Patellar Instability (West and Colvin) - The Patellofemoral Foundation

NUMBERD2758dTHE J OURNAL OF B ONE &JOINT S URGERY JBJS. ORGd dVOLUME 90-A 12 ECEMBER 2008PATELLAR I NSTABILITYFig. 5Tibial tubercle realignment. A: A flat (no-angle) osteotomy allows medialization of the tibial tubercle. The elevator protects theneurovascular bundle. B: A steeper cut for equal anteriorization and medialization of the tibial tubercle. C: A very steep cut providesmaximum anteriorization of the tibial tubercle with less medialization. (Reprinted, with permission, from: Buuck DA, Fulkerson JP.Anteromedialization of the tibial tubercle: a 4- to 12-year follow-up. Op Tech Sports Med. 2000;8:136-7.)Carney et al. reviewed the results of the Elmslie-Trillatprocedure for the treatment of recurrent subluxation anddislocation of the patella in fifteen knees in fourteen patients 89 .The authors compared the outcomes at a mean of three yearswith those at a mean of twenty-six years and found no differencein instability between the two time-periods. Althoughnot significant, there was a trend toward a worsening Coxscore 90 with time, which occurred even though the articularcartilage was grossly intact.Koeter et al. reported the results of medial realignment ofthe tibial tubercle for patients with either painful lateral maltracking(with no instability) or patellar instability for longerthan one year and a tibial tubercle-trochlear groove distanceof >15 mm 86 . There was no difference in the distance of themedial displacement between the groups. A mean of 5.7 mm ofdistalization of the tibial tubercle was achieved in nine patientswith lateral maltracking and twenty-two patients with patellarinstability. At two years postoperatively, although the patientswith patellar instability had more variable outcomes, bothgroups had improvement in all scores, with no significantdifference noted between the groups. Thus, the authors advocateda medial transfer, with or without distalization, for patientswith either patellar maltracking or patellar instability.Diks et al. found that a tibial tubercle transfer providedbetter results for patients with patellar maltracking and no instabilitythan for patients with isolated patellar instability 83 .Tibialtubercle transfer was performed in forty-three knees, twentysevenwith objective evidence of patellar instability and sixteenwith a laterally tracking patella. The mean duration of follow-upwas thirty-seven months. The transfers in the patients with patellarinstability were, overall, more effective in improving stability,doing so in 96% (twenty-six) of the twenty-seven patients,than they were in improving pain (63% of the patients). Onthe other hand, a higher percentage of patients (81%, thirteenof sixteen) with patellar maltracking had good pain relief.Barber and McGarry advocated the use of the modifiedElmslie-Trillat procedure for treatment of patellofemoral instabilitywithout evidence of arthritis 87 .Theseauthorsperformeda medial translation of the tibial tubercle hinged on adistal periosteal flap along with an arthroscopic lateral retinacularrelease and medial capsular reefing for patients with atleast three recurrent patellar dislocations or subluxations thathad been resistant to a minimum of three months of physicaltherapy or bracing. Of thirty-five patients followed for a meanof ninety-eight months, 91% (thirty-two) had no additionalsubluxations or dislocations. Furthermore, there was improvementin the IKDC 65 ,Fulkersonknee 79 , and Lysholm andGillquist 77 scores.Fulkerson et al. described anteromedialization of the tibialtubercle to address degenerative changes of the articular cartilage79 (Fig. 5). In a cadaver model of this procedure, pressure wasshown to be decreased on the lateral patellar facet at lowerangles of flexion (up to 30°) whereas pressure was equalizedbetween the medial and lateral patellar facets at greater angles offlexion 85 . There was slight superior migration of the contact areaof the patellofemoral joint with distalization 85 . Cadaver studieshave also demonstrated that anteromedialization decreases thecontact pressures on the trochlear side overall, primarily on the