© Springer International Publishing Switzerland 2016
Piero Volpi (ed.)Arthroscopy and Sport Injuries10.1007/978-3-319-14815-1_1111. Patellar and Quadriceps Tendinopathy
(1)
Orthopaedic and Traumatology Department, Faculty of Medicine, “Kirk Kilgour” Sports Traumatology Center, S. Andrea Hospital, University “La Sapienza”, Grottarossa St. 1037, Rome, 00189, Italy
(2)
Sports Traumatology Center, S. Andrea Hospital, University of Rome “La Sapienza”, Via Grottarossa 1035, Rome, 00100, Italy
Keywords
Quadriceps tendinopathyPatellar tendinopathyInsertional tendinopathyJumper’s kneeCatastrophic jumper’s knee11.1 Introduction
Quadriceps and patellar tendinopathies are known as “jumper’s knee,” similarly following a tradition of reference to the etiology of a pathology, such as “tennis elbow” or “thrower’s shoulder.”
Even though patellar tendinopathy had already been described in Italy [1], the term “jumper’s knee” was due to a study published in 1973 by Blazina et al. [2], one of the coworkers of the famous sports physician Frank Jobe, Chief of the Sports Medicine Center in Inglewood (California, USA), located near the sports center where the prestigious Los Angeles Lakers team now plays. It was certainly to the basketball players that Blazina was referring when he wisely described the painful syndrome “jumper’s knee.”
Successively, many other studies have focused on this so far unclear pathology which deserves to be known by sports physicians who, considering the frequency of this pathology in some types of players, will have to face this pathology during their career.
In this chapter, we will discuss the different aspects of patellar and quadriceps pathologies according to the most recent experiences and the newest types of treatments.
11.2 Epidemiology and Predisposing Factors
As cited above, patellar and quadriceps tendinopathies are very common among athletes involved in jumping activities or whose activity is based on the use of the lower limb’s extensor apparatus (such as weight lifters). It has been estimated that up to 40 % of volleyball players suffer or have suffered from this pathology during their career [3].
In the sport of soccer, jumper’s knee syndrome was unknown until the 1980s, when coaches started putting more attention on basic training with weight-lifting exercises, jumping (plyometric), eccentric strengthening, and so forth. Nowadays patellar tendinopathy affects about 2.5 % of soccer athletes, data which is still lower compared to athletes of other sports who comprise the highest percentage of incidence (volleyball, basketball) [4, 5].
Predisposing factors to the onset of such a pathology are classified as “intrinsic” and “extrinsic”; intrinsic factors mean those related to the athlete, and extrinsic are those due to environmental stresses.
Besides sex incidence, which is higher in male patients, many epidemiologic studies have shown no correlation between morphologic characteristics of patients and jumper’s knee syndrome. In particular, it has never been shown that varus or valgus malalignment of the knee, a malalignment of the extensor apparatus, a patellar hypermobility, or a high or low patella syndrome might be predisposing factors, and aside from the knee area, nor have valgus hindfoot deformity, pronated foot valgus, cavus foot, or even others. Researchers’ interest therefore focused more on peculiar characteristics of the patellar tendon tissue and on its collagen composition.
However, the results about extrinsic factors were different. The first data, which is also the most obvious, concerns the correlation between the number of training sessions and matches per week and the incidence of jumper’s knee syndrome. This strict positive correlation clearly confirms the importance of overuse in the onset of such a type of tendinopathy. Conversely less significant was the type of training (if carried out with weights, therabands, or jumps) [6].
Training fields have been widely studied with the result that the harder the field, the higher the incidence. Regarding soccer games however, there do not seem to be significant differences between players who usually train on natural fields and those who train on artificial fields [7].
Other factors predisposing patellar tendinopathy, which might be considered both intrinsic and extrinsic, regard jumping capability with a higher incidence among athletes with higher explosive strength [8].
11.3 Symptomatology and Classification
The main symptom of jumper’s knee is pain, with varying intensity, but always, localized in one of the typical places which represent the fulcrum of the extensor apparatus. The most frequent localization is the origin of the patellar tendon at the lower site of the patella (70 % of the cases), followed by the insertion of the quadriceps tendon at the superior site of the patella (20 %) and by the insertion of the patellar tendon on the anterior tibial tuberosity (10 %). The most recent classifications are based on the intensity of the pain with jumper’s knee which, compared to the first classification proposed by Blazina, focus more attention on evaluating the effect of the pain on sports performance.
11.3.1 Jumper’s Knee Classification According to Symptoms
Ferretti and coworkers [9]
STADIUM 0 – No pain
STADIUM I – Rare pain with no sports restriction
STADIUM II – Moderate pain during sports activity with no restriction on sports performance (normal performance)
STADIUM III – Pain with slight qualitative and quantitative restriction on performance (reduced number of training sessions or minor intensity)
STADIUM IV – Pain with severe restriction of sports performance
STADIUM V – Pain during daily activity; sports activity impossible
As we can see, the classification above described does not take into account rupture of the patellar tendon (catastrophic jumper’s knee) [10] which cannot be considered the evolution of the insertional patellar tendinopathy but an acute event as a consequence of a chronic tendinous degeneration, which is totally different from an anatomo-pathology point of view. Indeed the discrepancy between pain (severe) and tendinous damage (moderate) seen in jumper’s knee forces the athlete to suspend the activity much earlier before the pathology leads to rupture; the exact opposite happens with tendinosic degeneration where the tendinous damage is severe and progressive with a painful symptomatology usually moderate or even absent. By an objective point of view, local digital pain represents the only important factor. Locally, in some cases, we can observe a mild swelling of the soft tissue but never an articular effusion. Knee articular semeiotic, as well as the one concerning the extensor apparatus, is negative.
11.4 Radiological Findings
Radiological evaluation consists of X-rays, ultrasound evaluations, and magnetic resonance imaging. Standard X-rays might show insertional calcifications (spurs) which show the exact localization of the pathology. Ultrasound may show a thickening of the patellar tendon close to the insertion and even a loss of the normal fibrillar pattern. Recently ultrasound has also been used to study patellar tendon vascularization (eco color Doppler): this methodology might show cases with hypervascularization as well as cases of normal or reduced vascularization, even though these patterns are not adequately understood [11]. Magnetic resonance allows better definition of the tendon morphology which often shows a tendon modification at the insertional site. However, MRI rarely ever changes therapeutic protocol.
11.5 Anatomo-pathology
With regard to anatomo-pathologic classification of overuse tendinopathy as proposed by Perugia et al. [12], jumper’s knee might be included in the insertional tendinopathies.
On the other hand, an anatomo-pathologic pattern of subcutaneous ruptures usually represents the consequence of a chronic degenerative process (tendinosis) which is often totally asymptomatic and which usually occurs, abruptly, with an acute rupture. In these cases tendinous tissue shows wide areas of degeneration with lack of the normal fibrillar pattern and an important reduction in the cellular component.
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