DIAGNOSIS

ceps as a whole, selective atrophy of the vastus medialis (VM) is frequently observed in PFPS. The role of the VM, and especially the oblique part of the VM, namely the vastus medialis obliquus (VMO), is a medial pull of the patella. This medial pull is crucial for a proper patellar alignment with respect to the femur dur- ing knee motion. Consequently, patients with a selective atrophy of the VMO have a significant greater chance of a malalign- ment of the patellofemoral (PF) joint. This malalignment results in higher PF stress, leading to PFPS. It is vital therefore that the therapist focuses on the possible pres- ence of selective atrophy of the VMO dur- ing clinical examination. If this hypotro- phy is substantial, it can easily be observed clinically and measured by thigh circumference measures 2-3 cm proximal to the patella. In some PFPS patients the VMO hypotrophy is less visual detectable, and can only be seen during quadriceps contraction. Clinical examination will reveal that these patients are not able to generate a solid contraction of the VMO while contracting their quadriceps muscle. In these patients the muscular balance between the medial part of the quadriceps (VMO) and the lateral part (vastus later- alis) is disturbed. The focus of the rehabil- itation programme should be to restore this muscular balance as fast as possible.

VMO strengthening Many exercises have been proposed in the past to selectively strengthen the VMO. Several studies showed that in no single exercise the activity of the VMO is signifi- cantly greater than the activity of the vas- tus lateralis. The only known possible way to selectively strengthen the VMO is by electrical stimulation. Based on the liter- ature we suggest the use of electrical stimulation in patients with a marked hypotrophic VMO with 18 seconds stimula- tion and 25 seconds rest for 20 minutes twice a day. Werner et al (8) showed this electrical stimulation programme was ben- eficial in 66% of the treated PFPS patients regarding pain and return to athletic activities after a 10 week programme. In addition, these authors showed that the clinical improvement was maintained at three and a half years follow up.

NEUROMUSCULAR COORDINATION In addition to strength problems, the ade- quate time of activation of the quadriceps

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muscle, and its components, is frequently disturbed in PFPS. Whereas in normal sub- jects the VMO is activated first during quadriceps contraction, several studies have shown that in PFPS patients the VL is the first to activate (9,10). This dysfunc- tion in the proper timing between the dif- ferent components of the quadriceps mus- cle (VMO/VL) is considered a critical factor in the malalignment of the patella. However in contrast to strength assess- ment the evaluation of the neuromuscular coordination is rather complicated.

Neuromuscular assessment While EMG measurements can assess this neuromuscular coordination very accurate- ly, in a clinical practice however (with no EMG measurements), this assessment can only be performed by tactile examination and is scientifically questionable. The ther- apist places his/her fingers on the muscle belly of the VMO and VL and asks the patient to contract the quadriceps. Normally no timing difference is tactilely noticed between both muscle bellies.

Encouraging neuromuscular coordination In some PFPS patients however, a marked delayed onset of the VMO is evident on palpation. In these patients, the aim of the training should focus on gathering a simultaneous activation of VMO and VL during quadriceps activity. A popular pro- gramme, developed by J. McConnell (1986), incorporates exercises with spe- cial emphasis on the normalisation of the neuromuscular coordination. These are initially carried out during comfortable conditions (sitting or lying positions) and then progress (if the sequence of the VMO/VL timing is correct) to more diffi- cult and functional positions specific to the patient’s activity or sport (2,3).

Studies have shown that after a 6-week treatment programme, following the prin- ciples described above, not only was there a reduction of symptoms, but this was associated with a significant change in timing onset of VMO compared to VL (11).

Muscle flexibility The next assessment of a PFPS patient should focus on muscular flexibility. It must be mentioned that a loss of flexibili- ty of the quadriceps, hamstrings or iliotib- ial band creates abnormal patellofemoral stresses during sports or daily life activi- ties, and in this way predispose patients

to PFPS. This implies that thorough stretching is needed in patients with tight muscles around the PF joint.

ALIGNMENT DYSFUNCTIONS In addition to the muscular assessment, a systematic evaluation of the alignment of the PF joint and the lower limb is indis- pensable in the evaluation of the PFPS patient.

Lower limb alignment An evaluation of lower limb alignment should include both a static and dynamic evaluation of the entire leg. The patient needs to stand and walk barefoot, whilst lower extremity malalignment and func- tional abnormalities are checked. In case of a functional abnormality it is essential to identify the cause for this compensato- ry mechanism (eg. muscle weakness, mus- cle tightness, patellar hypermobility). Simply stated, attention should be given to the evaluation of the ankle and foot and the knee and pelvis during the lower limb alignment assessment. During this lower limb evaluation, attention should also be given to leg length discrepancies, increased femoral and tibial rotation, and intrinsic imbalances of the foot. Studies have shown that alterations in these para- meters can lead to increased torsional and transverse forces on the patella (12, 13). Restoring the correct postural alignment or movement is a prerequisite for a suc- cessful long term non-operative treat- ment. Thus, it is evident that an observed dysfunction in alignment needs to be treated first. Only after successful man- agement of this dysfunction other aspects of the rehabilitation process like muscular strengthening seems advisable.

Patellofemoral joint alignment Other than the lower limb evaluation, the evaluation of the PF joint only focuses on the PF joint. In 1986, McConnell (3) iden- tified four components of the patella that need to be evaluated: glide, medio-lateral tilt, antero-posterior tilt and rotation. Unfortunately, the results of several stud- ies have shown that this clinical investi- gation has a fair intra-rater and poor inter-rater reliability (14). Therefore, it is advised that the examination is based on a radiological investigation (radiographs and computerised tomography). Despite this, we believe that a clinical assessment of the PF joint alignment is necessary since this examination can obtain addi-

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