Table 2 Results of studies performing conservative strategies

Straume‑Næsheim et al. [41]

Norway

To compare surgery (reconstruction of the medial patellofemoral ligament (MPFL-R)) with active rehabilitation in the absence of anatomical changes such as risk factors

- 61 patients (surgery, n = 30, rehabilitation, n = 31)

- Patellar instability PISS and (BHS)

- Function (PROMS): KOOS, Kujala, Cincinnati, Lysholm and Noyes Sport Activity (Baseline and 12 months)

- Home exercises and referral to physiotherapy

- VMO strengthening training program, hamstring stretching and knee neuromuscular balance. McConnell patellar brace or bandage

- PROMs (p > 0.05) comparing surgery and rehabilitation

- Persistent instability (12 months): 13 (41.9%) rehabilitation, 2 (6.7%) surgery (RR 6.3 (95% CI 1.5–25.5)

- Anterior knee pain: 6 (20%) in the surgery group

- Complex regional syndrome in the surgery group (1)

- ROM without differences between groups at follow-up

Smith et al. [40]

UK

To compare VMO strengthening with general quadriceps strengthening after first patellar dislocation

- 50 patients

- General quadriceps exercises (n = 25)

- Specific VMO exercises (n = 25)

- Instability: Norwich Patellar Instability (NPI)

- Function: Lysholm and Tegner Level of Activity

- Isometric knee extension strength in various knee ROMs (baseline, 6 weeks, 6 months and 12 months

- Standard treatment was immobilization (3–4 weeks) in an extension splint, followed by physiotherapy

- Exercise diary

- The program was aimed at reducing pain, swelling and stiffness and increasing ROM and function. Exercises designed to strengthen or recruit VMO or the group-dependent quadriceps complex

- Tegner (12 months) in the general quadriceps exercise group compared to the VMO group (p = 0.04; 95% CI − 3.0 to 0.0)

- Lysholm (p = 0.05)

- There was no statistically significant difference between groups for NPI

- 2 episodes were observed (VMO group)

- There was no statistically significant difference between groups for isometric strength

Rood et al. [21]

Netherlands

To evaluate whether taping results in better functional results and patellar stability in the short term

- 18 patients

- Bandage (n = 9)

- Immobilization with plaster (n = 9)

- Function: Lysholm Knee Scoring Scale [18] was at 1, 6 and 12 weeks and at 1- and 5-year post-dislocation

- Instability: Dislocation episodes

- Circumference of the quadriceps

- 1st week post-dislocation fixed splint. Afterwards, peripatellar taping to avoid re-dislocation (allowing 30°–40° of Flexion) or plaster

- Six weeks after dislocation, intensive quadriceps training (isometric and isotonic exercises)

- Lysholm after 6 weeks, with a mean of 58 for the tape group and 26 for the plaster group (p = 0.001)

- After 12 weeks and 5 years, also favourable to tape (p = 0.02 and p = 0.008)

- No cases of recurrence

- Tape muscle hypotrophy was significantly lower (5.7 vs. 2.1 cm, P < 0.001)

Honkonen et al. [42]

Finland

To compare a patellar stabilizing and movement-restricting brace versus a non-articulated neoprene brace for the treatment of a first traumatic patellar dislocation

- 64 patients

- Group A (n = 32) (patellar stabilizer brace and articulated for 0°–30° ROM only)

- Group B (n = 32) (neoprene brace (no ROM restriction)

- Numbers of shifts

- Pain (VAS)

- ROM of the knee

- Tegner Activity Scale

- Score of Kujala

- Muscular trophism of the quadriceps

- Follow-up: 4 weeks, 3 months, 6 months, 12 months, 24 months and 36 months after the initial trauma

- Braces were used according to groups and both groups were advised: use of crutches for as long as necessary with full load as tolerated. All patients received similar physiotherapeutic instructions (exercise to strengthen the quadriceps muscles and lower limbs in closed kinetic chain)

- Kujala: Group A < B at 6 months (89.0 vs 93.6, [95% CI 1.07–8.14]; p = 0.01)

- Tegner: No differences

- Group A was 34.4% (11/32). Group B, rate of 37.5% (12/32) (RD, − 3.1% [95% CI 26.6–20.3%]; p = 0.8)

- Group A: 20/32 cases (62.5%) and B: 19/32 (59.4%) reported subjective joint instability symptoms

- ROM: Group A < B at 4 weeks (90° vs 115°; p < 0.001), at 3 months (125° vs 133°; p = 0.03), at 6 months (p > 0.05)

- Hypotrophy: Group A > B at 4 weeks and 3 months (24/32 vs 16/32, p = 0.5)

- VAS: No differences

Camanho et al. [38]

Brazil

To compare surgical (MPFL-R and femoral insertion) and conservative treatment for acute patellar dislocations

- 33 patients (acute patellar dislocation)

- Conservative (n = 16)

- Surgical (n = 17)

- Numbers of recurring shifts

- Role: Kujala

- Average follow-up of 40.4 months

- Conservative: immobilization (3 weeks)

- Rehabilitation started after this period with exercises to strengthen the lower limbs (emphasis on VMO), stretching for the hamstrings and the articular retinaculum were only performed 1 month after the trauma or surgery. The treatment time varied between 2 and 4 months (without pain)

- Kujala: Conservative (average 69 points), surgical (average 90–92. 22% improvement)

- Dislocations: Conservative 8/16; Surgical no case reported

- N/a

Petri et al. [20]

Germany

To compare conservative and surgical “repair the tear” treatment in patients after first patellar dislocation

- 20 patients (acute patellar dislocation)

- Conservative (n = 8)

- Surgical (n = 12)

- Patellar instability severity score

- Numbers of recurring shifts

- Role: Kujala

- Follow-up at 6, 12 and 24 months

- Conservative and surgical were treated with a ROM brace 0°–0°–60° + partial load 15 kg crutches (first 3 weeks) and 0°–0°–90° (3–6 weeks)

- Progression to full pain-adapted therapy

- Kujala: Conservative vs operative—78.6 vs 80.3 after 6 months (p = 0.8), 79.9 vs 88.9 after 12 months (p = 0.2) and 81.3 vs 87.5 after 24 months (p = 0.3)

- Conservative: 37.5% (3/8) had been dislocated

- Surgical: 16.7% (2/12) suffered dislocation within 24 months

- p = 0.5

- N/a

Bitar et al. [39]

Brazil

To compare the results of surgical (MPFL-R) versus non-surgical treatment in the treatment of primary patellar dislocation

- 36 patients (acute patellar dislocation)

- Conservative (n = 18)

- Surgical (n = 18)

- Numbers of recurring shifts

- Role: Kujala

- Minimum follow-up of 24 months

- Use of extension brace for 3 weeks and physical therapy focusing on ROM and quadriceps strengthening. Isometric quadriceps exercises, analgesia, cryotherapy, and electrical stimulation. Weight bearing after 3 weeks. Afterward, exercises were increased to gain ROM and the ergometric bicycle without load was introduced. Initial proprioception and closed kinetic chain exercises were performed and gradually evolved. Target time of 16–24 weeks

- Kujala: Conservative (70.8) < compared with Surgical group (88.9; p = 0.001).—Surgery had a higher percentage of ''good/excellent results'' (71.43%) in the Kujala, compared with the conservative group (25.0%; p = 0.003)

The conservative group had > number of recurrences and subluxations (7 patients; 35% of cases), whereas there were no reports of recurrences or subluxations in the surgical group

- N/a