IntroductionThetibial tuberosity to trochlear groove (TTTG) is a well-known orthopaedicradiographic measurement around the knee joint. This measurement in the westernpopulation is a well-recognized entity and widely studied through variousmodalities such as X-rays, computerized tomography (CT) and magnetic resonanceimaging (MRI) 1-3.
However no literature iscurrently present to indicate that the TTTG distance has been studied in theBlack African population.Thismeasurement is of clinical significance due to its relevance in patellainstability4. It plays a pivotal role when deciding on the need forsurgery.
Wecurrently know that the normal TTTG measurement is less than 15mm. Theliterature also suggests that anything above 20mm needs to be considered for abony surgical procedure (e.g. medializing osteotomy of tibial tuberosity) 5-7.Thepurpose of this comparative study was to measure the TTTG measurement in theBlack African population and compare it to the Western quoted norms in theliterature.
Thisstudy does not aim to assess patella instability as a pathology but ratherscrutinize the measurement in isolation. CurrentKnowledgeTheTTTG measurement was first described by Goutallier and Bernageau in 1978 8 based on x-raymeasurements.Dejouret al then adapted the same measurement to the CT scan in 1987 9. His set of patients with patella instability and hiscontrol group were derived from the French population. His control group had anaverage measurement of 12.7mm +-3.4mm and showed that a measurement of >20mmwas present in pathological cases.
Alemparteet al, in a Level 1 study, reported that a large variation may even be presentin asymptomatic patients10. This study found normalTTTG values of 13.6 +- 8.8mm.KimT.K.
et al reported in a systematic review about the morphological differencesthat exist in certain anatomical features and measurements around the knee11. Tse et al suggested thatactually the threshold for tibial tuberosity transfer shouldrather be lower in Chinese patients12. Koerner et al has also queried the variations of “normal”femoral versions amongst genders and ethnicities13. This in turn bringsabout the discussion of a range of possible ethnic differences when it comes toanatomical structure and previously believed to be normal TTTG measurements.