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Patellofemoral Pain, Chondromalacia, Patellar Dislocation, Patellar-Tendon Disruption
See also Patellar Tendinopathy and Other Chronic Overuse Injuries of the Extensor Mechanism
For a brief overview of knee anatomy, physiology, and biomechanics, please click here.
For insight into the uselessness of X-rays in ascertaining mild articular-cartilage damage (e.g. as present in chondromalacia), please see the January 2006 article Radiographs Are Not Useful in Detecting Arthroscopically Confirmed Mild Chondral Damage, by Wright et al., in the Knee-Injury Diagnostics Subsection.
For insight into the worthlessness of thermal shrinkage in the context of dealing with articular-cartilage damage (including patellofemoral articular cartilage) defects, see the October 2005 article Monopolar Radiofrequency Treatment of Partial-Thickness Cartilage Defects in the Sheep Knee Joint Leads to Extended Cartilage Injury, by Kääb et al., in the Thermal Shrinkage and Other Faded Hopes Subsection.
The Effect of Bracing on Patellofemoral Joint Stress During Free and Fast Walking, Christopher M. Powers et al.; American Journal of Sports Medicine, Baltimore, Maryland, January 2004; Vol 32, pages 224-231. Comments: This study shows how patellar-tracking braces (essentially, neoprene sleeves with sewn-in felt sections designed to force the patella to track normally) affects patellofemoral stresses and gait during walking. (The patellofemoral brace studied was the DonJoy On-Track; however, the study findings would be expected to apply to all patellofemoral sleeve-type braces that use this same general design.) The authors had at their disposal a rather impressive collection of high-quality laboratory equipment: a 10-metre-long gait walkway with four force plates, six infrared cameras, and powerful motion-analysis software packages.
Neglected ruptures of the patellar tendon: A case series of four patients, Michael T. Casey et al.; American Journal of Sports Medicine, Baltimore, Maryland, Jul/Aug 2001; Vol 29/4, pages 457-460. Comments: Casey et al. describe a series of interesting cases of patellar-tendon failure, and how they repaired the damage by using multiple figure-8 loops of fine wire, thus avoiding the need for tissue-grafting.
The effects of patellar taping on patellofemoral incongruence: A computed tomography study, Antonio Gigante; The American Journal of Sports Medicine, Baltimore; Jan/Feb 2001, Vol 29/1, p. 88. Comments: This article delves into the biomechanical effects of various means of forcing the patella to track in its groove (i.e. usually forcing it to track more medially, hence medialization). He notes that merely forcing the patella sideways does not solve the root problems behind poor femoral-groove tracking, and cannot address improper angulation/tilt.
Patellofemoral Joint Complications and Considerations, Jenny McConnell; Knee Ligament Rehabilitation, edited by Todd S. Ellenbecker. Philadelphia, Pennsylvania: Churchill Livingstone (Harcourt), 2000. Pages 202-224. Comments: This superbly insightful article discusses in depth the complex biomechanics of the patella. The author notes how any loss of sensory nerve endings in knee tensile structures (such as the ligaments) and/or in other structures (including the highly pain-sensitive fat pads) can result in protracted problems. The author quotes research involving saline injections into knees (to simulate the blood released by ACL tearing), and notes how the vastus medialis becomes inhibited long before the vastus lateralis (and so it is not surprising that ACL-injury-history knees [including those which have undergone reconstruction] have patellar-tracking problems). The author goes on to discusses the importance of good strength in the innermost portion of the quadriceps (specifically the VMO, or vastus medialis oblique), and provides suitable training exercises in this regard. The author notes that a mere 5 millimetres of lateral displacement of the patella causes a 50 percent decrease in VMO tension. The author discusses the benefits of closed-kinetic-chain exercises (herein defined as exercises in which the foot is on the ground) in the context of patellar-tracking issues. (Closed-kinetic-chain exercises are also ideal for ACL rehabilitation.) These exercises are preferable because they improve patellar congruence, and also because with these types of exercises, muscle training is specific to limb position. Also noted is the importance of proper foot biomechanics. Too much or too little foot pronation will alter tibial rotation, which in turn affects patellofemoral joint mechanics. (Excessive foot pronation is often a result of a collapsed arch, and can result from various causes, including use of footwear containing inadequate arch support. The author additionally notes that although foot orthotics are often useful to correct such problems, the orthoses must not be too hard. Rigid orthoses can do more harm than good, because although they can support the arch, they can inhibit the natural movement of the foot which is essential to shock absorption.)
Immediate surgical repair of the medial patellar stabilizers for acute patellar dislocation: A review of eight cases, Christopher Ahmad; The American Journal of Sports Medicine, Baltimore; Nov/Dec 2000, Vol 28/6, p. 804. Comments: Ahmad et al. discuss a series of very successful surgical repairs of the injured medial patellar stabilizers (vastus medialis oblique muscle and medial patellofemoral ligament). (Note that "patellar dislocation" is very distinct from "knee dislocation". The latter entails catastrophic disruption of essentially all four major ligaments of the knee, and usually only results from high-kinetic-energy injuries such as from motor-vehicle accidents. Patellar dislocation, while painful, tends to occur independently of tibiofemoral-compartment major-ligament -- that is, ACL, PCL, MCL, LCL -- problems.)
Open- versus closed-kinetic-chain exercises for patellofemoral pain: A prospective, randomized study, Erik Witvrouw; The American Journal of Sports Medicine, Baltimore; Sep/Oct 2000, Vol 28/5, p. 687. Comments: This study evaluates the usefulness of open- versus closed-kinetic-chain exercises in the nonsurgical management of patellofemoral pain.
Characteristics of patients with primary acute lateral patellar dislocation and their recovery within the first six months of injury, David Atkin; The American Journal of Sports Medicine, Baltimore; Jul/Aug 2000, Vol 28/4, p. 472. Comments: This article looks at nonsurgical rehabilitation after patellar dislocation. The rehabilitation programme examined was a conservative one, and entailed range-of-motion exercises, muscle strengthening, gradual return to activity, and use of patellar-stabilizing braces (neoprene sleeves with patellar-tracking provisions).
Anteromedial tibial tubercle transfer in patients with chronic anterior knee pain and a subluxation-type patellar malalignment, Johan Bellemans et al.; American Journal of Sports Medicine, Baltimore; May/Jun 1997, Volume 25/5, p. 375-381. Comments: This article provides superb insight into the problem of chronic anterior knee pain generated by patellar problems. The article touches on the topics of knee alignment and osteotomies, in addition to patellar concerns. It also gives the Kujala scoring system (which Kujala originally presented in a 1993 AJARS article). Note that anterior knee pain can have causes other than patellar malalignment. For example, it is possible for the articular cartilage on the underside of the patella (and perhaps also in the femoral groove, also known as the trochlea) to have been damaged, thus resulting in chondromalacia (or patellofemoral pain). Although a maltracking patella can cause such cartilage damage, another possible cause is simply weak musculature (e.g. weak vastus medialis obliquus, the innermost portion of the quadriceps group).
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