Introduction:
Genu recurvatum is a commonly acquired deformity found in many rehabilitation populations with musculoskeletal pathologies in post-polio residual paralysis (PPRP). Often it is associated with various biomechanical deficits which may include inadequate dorsiflexion in swing, dorsiflexion collapse in stance and medio-lateral ankle instability.(1)
Commonly used orthoses includes heel wedge (2), Ankle Foot Orthoses (AFO) set in dorsiflexion (2), Knee Ankle Foot Orthoses (KAFO) (2-4), Ground Reaction Ankle Foot Orthosis (5), Supracondylar KAFO (6) and Swedish Knee Cage (6) etc. However they suffer from some disadvantages e.g. Heel wedge & AFO being used only for mild genu recurvatum of up to 20 degrees, KAFO being cumbersome & locking knee mechanically may increase energy expenditure and produce un-natural gait (2), KO which do not control ankle and SKO which do not provide sitting cosmesis etc. Many orthoses have not been successfully fitted with good acceptance, less effective for moderate to severe genu recurvatum (3,4,6) and more evidence is required (7) because of few published guidelines and limited number of studies.(8,9) The aim was to check the effectiveness of an articulated knee hyperextension orthosis (KAFO) in severe genu recurvatum in terms of hyperextension control, gait parameters and energy expenditure.
Case Report:
A 63 years old male diagnosed as PPRP showed excessive hyperextension of his left knee during long standing and walking. He had 40 degrees of painful, hyperextension range at the knee and moderate, although flexible, ankle varus and foot drop. Muscle strength was poor on the left, being essentially non-functional. The right extremity showed good strength at the hip in the extensors with fair plus flexors, abductors, and rotators. The knee showed fair plusquads and hamstrings with ankle being poor. There was no contracture or shortening of limbs. He showed lateral trunk bending and circumduction gait during walking. Another complaint was discomfort and fatigue in his right leg, which had provided his primary stance support for many years. He had to limit his standing and walking time, but he could sit, climb stairs with relative discomfort.
In order to achieve stance phase support of affected limb, an orthotic design was proposed, fabricated and fitted to check the effectiveness of the design, which incorporated characteristic features like pre-flexed KAFO (Articulated Knee Hyperextension Orthosis) whose working principle was based on a couple force system (Figure 1). A free motion orthotic knee joint was used to provide swing phase flexion and sitting cosmesis. Other features include ankle in neutral position, keeping sufficient height of posterior calf which should also not interfere with sitting knee flexion, lowering antero-proximal trim line, supracondylar support, reinforcement, cut out and straps at appropriate areas as per standard Prosthetic & Orthotic guidelines.
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Fig 1: Anterior & Lateral view of KAFO with coupled force. |
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Figure No 2: (a) Without Orthosis, (b) With Orthosis, (c) Sitting cosmoses & Comfort |
The orthosis controlled knee hyperextension by not allowing the knee to go beyond neutral position i.e. the peak knee extension angle was reduced from 40 degrees to neutral during mid-stance of affected limb (Figure 2a & 2b). Gait deviations like excessive lateral trunk bending, use of ipsilateral hand to knee gait and instability was controlled with the use of orthosis as evident from OGA.
The comparison of PCI values in both conditions is given in Table 1.
Table 1: Comparison of Physiological Cost Index data (PCI) |
| Bracing Conditions |
Resting (HR |
Walking (HR) |
HR Diff |
Speed
(m/min) |
PCI |
With KAFO |
72 |
84 |
12 |
7.2 |
1.67 |
Without KAFO |
72 |
88 |
16 |
9.6 |
1.67 |
The stance: swing ratio and single limb support time is given in Table 2.
Table 2: Comparison of Stance and Swing Phase Ratio, single limb support percent from OGA |
Bracing
Conditions |
Stance : Swing |
Single Limb Support |
|
Right |
Left |
Right |
Left |
With KAFO |
72 : 28 |
80 : 20 |
14 |
13 |
Without KAFO |
74 : 26 |
86 : 14 |
13 |
10 |
PCI data revealed no difference in both conditions but the gait was found to be more natural with proper rolling of the affected limb in stance phase. Differences were found in subjects' perception of fatigue, pain and knee stability between the KAFO and no orthosis conditions. There was an improvement in stance:swing ratio.
Discussion
The principal aim of this case study was to evaluate the effectiveness of a KAFO on gait in PPRP a patient with genu recurvatum due to weakness of the quadriceps. A significant decrease in knee hyperextension (the primary outcome measure) during the stance phase of gait confirms that the KAFO was indeed effective in controlling excessive genu recurvatum. The coupled force system of the orthosis controls hyper extension of the knee and maintained the knee in pre flexed position by the anteriorly directed force of posterior cuff shell and posteriorly directed force by the anterior thigh shell (Figure 1). In poliomyelitis, often the crucial affected level is knee which needs to be stabilised. The present design is more physiological as it provides opportunity for free swing in gait cycle and also subject being stable, secure and comfortable. Earlier reports also have demonstrated success in using free orthotic knee and modifying weight bearing line with respect to anatomic knee.(1) This total contact low profile KAFO (covering 1/3rd of anterior thigh) is free from perineal discomfort and weighs less (1700 gms) as compared to that of a conventional KAFO (2200 gms).
In results, no difference in PCI was observed for braced or unbraced conditions. The gait speed was slow (7.2 m/min as compared to 9.6 m/min) with orthosis. In contrast, Boudarham et al (3) in a recent study found an increase in gait speed with orthotis use in hemiplegic patients with genu recurvatum. This may be due to the fact that, the orthosis was new to the patient. He needs a period of accommodation with orthosis. However heart rate was more stable with orthosis use. In a normal gait cycle, stance:swing accounts for 60:40 percent. Due to severe genu recurvatum the stance phase time was increased in the affected side. However, there was an improvement with orthosis and the ratio came to 80:20 from 86:14 for left side. Similarly there was an improvement in single limb support percentage with orthosis use. The reason may be controlling hyperextension to a significant degree, the time spent on affected side stance reduced and it improved the duration of swing. There was an improvement in transition of stance to swing which occur in a normal gait cycle. Hopefully a follow up could result with improving PCI parameter and speed.
Keeping the ankle in neutral position, controlled circumduction of affected left side. There was proper heel strike to forward propagation of tibia which demonstrated natural gait. The use of orthosis markedly reduced the exaggeration of movement of upper trunk and low back pain was relieved significantly. Subjective evaluation demonstrated that the orthosis was comfortable, cosmetically highly acceptable, allowing natural sitting. This can fit with any regular foot wear with standard heel. The only disadvantage being donning and doffing at first time use, but we found it comfortable after repeated use within a week.
Conclusion:
The differences found in the peak knee extension angle, knee stability and gait changes and patients compliance indicate that the present Articulated Knee Hyperextension Orthosis is effective in managing Genu Recurvatum. However a further analysis including more number of patients and revision follow up is necessary for generalising this study.
Acknowledgement:
The authors would like to thank our subject for his sincerity and cooperation throughout this case study. We would also like to thank Mrs. Joice Issac, Senior Programmer (Gait Lab) for her valuable comments.
References
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