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CLASSIFICATION OF PFPS

into a specific category of PFPS and con- sequently provide him/her with the most appropriate rehabilitation.

This article will use a classification of PFPS in different entities, based on a clin- ical assessment. The treatment pro- gramme is then based on the unique pre- sentation of the patient and the use of this classification system.

CLINICAL CLASSIFICATION - ASSESSMENT OF PFPS At the end of the assessment of the PFPS patient we need to: a) know what the condition of the muscu- lar structures around the knee are b) require a good idea of the alignment - or present malalignment - of the patellofemoral joint and whole lower extremity.

At first we focus on the muscular struc- tures.

MUSCULAR ASSESSMENT An evaluation of the muscular structures is not synonymous with a strength examina- tion, as it involves more than that. A mus- cular assessment in PFPS patients needs to focus on muscular strength, neuromuscular coordination, and muscle flexibility.

Muscular strength Quadriceps assessment At first many PFPS patients present with an atrophy of the quadriceps as a whole. In many cases this hypotrophy results specifically in strength loss (frequently associated with the presence of pain) dur- ing eccentric quadriceps contractions (descending stairs). Consequently, a strength evaluation seems important in PFPS. This strength evaluation can best be performed by an isokinetic measurement. Strength deficits of 15% or more are con- sidered abnormal and should be treated. Since an isokinetic measurement is not always on hand for therapists, a function- al strength evaluation by means of a func- tional hop test combined with a thigh hypotrophy measurement can also be used to identify a possible strength loss. The one legged hop test is performed by jump- ing and landing on the same foot with the hands behind the back. A quotient (%) between the injured and non-injured leg is registered and is defined as abnormal if the quotient is less than 85%. In addi- tion, the measurement of the thigh

Biceps femoris

Illiotibial tract

Vastus lateralis

Lateral patellar retinaculum

Sartorius Gracilis

Rectus femoris

Vastus medialis

Cojoined ten- don of semi- tendonosus, gracilis and sartorius

Patella

Lateral collateral ligament

hypotrophy is also easy to perform, and correlates well with deficits in isokinetic knee extensor torque. Therefore when an isokinetic measurement is not available thigh hypotrophy measurements should be combined with the one legged hop test.

Quadriceps strengthening If loss of quadriceps strength is observed, strengthening exercises should be given. The question then arises regarding which kind of exercises (open versus closed kinetic chain) should be used for PFPS.

Generally it has been suggested that closed kinetic chain exercises are safer than open kinetic chain exercises because the former place minimal stress on the patellofemoral joint in the functional range of motion (4,5). Therefore patellofemoral pain syndrome patients may tolerate closed kinetic chain (CKC) exercises better, and consequently exhibit better functional results after a CKC reha- bilitation programme. However clinical studies show that both open and closed kinetic chain exercise programmes lead to an improved subjective and clinical out- come in patients with PFPS (6,7).

The best functional results for some of the tested parameters in the closed kinetic chain group suggest that a combination of both training modalities (OKC and CKC) should be used in conservative treatment of patients with PFPS (6,7). The use of CKC versus OKC exercises depends greatly on the range of motion (ROM) in which the

Figure 2: Muscles on the medial aspect of the knee

therapist wants to train. When considering the ROM it is vital to note that during CKC exercises patellofemoral stress steadily increases as the knee is moved from termi- nal extension to a flexed position. The opposite happens during OKC exercises, since the PF stress increases as the knee is moved from a flexed position to full exten- sion (figure 1). Therefore, it can be con- cluded that CKC exercises are preferably performed between terminal extension and 50° of knee flexion and OKC exercises between 90° and 50° of knee flexion. This way, the patient can train during the whole ROM, while keeping the patellofemoral stress low. Once the patient’s patellofemoral joint is able to withstand more stress (no pain during CKC exercises), CKC exercises are prescribed during posi- tions that exceed 50° of knee flexion.

In conclusion, quadriceps strengthening starts with OKC and CKC exercises, each in a specific ROM, but progressively the programme continues to more and more CKC exercises in a functional ROM. As mentioned before, selective weakness in eccentric quadriceps muscle strength is fre- quently observed in PFPS patients. Subsequently eccentric training should be emphasized during treatment. However since CKC exercises inherently demand eccentric quadriceps activity, using this type of exercise automatically places suffi- cient focus on the eccentric training mode.

Vastus medialis obliquus assessment In addition to an atrophy of the quadri-

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Medial head of gastroc- nemius