Patellaplasty , as an Alternative to Replacing Patella in Total Knee Arthroplasty

Aim: In tricompartmental osteoarthritis of the knee, the patellofemoral articulation is severely affected due to degenerative changes. Patellaplasty is done as a part of total knee arthroplasty in these cases to smoothen the articular surface of patella. However, an ideal technique with easy reproducibility has been scarcely reported for the same. Method: We describe a method of using electrocautery and power saw with thin blades for patellaplasty. Results: Using this technique, we have produced results, which are comparable with cases where patellar resurfacing has been done. Conclusion: This described method for patellaplasty is easy with good reproducibility.


Introduction
There has been significant progress in surgical design and technique, which has led to improved function for patients after total knee arthroplasty (TKA).The modern implants have ensured that more than 90% of modern primary total knee replacements survive for at least fifteen years [1].However, the problems related to the patellofemoral joint in unresurfaced patellae [2] such as progressive degenerative changes on the lateral facet occurred in 85% of patellae [3] [4], and the increased incidence of anterior knee pain [5] have not been eliminated.These lead to continued symptoms and reduced quality of life for the patient [6] [7].
To deal with the patellofemoral joint, two schools of thought have existed-patellar resurfacing wherein the native articular surface of the patella is replaced with poly and patellaplasty where the native articular surface is kept intact.When the decision is made not to resurface the patella, caution must be exercised to assure that the articular surface of the patella is smoothened and that the osteophytes are thoroughly excised.Various techniques are described in literature ranging from use of electocautery [8], bone nibblers, surgical knife, drills [9], facetectomy [10] etc. alone or in combination.We describe a technique for patellaplasty using electrocautery and power saw.

Surgical Technique
The same senior surgeon performed the procedure and the technique was the same in all cases.Suitable anaesthesia was administered and the procedure was performed under tourniquet.After ensuring all aseptic precautions, a midline patellar incision was made.The incision was deepened in layers till the fascia of quadriceps is reached.Arthrotomy was performed using the midvastus approach, and the vastus medialis was dissected through its substance.The patella was everted and held securely with the help of towel clip.A narrow Langenback's retractor was held on the superior aspect of the patella to protect the soft tissues (Figure 1).
Next, the peripatellar soft tissues were cauterized with the help of thermal electrocautery to denervate the patella and also to elevate the margins of patella for better demarcation (Figure 2).
The hypertrophied lateral facet, which was to be excised, was demarcated with the help of electrocautery.This also helped in preventing excessive resection of the lateral facet (Figure 3).
The hypertrophied facet was excised with the help of power saw.The Lagenback's retractor was used to protect the quadriceps tendon from lacerations due to the power saw.The femoral condyles were also protected from the power saw with the help of a periosteum elevator (Figure 4).
Similarly, the osteophytes over the superior, inferior and lateral borders of patella were excised in order to create a uniform margin (Figure 5).Next, the articular surface of the patella was smoothened using a power saw.This ensured the articular surface of the patella did not cause abrasive wear over the implants (Figure 6).The finesse of the articular surface was confirmed by placing a finger on it.If it feels rough, it is further smoothened with the help of saw (Figure 7).

Discussion
In total knee arthroplasty for tricompartmental osteoarthritis of the knee, resurfacing of the patella has remained       an issue of debate since a long time [11]- [16].There have been substantial studies which have reported that the procedure has improved pain relief and ability to climb stairs [12] [16], and these have led to surgeons resurfacing the patella as a part of total knee arthroplasty.On the other hand, the presence of early and late complications [12] [17] associated with the procedure has renewed an interest in not resurfacing the patella in total knee arthroplasty.
Hasegawa and Ohashi [18] have published long-term clinical results and radiographic change in the nonresurfaced patella after total knee arthroplasty (78 knees followed for mean 12 years) and have reported excellent results in these patients with respect to pain and patellar subluxation.No patient needed revision surgery for patellar problems.Authors [19] performed similar studies where 199 osteoarthrititc knees were treated with total knee replacement using Low Contact Stress (LCS) knee prosthesis and patellaplasty and none of the patients had resurfacing of patella.None of the patients required resurfacing during the follow-up and there were no reports of significant anterior knee pain, dislocation, maltracking or fractured patella.
Cho et al. [20] retrospectively reviewed 43 cases (35 patients) of total knee arthroplasty with patellar retention performed by a single surgeon over seven years with an average follow-up period of 54 months.According to their study, there was neither significant difference in terms of range of motion, and stair climbing ability nor of patellar shift among all three groups.Total knee arthroplasty with patellaplasty provided satisfactory results without significant problems regardless of the preoperative degree of patello-femoral arthritis.
In situations where the patella was not resurfaced, various techniques had been described for patellaplasty.Yercan et al. [10] described partial lateral patellar facetectomy for isolated patellofemoral arthritis over a period of ten years with mean follow-up of 8 years.They concluded that partial lateral facetectomy was relatively simple and effective surgical treatment for middle-aged to elderly active patients with isolated lateral patellofemoral osteoarthritis who wanted to maintain activity level.Other techniques include the use of electrocautery [8] [21], drilling [9] with sharp tipped drill at the proximal or distal side of the patella to decompress the subchondral bone, use of bone nibblers to excise the osteophytes or a combination of any of these described methods.
This report lacks a head to head comparison with a particular technique.It aims to highlight a combination of surgical technique.Our technique, which employs the use of electrocautery to demarcate the patella rim and the use of a power saw to excise the osteophytes, smoothens the articular surface and excise the hypertrophied lateral facet is an easy and reproducible technique which eliminates all complications of patellar resurfacing.It proves to be a suitable alternative to replacement of patella in total knee arthroplasty and also reduces patients' total cost, a definite step forward.

Figure 1 .
Figure 1.Patella everted with towel clip, Langenback's retractor held on the superior aspect of the patella to protect soft tissues.

Figure 2 .
Figure 2. Peri-patellar soft tissues cauterized with the help of thermal electrocautery to denervate for better demarcation.

Figure 3 .
Figure 3.The hypertrophied lateral facet, demarcated with the help of electrocautery.

Figure 4 .
Figure 4. Femoral condyles protected with the help of a periosteum elevator.

Figure 5 .
Figure 5. Osteophytes over the superior, inferior and lateral borders of patella were excised.

Figure 6 .
Figure 6.Articular surface of the patella smoothened using a power saw.

Figure 7 .
Figure 7. Finesse of the articular surface confirmed by finger.