IT is a case of mixed doubles for the injury-prone Pattens on the tennis courts of Government House. Hongkong's First Lady, Mrs Lavender Patten, is now hobbling around on crutches after pulling a muscle in her right leg while playing tennis on Thursday - on the same courts her husband, Chris, injured his right calf muscle in November. The injury is the latest in a string of mishaps which have befallen the Pattens since their arrival in Hongkong in July. The most serious ailment saw the Governor spend two days in hospital earlier this month to undergo a complicated procedure to widen two arteries in his heart. Under the steady gaze of geomancers fearful of bad fung shui at Government House, the family also endured teenage daughter Laura being struck down by an appendicitis days after their arrival. And, of course, there was the short but unhappy disappearance of family pooch Soda in November. Government information co-ordinator Mr Mike Hanson said last night Mrs Patten had not been troubled by the muscle before, but she had been checked by a doctor who believed it would heal quickly. ''It's not serious and she has still been able to continue with her normal duties - except for playing tennis,'' Mr Hanson said. The injury did not stop the Pattens dining with Lady Dunn last night at the Regent Hotel. After the meal, Mrs Patten was ferried in the official Daimler the 200 metres to the Tsim Sha Tsui waterfront to catch the Jose Carreras concert at the Cultural Centre. Restaurant staff said Mrs Patten managed to take her ''obvious discomfort'' in her stride, cheerfully chatting with staff. Regent general manager Mr Thomas Axmacher said he felt sorry for the Pattens' misfortune, saying: ''I know the Queen's got her Crown Jewels, but it looks as if they've got the Crown Crutches.'' The couple will spend the weekend at the Lodge at Fanling . . . fast becoming regarded as a convalescent home rather than a retreat from the vagaries of pressing business in Upper Albert Road.