Table 1.
Summary of the data extracted from the included studies, presented in a chronological order based on the publication dates
| Authors | LOE | N° knees | Mean age (years) | Preoperative diagnosis | Main treatment | Mean follow-up (months) | Radiological results | Clinical and functional results | Complications occurred |
|---|---|---|---|---|---|---|---|---|---|
| Merkow et al. 1985 [9] | IV | 12 | 62 (46–70) | Patella maltracking after primary TKA | -10 proximal realignment (Insall procedure)-1 proximal realignment combined with components revision-1 lateral retinaculum release only | 34 (24–57) | Patella was centrally located in the trochlear groove in 10 knees and slightly tilted laterally in 2 | The results using The Hospital for Special Surgery knee-rating scale were excellent in 10 knees and good in 2. The average score was 89 (range 84–92), an increase of 27 (range 18–40) from the preoperative score. Pain was relieved in all but one patient, that had a mildly painful click during active extension | 1 superficial skin necrosis healed with local care; 1 horizontal fatigue fracture of the patella |
| Grace et al. 1987 [48] | IV | 25 | 72 (60–86) | Patella maltracking after primary TKA |
-14 proximal realignment (Insall procedure)-9 combined proximal and distal realignment (modified Hauser procedure) -2 components revision |
50 (24–125) | 20 knees had a normal patellar tracking, 5 had recurrent subluxation | The average Hospital for Special Surgery knee-rating scale in patients treated with proximal realignment was 72 (range 39–88), with combined realignment 79 (range 55–93), with component revision 86 (range 84–88). Pain was reduced in all knees, 16 had no pain, 5 mild pain, 4 moderate pain | Flexion decreased from an average of 105° (range 80°–130°) to 93° (range 45°–130°); 2 patellar tendon ruptures; 1 loss of staple fixation; 2 late deep infection necessitated component removal and arthrodesis |
| Bocell et al. 1990 [49] | IV | 2 | / | Patella maltracking after primary TKA | Arthroscopic lateral retinaculum release | 18–22 | All knees achieved normal patellar tracking | All patients had clinical and functional improvement without a specific score system declared | None |
| Johnson et al. 1990 [50] | IV | 5 | 68.5 (57–81) | Patella maltracking after primary TKA | Arthroscopic lateral retinaculum release and lysis of parapatellar adhesions | 16 (3–32) | All knees achieved normal patellar tracking | The mean preoperative knee score* was 48, and improved to 83, representing a 73% improvement. The mean preoperative pain score was 25 (out of 50) and improved to 45, representing an 80% improvement | None |
| Kirk et al. 1992 [51] | IV | 15 | 67 (54–77) | Patella maltracking after primary TKA | Lateral retinaculum release and medialization of the tibial tubercle (modification of the Trillat procedure) | 24 (12–48) | Patella properly positioned in the femoral component groove in all but one patient, had some residual patellar tilt but there was no subluxation | The results using the Hospital for Special Surgery knee-rating scale averaged 82 (range 61–95). 11 patients rated good or excellent, 1 rated fair, 2 rated as failures (1 had persistent pain of unknown origin, 1 had a nonunion of the osteotomy) | 1 nonunion of the osteotomy; 1 patient had loss of flexion (preoperative 90° preoperative to 80° postoperative); 1 late-onset infection |
| Chin et al. 2004 [52] | IV | 39 | 68 (27–91) | Patella maltracking after primary TKA |
-12 lateral retinaculum release only -14 lateral retinaculum release and advancement of the VMO -1 advancement of the VMO only -4 V–Y quadricepsplasty and lateral retinaculum release -7 V–Y quadricepsplasty, lateral retinaculum release and advancement of the VMO -1 varus tibial osteotomy (to correct a 30° valgus malunion of the proximal tibia) |
38,4 (24–84) | All but one knees achieved normal patellar tracking, 1 had recurrent dislocation with an associated quadriceps tendon rupture | The mean prerevision Knee Society Score was 34 (range 0–74) and the mean prerevision Knee Society function score was 35 (range 0–100), the mean postrevision scores were, respectively, 77 and 54, with average improvements 43 and 19 | 1 recurrent dislocation with quadriceps tendon rupture; 1 lateral skin flap necrosis; 1 patella fracture and osteonecrosis; 1 superficial wound infection; 1 deep infection |
| Campbell et al. 1995 [18] | IV | 14 | 70.4 (38–88) | Patella maltracking after primary TKA |
- 6 lateral retinaculum release - 4 lateral retinaculum release and medial plication - 2 lateral retinaculum release and tibial tubercle realignment -1 tibial component revised -1 polyethylene tray revised and distal realignment |
14–44 | Undeclared | 10 patients had a resolution of their symptoms (undeclared score system), 2 some improvement, 1 no change and 1 had a deep infection | 1 deep infection managed by debridement and long-term antibiotics |
| Whiteside et al. 1997 [53] | IV | 31 | / | Patella maltracking after primary TKA |
a. 10 modified Roux-Goldthwait procedure b. 3 medial transfer of the medial 1/2 of the patellar tendon c. 18 medial tibial tubercle transfer |
12 | All knees achieved normal patellar tracking. No late patellar subluxations or dislocations have occurred | All patients had clinical and functional improvement without a specific score system declared |
a. none b. none c. 3 hematomas of which 2 required surgical evacuation and in 1 late-onset deep infection developed that required removal of the implants, debridement and revision arthroplasty |
| Asada et al. 2007 [54] | V | 1 | 82 | Patella maltracking after primary TKA | MPFL reconstruction | 24 | The knee achieved normal patellar tracking | The patient had clinical and functional improvement without a specific score system declared | none |
| Incavo et al. 2007 [55] | IV | 22 | 69 (42–88) | Patella maltracking after primary TKA with one of more malrotated components | Full-components revision (2 femoral components only) | / | All but 2 patellae tracked centrally | The prerevision to postrevision Knee Society Score improved from 42 (range 10–62) to 77 (range 65–95), whereas the Knee Society function scores improved from 38 (range 5–60) to 49 (range 10–85). 3 patients had moderate pain, 2 had mild pain, the remaining had no pain | 1 mediolateral laxity greater than 10°; 1 patella osteonecrosis because of patella remnant was 8 mm thick; 1 deep vein thrombosis |
| Price et al. 2009 [56] | IV | 5 | 68.8 (60–76) | Patella maltracking after primary TKA |
- 4 lateral retinaculum release, components revision and Fulkerson osteotomy -1 lateral retinaculum release and Fulkerson osteotomy only |
29.7 | All knees achieved normal patellar tracking | The average preoperative Knee Score was 70,5 that improved to 85.0. No patients complained of any pain | 1 cellulitis secondary to venous stasis that resulted in a deep infection requiring irrigation and debridement with resolution |
| Nakajima et al. 2010 [57] | V | 1 | 74 | Patella maltracking after primary TKA | Elmslie-Trillat procedure (lateral retinaculum release, plication of the medial retinaculum, and medial displacement of the tibial tubercle) | 12 | Patella was slightly tilted laterally but there was no evidence of patellar maltracking or subluxation | The patient had clinical and functional improvement without a specific score system declared | none |
| Lakstein et al. 2010 [58] | IV | 24 | 68 (53–83) | Patella maltracking after primary TKA with one of more malrotated components | Full-components revision (1 femoral component only) | 37 (24–65) | All knees achieved normal patellar tracking | Mean Knee Society Score improved from 33 ± 18 preoperatively to 82 ± 6 at 6 months and 80 ± 8 at last follow-up. Only 1 patient complained of constant significant pain | 1 undisplaced patella fracture treated conservatively; 1 pulmonary embolism |
| Pietsch et al. 2011 [59] | IV | 14 | 64 (41–73) | Patella maltracking after primary TKA with isolated internal femoral component malrotation | Components revision (7 patients had also patella resurfacing) | 57 (46–89) | All knees achieved normal patellar tracking | The mean Knee Society Score and Function increased from 52 (range 26–69) and 65 (range 30–90) to 85 (range 66–94) and 84 (range 65–100). The mean Hospital for Special Surgery Score increased from 63 (range 51–74) to 83 (range 68–91). 6 knees were rated excellent, 5 good, 1 fair | none |
| Van Gennip et al. 2012 [60] | IV | 9 | 75 (60–83) |
a. 6 Patella maltracking after primary TKA b. 3 Patella maltracking after revision TKA |
- 7 MPFL reconstruction and lateral retinaculum release -2 MPFL reconstruction, lateral retinaculum release, and tibial tuberosity transfer |
33 (10–48) | Median patellar displacement and tilt improved from 29 mm (range 0–44) and 45° (range 23–63) preoperatively to 0 mm (range 0–9) and 15° (range -3°-21°) | Median VAS satisfaction was 8 (range 5–9) and only one patient reported twice having a feeling related to subluxation | none |
| Goto et al. 2014 [61] | V | 1 | 78 | Patella maltracking after primary TKA | MPFL reconstruction and lateral retinaculum release | 12 | The knee achieved normal patellar tracking | The patient had clinical and functional improvement without a specific score system declared | none |
| Lamotte et al. 2016 [62] | IV | 6 | 77 (70–87) |
a. 4 Patella maltracking after primary TKA b. 2 Patella maltracking after primary TKA with components internally rotated |
a. 4 MPFL reconstruction b. 1 MPFL reconstruction and components revision; 1 isolated MPFL reconstruction because of the high anesthesia risk |
23(6–46) | Patellar tilt was less in all patients but 1, that had no change on the radiographs | None of the patients had a recurrence of the dislocation at the last follow-up and the functional scores (Kujala and subjective IKDC) improved in all patients except one, that had minimal clinical improvement and continued to experience pain with a feeling of patellar instability | none |
| Matar et al. 2020 [63] | IV | 3 | 75,87,73 |
a. Patella maltracking after primary TKA with components internally rotated b, c. Patella maltracking after revision TKA |
a. components revision and extensor mechanism reconstruction (elevate vastus lateralis off the intermuscular septum up to the mid-thigh, lateral retinaculum release, partial release of IT band, VMP advancement) b,c. extensor mechanism reconstruction (as a.) only |
16,32,12 | All knees achieved normal patellar tracking | Clinical and functional improvement with post-operative Knee Society Score of 92,85 and 79 | none |
| Shen et al. 2020 [64] | V | 1 | 84 | Patella maltracking after primary TKA | Partial lateral patella facetectomy, lateral retinaculum release and vastus medialis restore | 12 | The knee achieved normal patellar tracking | Clinical and functional improvement with post-operative Hospital for Special Surgery Clinical Score of 85 | none |
| Warschawski et al. 2020 [65] | IV | 36 | 67 (49–78) | Patella maltracking after primary TKA with one of more malrotated components | Full-components revision | 56 (5–145) | All knees achieved normal patellar tracking, except one patient, had a recurrent dislocation episode | Clinical and functional improvement with postoperative mean Knee Society Score of 86.2 at final follow-up | 1 tibial tuberosity fracture |
| Saito et al. 2020 [66] | V | 1 | 68 | Patella maltracking after primary TKA with femoral component installed at a valgus position | Closing-wedge distal femoral varus osteotomy, MPFL reconstruction, lateral retinaculum release, patella resurfacing and substitution of the polyethylene insert | 24 | The knee achieved normal patellar tracking | The Kujala functional score and the Oxford knee score improved from 24 to 58 and from 28 to 40 | none |
*Patients were graded according to a knee rating system: 15 points were assigned for pain, 30 points for function, 10 points for deformity, and 10 points for motion. A score over 80 points represents a good result and over 90 points an excellent result