptosis, or programmed cell death, has only recently been explored in tendon.

Objective: To investigate the development of apoptosis after high strain loading of rat tendon.

Methods: The right tibialis anterior tendons of three rats were prepared for mechanical loading, and left tendons were prepared identically as non-loaded controls. Tendon was loaded with 20% strain for six hours using a 1 Hz longitudinal sine wave signal. The following were used to assess apoptosis: (a) a monoclonal mouse antibody (F7-26) to label single stranded DNA breaks; (b) a rabbit polyclonal antibody that specifically recognises the cleaved form of caspase-3.

Results: Light microscopy confirmed that the high strain protocol induced a stretch overload injury. Control tendons showed little or no staining with the F7-26 antibody, but the loaded tendons displayed numerous apoptotic cells. The percentage of apoptotic cells (20%) in the loaded tendon was significantly greater than in the control tendon (1%) (p  =  0.000). The labelled cells colocalised with abnormal nuclear morphology, including nuclear fragmentation. The staining against cleaved caspase-3 was positive in loaded tendons only, and localised both to nucleus and cytoplasm.

Conclusion: This experiment extends knowledge of human tendon apoptosis by showing that apoptosis can occur in response to short term, high strain mechanical loading. This is the first report of mechanical loading of intact tendon causing excessive apoptosis (221 w).

(Br J Sports Med 2005;39:e25) http://bjsm.bmjjournals.com/cgi/content/full/39/5/e25

The kick with the kite: an analysis of kite surfing related off shore rescue missions in Cape Town, South Africa

A K Exadaktylos, G M Sclabas, I Blake, et al

Background: This study analyses kite surfing related off shore rescue missions in Cape Town, South Africa with the aim of providing more information on the frequency, pattern, and severity of kite surfing related injuries.

Methods: The observation period for this study started on October 1, 2003 and ended on May 1, 2004 and included 30 air rescue missions. Data and information were collected prospectively.

Results: The Air Mercy Service in Cape Town Province responded to 30 requests for help. Twenty five accidents were attributed to inability to detach the kite from the harness. Injuries occurred in five incidents and included fractures of the upper arm, ribs and ankle, and lacerations and contusions to the head and neck. Two patients suffered from hypothermia and one experienced severe exhaustion. All surfers were rescued successfully and there were no fatal accidents.

Discussion: The risk potential of this new sport is unclear. Dangerous situations can occur despite proper training and safety precautions due to unpredictable conditions and difficulties with equipment. Safety should be stressed. Surfers should sailing with a fellow kiter and should wear a life vest. More efforts must be taken to make this booming new water sport safer.

(Br J Sports Med 2005;39:e26) http://bjsm.bmjjournals.com/cgi/content/full/39/5/e26