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Year : 2019  |  Volume : 19  |  Issue : 3  |  Page : 92-97

Arthroscopic patellar denervation for patellofemoral (anterior knee pain) in young patients: Indications and outcome

1 Department of Orthopedics and Sports Injury, Apex Hospital, Jaipur, Rajasthan, India
2 Department of Orthopedics, SMS Medical College, Jaipur, Rajasthan, India

Date of Submission04-May-2020
Date of Decision04-Jun-2020
Date of Acceptance23-Jul-2020
Date of Web Publication21-Aug-2020

Correspondence Address:
Prof. Mahesh Chand Bansal
Department of Orthopedics, SMS Medical College, Jaipur, Rajasthan
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DOI: 10.4103/sjsm.sjsm_5_20

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Introduction: Anterior knee pain mainly affects middle age group especially those who have structural malalignment of lower limbs. There is no consensus on the treatment in those who have idiopathic anterior knee pain with normal or mild structural lower limb malalignment.
Materials and Methods: Arthroscopic peripatellar denervation was done in 30 patients (40 knees) from January 2017 to July 2019. All patients were assessed pre- and post-operatively by Kujala and Werner functional knee score.
Results: Kujala score was improved from 70.4 (45–84) preoperatively to 93.3 (75–100) at 6 months (P < 0.05). Werner anterior knee pain score improved from 29.56 (17–37) to 44.7 (32–50) at 6 months (P < 0.05). No significant improvement was seen in both scores after 6 months. Excellent results were obtained in all patients except those had excessive femoral anteversion and full-thickness cartilage defect of the patella.
Conclusion: We concluded from this study that arthroscopic peripatellar denervation is a promising treatment in young patients with no or minimal structural abnormality.

Keywords: Anterior knee pain, arthroscopic peripatellar denervation, chondromalacia patellae

How to cite this article:
Jain JK, Bansal MC, Upadhyay R, Sharma A, Chandra A, Siddharath S.P.. Arthroscopic patellar denervation for patellofemoral (anterior knee pain) in young patients: Indications and outcome. Saudi J Sports Med 2019;19:92-7

How to cite this URL:
Jain JK, Bansal MC, Upadhyay R, Sharma A, Chandra A, Siddharath S.P.. Arthroscopic patellar denervation for patellofemoral (anterior knee pain) in young patients: Indications and outcome. Saudi J Sports Med [serial online] 2019 [cited 2020 Oct 20];19:92-7. Available from: https://www.sjosm.org/text.asp?2019/19/3/92/292947

  Introduction Top

Anterior knee pain mainly affects middle age group people, and females are two times more commonly affected than males.[1],[2] Patients with anterior knee pain often have difficulty in climbing stairs, squatting, and getting up from chair. They usually do not have any difficulty in walking. Knee examination reveals no tenderness along the knee joint line. Crepitus may be felt during knee movement. We have observed that tenderness along the lateral patellar facet and lateral femoral condyle is a specific sign (lateral compartment hyperpressure sign) in these patients [Figure 1]. The causes of anterior knee pain can broadly be divided into three categories, idiopathic, local, and structural causes. Idiopathic cases are those cases where no lower limb structural abnormality can be identified. Local causes include patellar instability, patellar tendonitis, and traumatic patellar cartilage damage. Anterior knee pain secondary to lower limb structural abnormalities is the most common presentation. These include flat feet, inward looking patellae, excessive femoral anteversion, excessive tibial external rotation, and genu varum/valgum.
Figure 1: Lateral compartment hyperpressure sign: On pressing over the lateral femoral condyle after displacing patella laterally patients feels severe pain

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Innervation of the anterior knee area shows a highly variable distribution, so selective neurotomy fails to provide significant pain relief.[3],[4] In this study, we are describing indications and results of arthroscopic peripatellar neural ablation in selected patients.

  Materials and Methods Top

This study was conducted at a tertiary care hospital from January 2017 to July 2019. Thirty (40 knees) patients were enrolled in the study. Inclusion criteria were:

  • Patients with anterior knee pain without joint line tenderness
  • Patients with anterior knee pain without patellar instability
  • Patients with anterior knee pain without patella alta/baha
  • Patients with anterior knee pain with failed conservative treatment.

All patients were evaluated in detail for patellar instability, ligament laxity, and any deviation from normal limb alignment. Detailed clinical examination [Table 1] included test for excessive femoral anteversion [Figure 2], patellar instability, coronal plane deformities of legs, inward looking patellae [Figure 3], flat feet, and tendoachilles tightness [Figure 4]. All patients were assessed for patellar instability by apprehension test, patellar tilt, and patellar glide test. Patients with a known history of patellar dislocation and ligament laxity were not included in the study. Patients with excessive femoral anteversion with excessive hip internal rotation (>55°) were not included in the study. Radiological assessment included X-ray in axillary, anterior-posterior and lateral view, and magnetic resonance imaging of the involved knee [Figure 5]. Ethical committee approval was taken, and written informed consent was taken from all the patients for publishing the results.
Table 1: Clinic-radiological data of the cohort

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Figure 2: Test for excessive femoral anteversion: Excessive femoral anteversion causing more internal rotation of the hip joint on the right side

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Figure 3: Inward looking patellae

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Figure 4: Flat feet and TA tightness

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Figure 5: Sagittal (a) and axial (b) scans in anterior knee pain patients showing patellar cartilage changes

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All patients were operated by a single surgeon, and arthroscopic peri-patellar neural ablation was done in all patients using 4–6 portals. In 9 patients, additional lateral release was done as lateral tightness was present (patellar tilt 0° or less) on clinical examination. Werner functional knee score and Kujala score were calculated in all patients, pre- and post-operatively at 1 and 6 months postsurgery.

Surgical technique

4–6 portal arthroscopic neural ablation was done using radiofrequency (RF) ablator in all patients by a single surgeon. Apart from routine anterolateral and anteromedial portals, 2–4 superolateral and superomedial portals were made [Figure 6] for neural ablation along the medial and lateral borders [Figure 7]. We routinely made medial and lateral portals at the level of superior pole of patella for effective ablation. This thermal ablation should be avoided in the region of the patellar tendon because most of the vessels reaching the patella enter through this region and injury to these vessels may cause patellar necrosis.
Figure 6: Accessory portals for peripatellar ablation

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Figure 7: Arthroscopic pictures showing radiofrequency ablation along the medial border (a), along the lateral border (b), along the superomedial corner (c)

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Fat pad from the distal pole of patella was shaved off to increase visualization. Finger pressure was used to move the patella to bring the area to be ablated over ablator probe for easy ablation. Advanced cartilage damage was treated by shaver to make it smooth, and then, RF ablation was done.

In addition, lateral release was also done in 9 patients who had lateral tightness on tilt and glide test. Chondral changes of patella with loose cartilage fragments were also ablated. Postoperatively, all patients were allowed to walk with support. Quadriceps and range of motion exercises were started in the immediate postoperative period. Medial arch support insoles were given to all patients of flat feet. All patients with flat feet and TA tightness were put on the foot intrinsic muscle exercises and gastrocnemius stretching exercises postsurgery.

  Results Top

Forty knees in 30 patients (18 females 12 males) were included in this retrospective study with average follow-up of 14 months (9–30 months). Records of all patients were assessed. Fifteen patients had pain in both knees. Ten patients were operated on their both legs. They had bilateral knee pain and encouraged by the result of first surgery they got their other knee operated. Five patients although satisfied with the result of the surgery did not get their second knee operated results are tabulated in [Table 2].
Table 2: Patient's data

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The average age of cohort was 35 years (19–46 years). All patients had failed conservative treatment of at least 6 months. The clinical manifestations included recurrent swelling and pain in the knee joint; difficulty in ascending/descending stairs, squatting down, and standing up from a sitting position.

Werner anterior knee pain score and Kujala score were calculated preoperatively and postoperatively at 6 months and 1 year. Twelve patients had arthroscopic findings of grade 1–3 patellar chondral damage, whereas three patients had full-thickness cartilage defect. Kujala score was improved from 70.4 (45–84) preoperatively to 93.3 (75–100) at 6 months (P < 0.05). Werner anterior knee pain score improved from 29.56 (17–37) to 44.7 (32–50) at 6 months (P < 0.05). No significant improvement was seen in both scores after 6 months. Excellent results were obtained in all patients except those who had excessive femoral anteversion and/or full-thickness cartilage defect of the patella (7 patients). Five patients with excessive femoral anteversion also had inward looking patellae. Average Werner score of these 7 patients improved from 25.42 (17–32) to 37.42 (32–38) Kujala score also improved only moderately in these patients from 50.85 (45–62) to 79.8 (76–84). Two patients with least improvement had constellation of excessive femoral anteversion, inward looking patellae, and Grade IV cartilage defect of patella. No serious complications such as knee stiffness or infection were noted in any patient after surgery. Quadriceps atrophy was observed in 22 patients after surgery which was improved with quadriceps building exercises in all patients. Patellar necrosis was not observed in any case.

  Discussion Top

Pain relief by neural ablation is not a new concept. Its role in spinal radiculopathy and trigeminal neuralgia is well-known. Møller and Helmig[4] tried selective neurotomy of the patellar branch of the saphenous nerve for anterior knee pain relief, but the results were not encouraging as there is substantial anatomical variation in the nerves which carry pain from patella. The results of selective neurotomy for anterior knee pain have been disappointing by other authors also.[4] Failure of selective neurotomy in reliving patellar pain can be explained by the fact that the knee and patella are richly innervated from both medial and lateral side.

Neural anatomy around patella

Patella is innervated by medial and lateral patellar nerves.[3],[4] Peripatellar soft tissues, periosteum and degenerative subchondral bone are rich in afferent nerve fibers.[5] Rich neural innervation of the soft tissues in peripatellar region has been reported by many immunohistochemical studies.[6],[7]

Lateral aspect of the knee is innervated by tibiofibular branch of the peroneal nerve, the lateral retinacular nerve, and the lateral femoral cutaneous nerve. Sensory innervation of the medial aspect of the knee includes the infrapatellar branch of the saphenous nerve, the medial retinacular nerve, and the medial and anterior cutaneous nerves of the thigh. The lateral and medial retinacular nerves provide sensation to the knee joint, whereas the other five nerves innervate the skin of the knee joint.[8]

Role of patellar denervation in relief of anterior knee pain after total knee arthroplasty is well established, and cautery ablation of peripatellar tissue is a routine practice among arthroplasty surgeons.[9],[10],[11] Arthroscopic RF ablation can damage healthy chondrocytes as temperature may rise up to 50° or more so continuous irrigation and momentary application is enormously important.[12]

We arthroscopically release lateral retinaculum in 11 patients. Lateral retinacular tightness is very common in patients with anterior knee pain, as described by Ficat et al.[13] as excessive lateral pressure syndrome. A neural model for anterior knee pain suggested by Sanchis-Alfonso et al.[14],[15] also focuses on the lateral compartment of the knee. They have suggested hyperinnervation into the lateral retinaculum as a possible source of anterior knee pain in the young patient.[14],[15] These authors showed a higher innervation pattern in the lateral retinaculum than the medial retinaculum in patients with anterior knee pain. Most of the nociceptive fibers and neurological structures have been localized in the peripatellar tissues about 0.75 and 1.5 mm from the articular surface.[16] Arthroscopic ablators can cause lesion up to depth of 1.5 mm, so nociceptive fibers are amenable to be injured by these ablators without causing damage to healthy chondrocytes.

Our criteria for lateral release were patellar tilt 0° or less and medial translation of patella one quadrant or less on glide test. How lateral release can help in reliving anterior knee pain is a matter of debate at present, and its mechanism cannot be explained with certainty. We believe that lateral release help by relieving pressure on the lateral facet of the patella and dividing afferent nerves on the lateral border of the patella.

We can divide the patients of anterior knee pain into two categories. The first category belongs to patients with obvious structural malalignment and patients with anterior knee pain with structurally normal lower limb fall in the second category. Majority of patients fall in between these two categories, i.e., having anterior knee pain with minimal structural abnormality. We believe that ideal candidate for arthroscopic neural ablation would be one with no or minimal lower limb structural abnormality. We excluded patients with a history of patellar dislocation and excessive femoral anteversion (hip internal rotation >55°). Patients of anterior knee pain with flat feet, with or without lateral tightness were among the most satisfied patients following surgery. Eight patients with no obvious lower limb malalignment also improved significantly. Least improvement was seen in patients with inward looking patellae with excessive femoral anteversion and full-thickness patellar cartilage defect.

  Conclusion Top

We concluded from this study that arthroscopic peripatellar denervation is a promising treatment in young patients with no or minimal structural abnormality. It is a simple procedure which also gives a chance to see and treat other intra-articular pathology such as cartilage lesions and plica syndrome which are difficult to interpret on clinicoradiological examination. It is low volume study with mid-term results only. Large randomized studies are needed to recommend the method firmly.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Boling M, Padua D, Marshall S, Guskiewicz K, Pyne S, Beutler A. Gender differences in the incidence and prevalence of patellofemoral pain syndrome. Scand J Med Sci Sports 2010;20:725-30.  Back to cited text no. 1
Fulkerson JP, Arendt EA. Anterior knee pain in females. Clin Orthop Relat Res 2000;(372):69-73.  Back to cited text no. 2
Maralcan G, Kuru I, Issi S, Esmer AF, Tekdemir I, Evcik D. The innervation of patella: Anatomical and clinical study. Surg Radiol Anat 2005;27:331-5.  Back to cited text no. 3
Møller BN, Helmig O. Patellar pain treated by neurotomy. Arch Orthop Trauma Surg 1984;103:137-9.  Back to cited text no. 4
Wojtys EM, Beaman DN, Glover RA, Janda D. Innervation of the human knee joint by substance-P fibers. Arthroscopy 1990;6:254-63.  Back to cited text no. 5
Biedert RM, Sanchis-Alfonso V. Sources of anterior knee pain. Clin Sports Med 2002;21:335-47, vii.  Back to cited text no. 6
Sanchis-Alfonso V, Roselló-Sastre E. Anterior knee pain in the young patient—what causes the pain? “Neural model”. Acta Orthop Scand 2003;74:697-703.  Back to cited text no. 7
Vega J, Golanó P, Sanchis-Alfonso V. Arthroscopic patellar denervation for anterior knee pain. In: Sanchis-Alfonso V, editors. Atlas of the Patellofemoral Joint. London: Springer; 2014.  Back to cited text no. 8
Altay MA, Ertürk C, Altay N, Akmeşe R, Işıkan UE. Patellar denervation in total knee arthroplasty without patellar resurfacing: A prospective, randomized controlled study. Orthop Traumatol Surg Res 2012;98:421-5.  Back to cited text no. 9
van Jonbergen HP, Scholtes VA, van Kampen A, Poolman RW. A randomised, controlled trial of circumpatellar electrocautery in total knee replacement without patellar resurfacing. J Bone Joint Surg Br 2011;93:1054-9.  Back to cited text no. 10
Saoud AM. Patellar denervation in non-patellar resurfacing total knee arthroplasty. Pan Arab J Orthop Trauma 2004;8:25.  Back to cited text no. 11
Ahrens P, Mueller D, Siebenlist S, Lenich A, Stoeckle U, Sandmann GH. The influence of radio frequency ablation on intra-articular fluid temperature in the ankle joint-a cadaver study. BMC Musculoskelet Disord 2018;19:413.  Back to cited text no. 12
Ficat P, Ficat C, Bailleux A. [External hypertension syndrome of the patella. Its significance in the recognition of arthrosis]. Rev Chir Orthop Reparatrice Appar Mot 1975;61:39-59.  Back to cited text no. 13
Sanchis-Alfonso V, Roselló-Sastre E, Monteagudo-Castro C, Esquerdo J. Quantitative analysis of nerve changes in the lateral retinaculum in patients with isolated symptomatic patellofemoral malalignment. A preliminary study. Am J Sports Med 1998;26:703-9.  Back to cited text no. 14
Sanchis-Alfonso V, Roselló-Sastre E, Revert F. Neural growth factor expression in the lateral retinaculum in painful patellofemoral malalignment. Acta Orthop Scand 2001;72:146-9.  Back to cited text no. 15
Vega J, Palacín A, Maculé F, Lozano L, Golanó P, Pérez-Carro L, et al. Localización de los receptores de dolor en el tejido blando perirrotuliano. Estudio Inmunohistoquímico. Cuadernos de Artroscopia 2008;15:8-13.  Back to cited text no. 16


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]

  [Table 1], [Table 2]


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